This page has only limited features, please log in for full access.

Unclaimed
Y.J. Ge
College of Aerospace EngineeringNanjing University of Aeronautics and Astronautics Nanjing China

Basic Info

Basic Info is private.

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

The user biography is not available.
Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Research article
Published: 19 April 2020 in The Structural Design of Tall and Special Buildings
Reads 0
Downloads 0

Dynamic amplification effects caused by tower‐group interference is the most critical causes of wind‐induced destructions of super‐large cooling tower (SLCT), and four‐tower combinations are the most common tower‐group combining form. However, the dynamic amplification effects of SLCT of different four‐tower arrangements have not been studied systematically so far. The highest (220 m) SLCT in the world was taken as the target to conduct SLCT wind pressure measurement under 320 wind tunnel test conditions. Firstly, the stability performance under the design wind loads was analyzed. Then, the dynamic time‐history analysis was carried out, and the distribution characteristics of peak factors and values of extreme response were discussed. Furthermore, with a new concept parameter “tower‐group wind vibration coefficient” for the wind‐resistance design of SLCT, the distribution laws of two‐dimensional (2D), one‐dimensional (1D), and global tower‐group wind vibration coefficient were revealed under different four‐tower interferences. On these bases, we recommend the design parameters for wind‐resistance study of SLCT and the priority of four‐tower combination forms. The study showed that the dynamic effects of SLCT under different four‐tower arrangements were significantly different from each other and the tower‐group wind vibration coefficients proposed in this paper can reflect the interference effects of tower‐group more efficient than traditional design method. The results may become a useful database for the wind‐resistance design of SLCT and provide clues for the optimization of four‐tower arrangements in power plants.

ACS Style

Hao Wang; Shitang Ke; Tongguang Wang; Yaojun Ge; Rongkuan Zhu. Comparison of wind‐induced dynamic property of super‐large cooling tower considering different four‐tower interferences. The Structural Design of Tall and Special Buildings 2020, 29, 1 .

AMA Style

Hao Wang, Shitang Ke, Tongguang Wang, Yaojun Ge, Rongkuan Zhu. Comparison of wind‐induced dynamic property of super‐large cooling tower considering different four‐tower interferences. The Structural Design of Tall and Special Buildings. 2020; 29 (11):1.

Chicago/Turabian Style

Hao Wang; Shitang Ke; Tongguang Wang; Yaojun Ge; Rongkuan Zhu. 2020. "Comparison of wind‐induced dynamic property of super‐large cooling tower considering different four‐tower interferences." The Structural Design of Tall and Special Buildings 29, no. 11: 1.

Journal article
Published: 12 February 2020 in Renewable Energy
Reads 0
Downloads 0

The typhoon-induced vibration characteristics of large wind turbines are significantly different in different travelling stages of typhoons due to the structural complexity of typhoons. Influences of multi-stage typhoon-induced effects on structural safety of wind turbines have not been studied yet. The objective of this paper is to investigate the vibration characteristics of wind turbines in different stages of the typhoon as well as the influencing rules of the structural design standards. For this purpose, a framework was established for predicting multi-stage typhoon-induced effects of large wind turbines, which includes a new typhoon-induced multi-stage wind field simulation method and an advanced multi-body model for large wind turbines. On this basis, aerodynamic loads and dynamic response of large wind turbines during different travelling stages of typhoon were analyzed systematically based on the blade element momentum, multi-body dynamic methods, spectral analysis and data statistics. The working mechanisms of multi-stage effects on vibration characteristics of the large wind turbine were revealed. Finally, an evaluation method of vibration amplification effects for large wind turbines with considerations to multi-stage effects was established. Research results demonstrate that the proposed method can predict vibration characteristics of large wind turbines considering the multi-stage effects efficiently. The multi-stage typhoon-induced effects can influence the value of peak factor and the extremum of wind-induced force and vibration responses of large wind turbines significantly. Conversely, the wind vibration coefficient of structural design was affected slightly. Instead of using a uniform structural design standard for large wind turbines, the influence rule of multi-stage effects on anti-typhoon safety performance was summarized in this paper.

ACS Style

H. Wang; S.T. Ke; T.G. Wang; Songye Zhu. Typhoon-induced vibration response and the working mechanism of large wind turbine considering multi-stage effects. Renewable Energy 2020, 153, 740 -758.

AMA Style

H. Wang, S.T. Ke, T.G. Wang, Songye Zhu. Typhoon-induced vibration response and the working mechanism of large wind turbine considering multi-stage effects. Renewable Energy. 2020; 153 ():740-758.

Chicago/Turabian Style

H. Wang; S.T. Ke; T.G. Wang; Songye Zhu. 2020. "Typhoon-induced vibration response and the working mechanism of large wind turbine considering multi-stage effects." Renewable Energy 153, no. : 740-758.

Journal article
Published: 01 November 2019 in Journal of Aerospace Engineering
Reads 0
Downloads 0
ACS Style

Shitang Ke; Rongkuan Zhu. Typhoon-Induced Wind Pressure Characteristics on Large Terminal Roof Based on Mesoscale and Microscale Coupling. Journal of Aerospace Engineering 2019, 32, 04019093 .

AMA Style

Shitang Ke, Rongkuan Zhu. Typhoon-Induced Wind Pressure Characteristics on Large Terminal Roof Based on Mesoscale and Microscale Coupling. Journal of Aerospace Engineering. 2019; 32 (6):04019093.

