This page has only limited features, please log in for full access.
The release of large quantities of CO2 into the atmosphere is one of the major causes of global warming. The most viable method to control the level of CO2 in the atmosphere is to capture and permanently sequestrate the excess amount of CO2 in subsurface geological reservoirs. The injection of CO2 gives rise to pore pressure buildup. It is crucial to monitor the rising pore pressure in order to prevent the potential failure of the reservoir and the subsequent leakage of the stored CO2 into the overburden layers, and then back to the atmosphere. In this paper, the Minjur sandstone reservoir in eastern Saudi Arabia was considered for establishing a coupled geomechanical model and performing the corresponding stability analysis. During the geomechanical modeling process, the fault passing through the Minjur and Marrat layers was also considered. The injection-induced pore-pressure and ground uplift profiles were calculated for the case of absence of a fault across the reservoir, as well as the case with a fault. The stability analysis was performed using the Mohr–Coulomb failure criterion. In the current study, the excessive increase in pore pressure, in the absence of geological faults, moved the reservoir closer to the failure envelope, but in the presence of geological faults, the reservoir reached to the failure envelope and the faults were activated. The developed geomechanical model provided estimates for the safe injection parameters of CO2 based on the magnitudes of the reservoir pore pressure and stresses in the reservoir.
Sikandar Khan; Yehia Khulief; Abdullatif Al-Shuhail; Salem Bashmal; Naveed Iqbal. The Geomechanical and Fault Activation Modeling during CO2 Injection into Deep Minjur Reservoir, Eastern Saudi Arabia. Sustainability 2020, 12, 9800 .
AMA StyleSikandar Khan, Yehia Khulief, Abdullatif Al-Shuhail, Salem Bashmal, Naveed Iqbal. The Geomechanical and Fault Activation Modeling during CO2 Injection into Deep Minjur Reservoir, Eastern Saudi Arabia. Sustainability. 2020; 12 (23):9800.
Chicago/Turabian StyleSikandar Khan; Yehia Khulief; Abdullatif Al-Shuhail; Salem Bashmal; Naveed Iqbal. 2020. "The Geomechanical and Fault Activation Modeling during CO2 Injection into Deep Minjur Reservoir, Eastern Saudi Arabia." Sustainability 12, no. 23: 9800.
The excessive burning of the fossil fuels has caused severe global climatic changes such as increasing the global temperature, causing initiation of the wild fire, rising the sea level, increasing the floods, storms, amount of rain and snow. One of the effective global mitigation strategies is sequestration of huge quantity of CO2 deep below the ground level for a long period of time. An important issue is to ensure the permanency and safety of the sequestration process due to the associated pore-pressure buildup. It is necessary to have correct estimates of the pore-pressure buildup, ground uplift and re-activation of any existing fault during the process of CO2 injection and long-term storage. In this investigation, the effects of reservoir size and boundary conditions are investigated by means of geomechanical modeling of the deep Biyadh sandstone reservoir in Saudi Arabia. Currently, carbon dioxide is not injected into the actual Biyadh reservoir. In this investigative modeling, CO2 is injected for an injection period of ten years using a single injection well at the center of the reservoir. The developed modeling scheme for a single injection well has been extended further to include multiple injection wells. For multiple injection wells, the reservoir size and locations of injection wells are varied to evaluate their effect on the pore-pressure buildup and ground uplift. The reservoir stability analysis has been performed using Mohr–Coulomb failure criterion for both small and large reservoir models, with the same injection parameters. The simulation results demonstrated that pressure buildup and ground uplift are relatively higher for reservoirs with small sizes and closed boundaries; while in the case of large sizes and open boundaries, the pore-pressure buildup and ground uplift are relatively lower. Moreover, the effect of the reservoir size and boundary conditions on the reactivation of faults during CO2 injection has been evaluated. The stability analysis performed in this study shows that injecting CO2 into larger size reservoir is safer as compared to smaller size reservoir. Injecting CO2 with multiple injection wells will cause pore-pressure buildup of huge magnitudes. The modeling results show that suggesting a representative volume for the reservoir during CO2 injection can under-estimate the pore-pressure buildup and fault re-activation that can cause the reservoir failure and leakage of the stored CO2.