Chicago/Turabian Style

Shitang Ke; Rongkuan Zhu. 2019. "Typhoon-Induced Wind Pressure Characteristics on Large Terminal Roof Based on Mesoscale and Microscale Coupling." Journal of Aerospace Engineering 32, no. 6: 04019093.

Journal article
Published: 09 October 2019 in Applied Sciences
Reads 0
Downloads 0

Wind-induced damage during the construction process and the evolution of damage over time are important reasons for the wind-induced destruction of large cooling towers. In fact, wind vibration coefficient and stability performance will evolve with the construction height and material properties over time. However, the existing studies generally ignore the impact of wind load and structural performance during the construction period. In this study, we built the 3D physical model separately for all eight construction stages a super large cooling tower which is being currently constructed and stands 210 m. The dynamic characteristics of the cooling tower were analyzed in each stage. First, the flow field information and 3D time history of aerodynamic forces were obtained for the whole construction process using large eddy simulation (LES). Full transient dynamic finite element analysis was used to calculate the dynamic responses of the tower under the real-time changes of wind loads during the whole construction process. Five calculation methods were used to trace the evolution of wind vibration coefficient during the whole construction process of the super large cooling tower. Then the formula for wind vibration coefficient changing with the construction height was fitted. The differential values of wind vibration coefficient during the whole construction process of the cooling tower were discussed by taking the meridional axial force as the objective function. On this basis, the influence and working mechanism of wind vibration coefficient, concrete age, construction load, geometric nonlinearity, internal suction force on buckling stability, and ultimate bearing capacity of the cooling towers were investigated. This research provides an enhanced understanding on the evolution of wind-induced stability performance in super large cooling towers and a methodology to prevent wind-induced damage during the construction process.

ACS Style

Shitang Ke; Peng Zhu; Lu Xu; Yaojun Ge. Evolution Mechanism of Wind Vibration Coefficient and Stability Performance during the Whole Construction Process for Super Large Cooling Towers. Applied Sciences 2019, 9, 4202 .

AMA Style

Shitang Ke, Peng Zhu, Lu Xu, Yaojun Ge. Evolution Mechanism of Wind Vibration Coefficient and Stability Performance during the Whole Construction Process for Super Large Cooling Towers. Applied Sciences. 2019; 9 (20):4202.

Chicago/Turabian Style

Shitang Ke; Peng Zhu; Lu Xu; Yaojun Ge. 2019. "Evolution Mechanism of Wind Vibration Coefficient and Stability Performance during the Whole Construction Process for Super Large Cooling Towers." Applied Sciences 9, no. 20: 4202.

Journal article
Published: 27 September 2019 in Energies
Reads 0
Downloads 0

The theoretical system of existing civil engineering typhoon models is too simplified and the simulation accuracy is very low. Therefore, in this work a meso-scale weather forecast model (WRF) based on the non-static Euler equation model was introduced to simulate typhoon “Nuri” with high spatial and temporal resolution, focusing on the comparison of wind direction and wind intensity characteristics before, during and after the landing of the typhoon. Moreover, the effectiveness of the meso-scale typhoon “Nuri” simulation was verified by a comparison between the track of the typhoon center based on minimum sea level pressure and the measured track. In this paper, the aerodynamic performance of large wind turbines under typhoon loads is studied using WRF and CFD nesting technology. A 5 MW wind turbine located in a wind power plant on the southeast coast of China has been chosen as the research object. The average and fluctuating wind pressure distributions as well as airflow around the tower body and eddy distribution on blade and tower surface were compared. A dynamic and time-historical analysis of wind-induced responses under different stop positions was implemented by considering the finite element complete transient method. The influence of the stop position on the wind-induced responses and wind fluttering factor of the system were analyzed. Finally, under a typhoon process, the most unfavorable stop position of the large wind turbine was concluded. The results demonstrated that the internal force and wind fluttering factor of the tower body increased significantly under the typhoon effect. The wind-induced response of the blade closest to the tower body was affected mostly. The wind fluttering factor of this blade was increased by 35%. It was concluded from the analysis that the large wind turbine was stopped during the typhoon. The most unfavorable stop position was at the complete overlapping of the lower blade and the tower body (Condition 1). The safety redundancy reached the maximum when the upper blade overlapped with the tower body completely (Condition 5). Therefore, it is suggested that during typhoons the blade of the wind turbine be rotated to Condition 5.

ACS Style

Shitang Ke; Lu Xu; Tongguang Wang. Aerodynamic Performance and Wind-Induced Responses of Large Wind Turbine Systems with Meso-Scale Typhoon Effects. Energies 2019, 12, 3696 .

AMA Style

Shitang Ke, Lu Xu, Tongguang Wang. Aerodynamic Performance and Wind-Induced Responses of Large Wind Turbine Systems with Meso-Scale Typhoon Effects. Energies. 2019; 12 (19):3696.

Chicago/Turabian Style

Shitang Ke; Lu Xu; Tongguang Wang. 2019. "Aerodynamic Performance and Wind-Induced Responses of Large Wind Turbine Systems with Meso-Scale Typhoon Effects." Energies 12, no. 19: 3696.

Journal article
Published: 25 January 2019 in Thin-Walled Structures
Reads 0
Downloads 0

Recent measurements made by our research group of a super-large cooling tower indicate that its fluctuations in wind-induced responses exhibit a degree of nonstationarity, echoing similar observations reported for other structures. This might cause errors in estimates of extreme responses and misunderstanding of wind-induced effects if nonstationarity is neglected. In this study, the wind-induced response signals of a super-large cooling tower (height 190 m) in a coastal region were measured for the first time under real Reynolds number and turbulent flow conditions. After noise reduction had been performed, nonstationarity of the signals was identified within various time intervals. The mean wind effect, pulsating wind effect, probability density distribution, dynamic amplification factor, and extreme responses of the super-large cooling tower were studied based on stationary and non-stationary models. Finally, the power spectral density (PSD) and evolutionary power spectral density (EPSD) of the wind-induced response signal were analyzed. The resonance spectral expression of wind-induced responses at resonance excitation points, which is applicable to super-large cooling towers, is summarized. The wind-induced responses presented strong nonstationarity. Non-stationary models that consider response nonstationarity are important in the authentic assessment of the extreme responses of super-large cooling towers. The extreme constant calculated by the stationary model cannot provide an adequate assurance rate and reduces the economic efficiency of extreme response estimates. The vibration energy distributions of resonance excitation points in different regions of the cooling tower were similar, but the PSD functions at quasi-static points were dramatically different from each other. The energy distribution of the resonant excitation points showed a phased trend, and the proposed resonance spectral expression considers three stages of variation in the PSD function of the responses to achieve high predictive accuracy.

ACS Style

Shitang Ke; Hao Wang; Yaojun Ge. Comparison of stationary and non-stationary wind-induced responses of a super-large cooling tower based on field measurements. Thin-Walled Structures 2019, 137, 331 -346.

AMA Style

Shitang Ke, Hao Wang, Yaojun Ge. Comparison of stationary and non-stationary wind-induced responses of a super-large cooling tower based on field measurements. Thin-Walled Structures. 2019; 137 ():331-346.

Chicago/Turabian Style

Shitang Ke; Hao Wang; Yaojun Ge. 2019. "Comparison of stationary and non-stationary wind-induced responses of a super-large cooling tower based on field measurements." Thin-Walled Structures 137, no. : 331-346.

Journal article
Published: 04 January 2019 in Renewable Energy
Reads 0
Downloads 0

Blade yaw will change aerodynamic performance of large-scale wind turbine structure, especially under rainstorm conditions. Structural responses and stability of large-scale wind turbine system during rainstorm are more complicated due to the impact force of rainstorm on the structural surface and its influences on the incoming turbulence. In this study, the 5 MW wind turbine tower-blade system which was developed by Nanjing University of Aeronautics and Astronautics (NUAA) was used as the research object. Firstly, the surrounding wind field of the 5 MW wind turbine tower-blade system under different yaw angles (0°, 5°, 10°, 20°, 30° and 45°) was simulated by the computational fluid dynamics (CFD) technology based on the wind-rain two-way coupling algorithm. Secondly, the wind-rain coupling synchronous iteration was carried out by adding the discrete phase model (DPM). Based on numerical simulation results, the influencing law of yaw angle on wind-driven rainfall, additional acting force of raindrops and rain-induced pressure coefficient was discussed. The velocity flow line, turbulence energy strength, raindrop running speed and trajectory action mechanism on the structural surface in wind-rain coupling field was disclosed. Moreover, the distribution laws and fitting formula of wind-rain equivalent pressure coefficient under different yaw angles were constructed. Finally, large-scale wind turbine tower-blade coupling model under different yaw angles was constructed by combining the finite element method. Structural responses, buckling stability and ultimate bearing capacity of the large-scale wind turbine system with considerations to different yaw angles under wind condition and wind-rain condition were discussed. Results demonstrated that yaw angle can affect aerodynamic force and comprehensive stress performance of the wind turbine system significantly. The wind-rain load enhances structural responses of the system, and decreases the overall buckling stability and ultimate bearing capacity of the wind turbine. Main conclusions not only can provide references for accurate load evaluation under extreme complex conditions, but also are conducive to deepen understandings on the action mechanism of wind-rain load.

ACS Style

Shitang Ke; Wenlin Yu; Tongguang Wang; Yaojun Ge. Aerodynamic performance and wind-induced effect of large-scale wind turbine system under yaw and wind-rain combination action. Renewable Energy 2019, 136, 235 -253.

AMA Style

Shitang Ke, Wenlin Yu, Tongguang Wang, Yaojun Ge. Aerodynamic performance and wind-induced effect of large-scale wind turbine system under yaw and wind-rain combination action. Renewable Energy. 2019; 136 ():235-253.

Chicago/Turabian Style

Shitang Ke; Wenlin Yu; Tongguang Wang; Yaojun Ge. 2019. "Aerodynamic performance and wind-induced effect of large-scale wind turbine system under yaw and wind-rain combination action." Renewable Energy 136, no. : 235-253.

Journal article
Published: 23 November 2018 in Journal of Wind Engineering and Industrial Aerodynamics
Reads 0
Downloads 0

Recent measurement results indicate that the wind-induced response of super-large cooling tower (include super-large cooling tower in wet-cooling-systems and super-large cooling tower in dry-cooling-systems) exhibit remarkable non-stationary feature. In this study, wind-induced response signals of a typical super-large cooling tower under real Reynolds number and turbulent conditions were collected based on field measurement. Meanwhile, some other super-large cooling towers were measured to verify the research in this paper. On these bases, non-stationary and non-Gaussian features of wind-induced response of super-large cooling tower were studied. And evolutionary power spectral density of wind-induced response of super-large cooling tower were analyzed. Furthermore, the resonance effect were discussed by studying proportion of resonance component in wind-induced response. Finally, the extreme response and damping ratios considering non-stationary feature of wind-induced effect were obtained in this paper. The results show that the wind-induced response of super-large cooling tower is characterized by stable frequency evolution characteristics and non-stationary evolution characteristics in intensity aspect. Some detailed research conclusions can provide references for wind resistance safety design of super-large cooling tower and disaster prevention study of similar tall thin-walled structure.

ACS Style

H. Wang; S.T. Ke; Y.J. Ge. Research on non-stationary wind-induced effects and the working mechanism of full scale super-large cooling tower based on field measurement. Journal of Wind Engineering and Industrial Aerodynamics 2018, 184, 61 -76.

AMA Style

H. Wang, S.T. Ke, Y.J. Ge. Research on non-stationary wind-induced effects and the working mechanism of full scale super-large cooling tower based on field measurement. Journal of Wind Engineering and Industrial Aerodynamics. 2018; 184 ():61-76.

Chicago/Turabian Style

H. Wang; S.T. Ke; Y.J. Ge. 2018. "Research on non-stationary wind-induced effects and the working mechanism of full scale super-large cooling tower based on field measurement." Journal of Wind Engineering and Industrial Aerodynamics 184, no. : 61-76.

Research article
Published: 09 November 2018 in Advances in Structural Engineering
Reads 0
Downloads 0

The wind loads distribution on the super-large cooling tower under the interference effect of tower group is very complicated. Particularly, energy distribution of fluctuation wind loads and extreme model is difficult to be predicted. However, accurate calculations of these two factors are the most direct ways for analysis of wind resistance dynamics of super-large cooling tower. The wind tunnel tests of the highest super-large cooling tower under five typical tower combinations (serial, rectangular, rhombus, L-shaped, and inclined L-shaped) with 320 working conditions were performed. On this basis, non-Gaussian and non-stationary properties of local wind pressure and overall force coefficient of super-large cooling tower were analyzed. Distribution laws of local wind pressure extremes and overall force coefficient extremes were discussed based on Hermite method and peak factor method. Key attention was paid to the mapping relationships of characteristic angles with local and overall aerodynamic force extremes. The effects of four-tower combination modes on fluctuation wind loads energy of super-large cooling tower were studied based on the power spectral density function, intrinsic mode function, and evolution power spectral density function. Besides, the estimation formulas of local wind pressure spectrum and overall pressure coefficient spectrum of super-large cooling tower under four-tower combination were proposed. It can be found that the extremes of local wind pressure and overall aerodynamic force could be predicted based on the linear relationship between characteristic angles and fluctuation wind loads. In addition, it is suggested to choose serial combination first, followed by inclined L-shaped, L-shaped, rhombus, and rectangular modes successively.

ACS Style

Hao Wang; Shitang Ke; Yaojun Ge; Yukio Tamura. Extreme and spectrum characteristics of wind loads on super-large cooling tower under different four-tower combinations. Advances in Structural Engineering 2018, 22, 1238 -1250.

AMA Style

Hao Wang, Shitang Ke, Yaojun Ge, Yukio Tamura. Extreme and spectrum characteristics of wind loads on super-large cooling tower under different four-tower combinations. Advances in Structural Engineering. 2018; 22 (5):1238-1250.

Chicago/Turabian Style

Hao Wang; Shitang Ke; Yaojun Ge; Yukio Tamura. 2018. "Extreme and spectrum characteristics of wind loads on super-large cooling tower under different four-tower combinations." Advances in Structural Engineering 22, no. 5: 1238-1250.

Journal article
Published: 19 October 2018 in Applied Sciences
Reads 0
Downloads 0

Compared with normal wind, typhoons may change the flow field surrounding wind turbines, thus influencing their wind-induced responses and stability. The existing typhoon theoretical model in the civil engineering field is too simplified. To address this problem, the WRF (Weather Research Forecasting) model was introduced for high-resolution simulation of the Typhoon “Nuri” firstly. Secondly, the typhoon field was analyzed, and the wind speed profile of the boundary layer was fitted. Meanwhile, the normal wind speed profile with the same wind speed of the typhoon speed profile at the gradient height of class B landform in the code was set. These two wind speed profiles were integrated into the UDF (User Defined Function). On this basis, a five-MW wind turbine in Shenzhen was chosen as the research object. The action mechanism of speed was streamlined and turbulence energy surrounding the wind turbine was disclosed by microscale CFD (Computational Fluid Dynamics) simulation. The influencing laws of a typhoon and normal wind on wind pressure distribution were compared. Finally, key attention was paid to analyzing the structural response, buckling stability, and ultimate bearing capacity of the wind turbine system. The research results demonstrated that typhoons increased the aerodynamic force and structural responses, and decreased the overall buckling stability and ultimate bearing capacity of the wind turbine.

ACS Style

Shitang Ke; Wenlin Yu; Jiufa Cao; Tongguang Wang. Aerodynamic Force and Comprehensive Mechanical Performance of a Large Wind Turbine during a Typhoon Based on WRF/CFD Nesting. Applied Sciences 2018, 8, 1982 .

AMA Style

Shitang Ke, Wenlin Yu, Jiufa Cao, Tongguang Wang. Aerodynamic Force and Comprehensive Mechanical Performance of a Large Wind Turbine during a Typhoon Based on WRF/CFD Nesting. Applied Sciences. 2018; 8 (10):1982.

Chicago/Turabian Style

Shitang Ke; Wenlin Yu; Jiufa Cao; Tongguang Wang. 2018. "Aerodynamic Force and Comprehensive Mechanical Performance of a Large Wind Turbine during a Typhoon Based on WRF/CFD Nesting." Applied Sciences 8, no. 10: 1982.

Journal article
Published: 01 August 2018 in Journal of Wind Engineering and Industrial Aerodynamics
Reads 0
Downloads 0
ACS Style

Shitang Ke; Hao Wang; Tongguang Wang; Yaojun Ge. Comparison of comprehensive stress performances of super-large cooling tower in different four-tower arrangements under 3D asymmetric wind loads. Journal of Wind Engineering and Industrial Aerodynamics 2018, 179, 158 -172.

AMA Style

Shitang Ke, Hao Wang, Tongguang Wang, Yaojun Ge. Comparison of comprehensive stress performances of super-large cooling tower in different four-tower arrangements under 3D asymmetric wind loads. Journal of Wind Engineering and Industrial Aerodynamics. 2018; 179 ():158-172.

Chicago/Turabian Style

Shitang Ke; Hao Wang; Tongguang Wang; Yaojun Ge. 2018. "Comparison of comprehensive stress performances of super-large cooling tower in different four-tower arrangements under 3D asymmetric wind loads." Journal of Wind Engineering and Industrial Aerodynamics 179, no. : 158-172.

Research article
Published: 08 July 2018 in Mathematical Problems in Engineering
Reads 0
Downloads 0

By focusing on wind-rain two-way coupling algorithm, simulation iterations of wind field and raindrops in the world highest cooling tower (210m) in northwest China were carried out using continuous phase and discrete phase models based on CFD numerical simulation. Firstly, influence laws of 9 wind velocity-rainfall intensity combinations on wind-induced rainfall, raindrop additional force, and equivalent pressure coefficient on internal and external surface of the tower body were discussed. On this basis, speed flow line, turbulence energy strength, raindrop running speed, and track on the tower body in the wind-rain coupling field were disclosed. Finally, qualitative and quantitative contrastive analyses on wind pressure, rain pressure, and equivalent pressure coefficient on internal and external surfaces of the tower body were conducted under different working conditions. Thus, the most unfavorable wind-rain combination was identified. Calculation formulas of equivalent internal and external pressure coefficients of super-large cooling towers were fitted from nonlinear least square method. Research results demonstrate that the 3D effect of equivalent internal and external pressure coefficients with considerations to wind-rain two-way coupling is more prominent. Particularly, there is strong transition on the windward region of the external surface and leeside region at bottom of internal surface. The quantity of caught raindrops on the structural surface is negatively related to wind velocity but is positively related to rainfall intensity. Rain load and rainfall coefficients on the external surface are significantly higher than those on the internal surface. Equivalent internal pressure coefficient has a sharp reduction on the leeside region under different working conditions. Besides, equivalent internal pressure coefficient of different meridians decreases with the increase of height. The maximum and minimum are -0.574 and -0.282, respectively. The proposed equivalent internal and external pressure coefficients of super-large cooling tower can predict wind load under extreme climate conditions accurately.

ACS Style

Shitang Ke; Wenlin Yu; Yaojun Ge. Wind Load Characteristics and Action Mechanism on Internal and External Surfaces of Super-Large Cooling Towers under Wind-Rain Combined Effects. Mathematical Problems in Engineering 2018, 2018, 1 -22.

AMA Style

Shitang Ke, Wenlin Yu, Yaojun Ge. Wind Load Characteristics and Action Mechanism on Internal and External Surfaces of Super-Large Cooling Towers under Wind-Rain Combined Effects. Mathematical Problems in Engineering. 2018; 2018 ():1-22.

Chicago/Turabian Style

Shitang Ke; Wenlin Yu; Yaojun Ge. 2018. "Wind Load Characteristics and Action Mechanism on Internal and External Surfaces of Super-Large Cooling Towers under Wind-Rain Combined Effects." Mathematical Problems in Engineering 2018, no. : 1-22.

Research article
Published: 02 July 2018 in The Structural Design of Tall and Special Buildings
Reads 0
Downloads 0

A cylindrical–conical steel cooling tower (SCT) is a new type of very large thin‐walled, flexible structure. This study focused on the wind loads on the internal and outer surfaces of this structure and its wind‐induced responses. First, using the computational fluid dynamics method, the numerical wind tunnel was conducted to simulate a 189‐m‐high cylindrical–conical SCT, Asia's highest cooling tower that is still under construction. This numerical method was validated by comparing the wind pressures across typical cross sections of the tower model's cylindrical and conical segments with known standard curves. Based on this, the features of the airflow around the typical cross sections and its wake were extracted, and the distribution of mean wind loads along the internal and outer surfaces of the cylindrical and conical sections was obtained. Then functions for estimating the internal and outer surfaces shape factors of the cylindrical and conical segments were obtained by fitting to the simulated data. Furthermore, finite element method was used to analyze the static wind‐induced response of the cylindrical–conical SCT under internal pressure, external pressure, or both internal and external pressure. The effect patterns of internal pressures on the wind‐induced responses of the main tube, stiffening trusses, and auxiliary trusses of the tower were derived from the analysis results. Main findings of the research can provide a reference for design of very large cylindrical–conical SCTs for wind resistance in the future.

ACS Style

Shitang Ke; Lingyun Du; Yaojun Ge. Wind-induced internal pressure effect within a novel super-large cylindrical-conical steel cooling tower. The Structural Design of Tall and Special Buildings 2018, 27, e1510 .

AMA Style

Shitang Ke, Lingyun Du, Yaojun Ge. Wind-induced internal pressure effect within a novel super-large cylindrical-conical steel cooling tower. The Structural Design of Tall and Special Buildings. 2018; 27 (15):e1510.

Chicago/Turabian Style

Shitang Ke; Lingyun Du; Yaojun Ge. 2018. "Wind-induced internal pressure effect within a novel super-large cylindrical-conical steel cooling tower." The Structural Design of Tall and Special Buildings 27, no. 15: e1510.

Journal article
Published: 01 June 2018 in Thin-Walled Structures
Reads 0
Downloads 0

The natural frequency is a key factor for estimation of dynamic deformation and mechanical performance. As simple and effective estimation equation for natural frequency of cooling tower is absent, current investigations of natural frequency of cooling towers are basically based on finite element analyses. In this study, 38 models of a 179 m cooling tower were established by tuning key structural parameters (e.g., tower height, throat height, throat diameter, inlet height, and pillar sectional area) and dynamic characteristics of these models were analyzed. Also, effects of structural parameters on fundamental frequency and overturning frequency were investigated. The sensitivity analysis of structural natural frequency for cooling towers was executed using the perturbation method and the Latin hypercube sampling method and sensitivity factors of different parameters corresponding to different orders were obtained. Based on that, multi-parameter empirical estimation equations for fundamental frequency and overturning frequency considering weighted sensitivity factor were proposed. Then, the estimation equation of natural frequency is verified by field tests of eight cooling towers with typical tower heights and configurations. Specifically, the measured acceleration signals were pre-treated using random decrement method (RDT) and natural excitation technique (NExT) and the first 10 order natural frequencies of the cooling tower using three time-domain modal identification methods (ARMA, ITD, and STD). Finally, structural parameters of cooling tower obtained by field tests were fitted. The results indicated that the fundamental frequency of cooling towers decreases as tower height and throat height increase and increases as throat diameter, inlet height, and pillar sectional area increase. Although sensitivity factors obtained by the two methods are similar, the LHS method shows higher accuracy. The effect of tower height on natural frequency is most significant among all parameters, which means the sensitivity factor of tower height is higher than those of other parameters. The measured fundamental frequencies of cooling towers were between 0.6 Hz and 1.9 Hz and heights and configurations of cooling towers have significant effects on their dynamic characteristics. The field test results of eight cooling towers demonstrated reasonable effectiveness of the proposed empirical estimation equations for the fundamental frequency and overturning frequency of cooling towers (the maximum goodness of fit of fundamental frequency and overturning frequency were 0.996 and 0.975, respectively). Error analysis indicated that the proposed estimation equation for natural frequency is highly accurate and reliable. This study provides references for determination of structural natural frequency of large cooling towers and future studies on structural natural vibration characteristics.

ACS Style

Shitang Ke; Lu Xu; Yaojun Ge. Sensitivity analysis and estimation method of natural frequency for large cooling tower based on field measurement. Thin-Walled Structures 2018, 127, 809 -821.

AMA Style

Shitang Ke, Lu Xu, Yaojun Ge. Sensitivity analysis and estimation method of natural frequency for large cooling tower based on field measurement. Thin-Walled Structures. 2018; 127 ():809-821.

Chicago/Turabian Style

Shitang Ke; Lu Xu; Yaojun Ge. 2018. "Sensitivity analysis and estimation method of natural frequency for large cooling tower based on field measurement." Thin-Walled Structures 127, no. : 809-821.

Journal article
Published: 15 May 2018 in Energies
Reads 0
Downloads 0

Convergence performance and optimization efficiency are two critical issues in the application of commonly used evolution algorithms in multi-objective design of wind turbines. A gradient-based multi-objective evolution algorithm is proposed for wind turbine blade design, based on uniform decomposition and positive-gradient differential evolution. In the uniform decomposition, uniformly distributed reference vectors are established in the objective space to maintain population diversity so that the population aggregations, which are commonly observed for wind turbine blade design using gradient-free algorithms, are minimized. The positive-gradient differential evolution is introduced for population evolution to increase optimization efficiency by guiding the evolutionary process and significantly reducing searching ranges of each individual. Two-, three- and four-objective optimizations of 1.5 MW wind turbine blades reveal that the proposed algorithm can deliver uniformly distributed optimal solutions in an efficient way, and has advantages over gradient-free algorithms in terms of convergence performance and optimization efficiency. These advantages increase with the optimization dimension, and the proposed algorithm is more suitable for optimizations of small size populations, thus remarkably enhancing the design efficiency.

ACS Style

Long Wang; Ran Han; Tongguang Wang; Shitang Ke. Uniform Decomposition and Positive-Gradient Differential Evolution for Multi-Objective Design of Wind Turbine Blade. Energies 2018, 11, 1262 .

AMA Style

Long Wang, Ran Han, Tongguang Wang, Shitang Ke. Uniform Decomposition and Positive-Gradient Differential Evolution for Multi-Objective Design of Wind Turbine Blade. Energies. 2018; 11 (5):1262.

Chicago/Turabian Style

Long Wang; Ran Han; Tongguang Wang; Shitang Ke. 2018. "Uniform Decomposition and Positive-Gradient Differential Evolution for Multi-Objective Design of Wind Turbine Blade." Energies 11, no. 5: 1262.

Research article
Published: 11 May 2018 in The Structural Design of Tall and Special Buildings
Reads 0
Downloads 0

Standard 5% damping ratio for high‐rise concrete structures is generally used for dynamic analysis under the action of wind and earthquakes in the existing cooling tower regulations and researches. But considering the unique configuration and material attributes of large cooling towers, the actual damping ratio must be far smaller than the recommended. However, only a few field measurements of damping ratio for large cooling towers have been conducted; neither are there thorough investigation into the qualitative and quantification of wind and seismic effects under different damping ratio. To fill this gap, field measurements of a large cooling tower standing 179 m in northwestern China was performed and acceleration vibration signals at representative positions of the tower under ambient excitation were obtained. The vibration signals were preprocessed combining random decrement technique and natural excitation technique. Three pattern recognition methods (auto‐regressive and moving mean model, Ibrahim time domain, and spare time domain (STD)) were applied to analyze the frequencies, damping ratios, and modes of vibration for the first 10 order modes. Following the line of thought of modal combination, the equivalent synthetic damping ratio was derived. Under 5 damping ratios (0.5%, 1%, 2%, 3%, and 5%), a comparative analysis on the dynamic responses of the cooling tower to wind and single seismic loading by using full transient method was performed. On this basis, the patterns of influence of damping ratio on wind‐induced vibration, wind vibration coefficient, and time history and extrema of seismic responses were extracted. Finally, different combinations of dead weight, wind, temperature in winter, sunshine duration, and seismic intensity and those of accidental seismic effects (8 working conditions) were considered, using equivalent synthetic damping ratio and standard damping ratio. Thus, the most unfavorable working conditions were identified under actual and standard damping ratios for the large cooling tower. Our research findings provide reference for determining the value of damping ratio in large cooling towers and deepening the understanding on the influence mechanism of damping ratio.

ACS Style

S.T. Ke; W. Yu; L. Xu; Y.J. Ge; Y. Tamura. Identification of damping ratio and its influences on wind- and earthquake-induced effects for large cooling towers. The Structural Design of Tall and Special Buildings 2018, 27, e1488 .

AMA Style

S.T. Ke, W. Yu, L. Xu, Y.J. Ge, Y. Tamura. Identification of damping ratio and its influences on wind- and earthquake-induced effects for large cooling towers. The Structural Design of Tall and Special Buildings. 2018; 27 (12):e1488.

Chicago/Turabian Style

S.T. Ke; W. Yu; L. Xu; Y.J. Ge; Y. Tamura. 2018. "Identification of damping ratio and its influences on wind- and earthquake-induced effects for large cooling towers." The Structural Design of Tall and Special Buildings 27, no. 12: e1488.

Journal article
Published: 10 May 2018 in Modern Physics Letters B
Reads 0
Downloads 0

The current work describes a novel technique for wind turbine rotor optimization. The aerodynamic design and optimization of wind turbine rotor can be achieved with different methods, such as the semi-empirical engineering methods and more accurate computational fluid dynamic (CFD) method. The CFD method often provides more detailed aerodynamics features during the design process. However, high computational cost limits the application, especially for rotor optimization purpose. In this paper, a CFD-based actuator disc (AD) model is used to represent turbulent flow over a wind turbine rotor. The rotor is modeled as a permeable disc of equivalent area where the forces from the blades are distributed on the circular disc. The AD model is coupled with a Reynolds Averaged Navier–Stokes (RANS) solver such that the thrust and power are simulated. The design variables are the shape parameters comprising the chord, the twist and the relative thickness of the wind turbine rotor blade. The comparative aerodynamic performance is analyzed between the original and optimized reference wind turbine rotor. The results showed that the optimization framework can be effectively and accurately utilized in enhancing the aerodynamic performance of the wind turbine rotor.

ACS Style

Jiufa Cao; Wei Jun Zhu; Tongguang Wang; Shitang Ke. Aerodynamic optimization of wind turbine rotor using CFD/AD method. Modern Physics Letters B 2018, 32, 1 .

AMA Style

Jiufa Cao, Wei Jun Zhu, Tongguang Wang, Shitang Ke. Aerodynamic optimization of wind turbine rotor using CFD/AD method. Modern Physics Letters B. 2018; 32 (12n13):1.

Chicago/Turabian Style

Jiufa Cao; Wei Jun Zhu; Tongguang Wang; Shitang Ke. 2018. "Aerodynamic optimization of wind turbine rotor using CFD/AD method." Modern Physics Letters B 32, no. 12n13: 1.

Article
Published: 17 January 2018 in The Structural Design of Tall and Special Buildings
Reads 0
Downloads 0

An efficient approach for predicting wind-induced fatigue in large horizontal axis wind turbine coupled tower–blade structures subject to aeroelastic and yaw effects is presented. First, aerodynamic loads under yaw conditions are simulated based on the harmonic superposition method and modified blade element momentum theory, in which wind shear, tower shadow, tower–blade interactions, aeroelastic, and rotational effects are taken into account. Then, a nonlinear time-history of wind-induced responses under simulated aerodynamic loads is obtained. Finally, based on these results, wind-induced fatigue damage and lifespan are predicted according to linear cumulative damage theory. For completeness, the influences of mean wind speed, aeroelasticity, and yaw angle on horizontal axis wind turbine fatigue life are discussed. The results indicate that the aerodynamic loads and residual fatigue life can be estimated accurately by the proposed model, which can be used to simulate the 3D wind fields of wind turbines under given wind conditions. The wind energy of the wind turbine blade is mainly concentrated at its edge and is weaker at the hub. Estimation of wind turbine fatigue life is therefore suggested to be based on the component with the shortest life, being the blade root. Furthermore, yaw conditions significantly shorten fatigue life and should not be ignored. Fatigue life is also rather sensitive to mean wind speed.

ACS Style

Shitang Ke; Tongguang Wang; Yaojun Ge; Hao Wang. Wind-induced fatigue of large HAWT coupled tower-blade structures considering aeroelastic and yaw effects. The Structural Design of Tall and Special Buildings 2018, 27, e1467 .

AMA Style

Shitang Ke, Tongguang Wang, Yaojun Ge, Hao Wang. Wind-induced fatigue of large HAWT coupled tower-blade structures considering aeroelastic and yaw effects. The Structural Design of Tall and Special Buildings. 2018; 27 (9):e1467.

Chicago/Turabian Style

Shitang Ke; Tongguang Wang; Yaojun Ge; Hao Wang. 2018. "Wind-induced fatigue of large HAWT coupled tower-blade structures considering aeroelastic and yaw effects." The Structural Design of Tall and Special Buildings 27, no. 9: e1467.

Journal article
Published: 01 November 2017 in Journal of Wind Engineering and Industrial Aerodynamics
Reads 0
Downloads 0
ACS Style

Shitang Ke; Hao Wang; Yaojun Ge. Interference effect and the working mechanism of wind loads in super-large cooling towers under typical four-tower arrangements. Journal of Wind Engineering and Industrial Aerodynamics 2017, 170, 197 -213.

AMA Style

Shitang Ke, Hao Wang, Yaojun Ge. Interference effect and the working mechanism of wind loads in super-large cooling towers under typical four-tower arrangements. Journal of Wind Engineering and Industrial Aerodynamics. 2017; 170 ():197-213.

Chicago/Turabian Style

Shitang Ke; Hao Wang; Yaojun Ge. 2017. "Interference effect and the working mechanism of wind loads in super-large cooling towers under typical four-tower arrangements." Journal of Wind Engineering and Industrial Aerodynamics 170, no. : 197-213.

Article
Published: 25 July 2017 in The Structural Design of Tall and Special Buildings
Reads 0
Downloads 0

Large cylindrical–conical steel cooling tower (SCT) represents a new configuration of cooling tower, and its wind load distribution pattern and forming mechanism are very different from those of the traditional hyperbolic cooling towers. Large eddy simulation was used for the numerical simulation on a superlarge cylindrical–conical SCT that exceeds the specification limit, which is also the highest (189 m) SCT under construction in Asia. The surface flow field and time history of 3-D aerodynamic force were obtained for the cylindrical and conical parts, respectively. Comparison with the measurements of other large cooling towers and the results of wind tunnel test confirmed the validity of the numerical simulation. Then, based on the probability density distribution and spatial correlation of representative measuring points, regions of non-Gaussian distribution were identified. The forming mechanism of non-Gaussian wind pressure distribution was revealed from the perspective of the correlation of non-Gaussian distribution versus flow separation and eddy motion. The criteria for classifying the region of non-Gaussian distribution for the cylindrical and conical parts were analyzed, respectively. Research shows that the wind pressures in the windward regions of conical and cylindrical parts obey Gaussian distribution; however, the wind pressures from the region of extreme negative pressure to the region of flow separation are largely non-Gaussian and the wind pressures of the conical part are generally non-Gaussian in the leeward region. Finally, the three algorithms for calculating the extreme values of wind pressure were used, namely, peak factor method, improved peak factor method, and Sadek–Simiu method. The distribution patterns of peak factors and extreme values of wind pressure in SCT towers were analyzed comparatively. The 2-D formulae for fitting the extreme values of wind values for the cylindrical and conical parts were derived by nonlinear least square method. Moreover, strategy for value determination was also presented. The present research aimed to strengthen the understanding of the fluctuating wind pressure distribution and its forming mechanism for large cylindrical–conical SCT towers.

ACS Style

Shitang Ke; Hao Wang; Yaojun Ge. Non-Gaussian characteristics and extreme distribution of fluctuating wind pressures on large cylindrical-conical steel cooling towers. The Structural Design of Tall and Special Buildings 2017, 26, e1403 .

AMA Style

Shitang Ke, Hao Wang, Yaojun Ge. Non-Gaussian characteristics and extreme distribution of fluctuating wind pressures on large cylindrical-conical steel cooling towers. The Structural Design of Tall and Special Buildings. 2017; 26 (18):e1403.

Chicago/Turabian Style

Shitang Ke; Hao Wang; Yaojun Ge. 2017. "Non-Gaussian characteristics and extreme distribution of fluctuating wind pressures on large cylindrical-conical steel cooling towers." The Structural Design of Tall and Special Buildings 26, no. 18: e1403.