Sikandar Khan; Y. A. Khulief; A. A. Al-Shuhail. Effects of reservoir size and boundary conditions on pore-pressure buildup and fault reactivation during CO2 injection in deep geological reservoirs. Environmental Earth Sciences 2020, 79, 1 -23.
AMA StyleSikandar Khan, Y. A. Khulief, A. A. Al-Shuhail. Effects of reservoir size and boundary conditions on pore-pressure buildup and fault reactivation during CO2 injection in deep geological reservoirs. Environmental Earth Sciences. 2020; 79 (12):1-23.
Chicago/Turabian StyleSikandar Khan; Y. A. Khulief; A. A. Al-Shuhail. 2020. "Effects of reservoir size and boundary conditions on pore-pressure buildup and fault reactivation during CO2 injection in deep geological reservoirs." Environmental Earth Sciences 79, no. 12: 1-23.
The continuous emission of carbon dioxide to the environment has caused major climatic changes and is the main cause of the global warming. In order to mitigate the level of carbon dioxide in the atmosphere, the excess amount of carbon dioxide needs to be permanently stored in the deep sedimentary rocks. The pore pressure buildup during carbon dioxide injection process needs to be monitored in order to prevent the failure of the reservoir and hence the leakage of the stored carbon dioxide. In this paper, coupled geomechanical modeling and stability analysis are performed for the Minjur Sandstone reservoir in Saudi Arabia. The pore pressure buildup and ground uplift was calculated during carbon dioxide injection into the reservoir. The Mohr-Coulomb failure criterion was utilized to perform the stability analysis of the reservoir. The stability analysis was performed for the reservoir which suggested safe carbon dioxide injection parameters based on the changes in the pore pressure and horizontal stresses in the reservoir.
Sikandar Khan; Y. A. Khulief; A. A. Al-Shuhail. Coupled Reservoir-Geomechanical Modeling and Stability Analysis during CO 2 Injection into Minjur Sandstone Reservoir. World Environmental and Water Resources Congress 2018 2018, 1 .
AMA StyleSikandar Khan, Y. A. Khulief, A. A. Al-Shuhail. Coupled Reservoir-Geomechanical Modeling and Stability Analysis during CO 2 Injection into Minjur Sandstone Reservoir. World Environmental and Water Resources Congress 2018. 2018; ():1.
Chicago/Turabian StyleSikandar Khan; Y. A. Khulief; A. A. Al-Shuhail. 2018. "Coupled Reservoir-Geomechanical Modeling and Stability Analysis during CO 2 Injection into Minjur Sandstone Reservoir." World Environmental and Water Resources Congress 2018 , no. : 1.
Sikandar Khan; Y.A. Khulief; Abdullatif Al-Shuhail. The effect of injection well arrangement on CO2 injection into carbonate petroleum reservoir. International Journal of Global Warming 2018, 14, 462 .
AMA StyleSikandar Khan, Y.A. Khulief, Abdullatif Al-Shuhail. The effect of injection well arrangement on CO2 injection into carbonate petroleum reservoir. International Journal of Global Warming. 2018; 14 (4):462.
Chicago/Turabian StyleSikandar Khan; Y.A. Khulief; Abdullatif Al-Shuhail. 2018. "The effect of injection well arrangement on CO2 injection into carbonate petroleum reservoir." International Journal of Global Warming 14, no. 4: 462.
Sikandar Khan; Y. A. Khulief; A. A. Al-Shuhail. Numerical Modeling of the Geomechanical Behavior of Biyadh Reservoir Undergoing CO 2 Injection. International Journal of Geomechanics 2017, 17, 04017039 .
AMA StyleSikandar Khan, Y. A. Khulief, A. A. Al-Shuhail. Numerical Modeling of the Geomechanical Behavior of Biyadh Reservoir Undergoing CO 2 Injection. International Journal of Geomechanics. 2017; 17 (8):04017039.
Chicago/Turabian StyleSikandar Khan; Y. A. Khulief; A. A. Al-Shuhail. 2017. "Numerical Modeling of the Geomechanical Behavior of Biyadh Reservoir Undergoing CO 2 Injection." International Journal of Geomechanics 17, no. 8: 04017039.
Sedimentary porous rocks can be used for long-term subsurface containment of CO2. Before injecting CO2 to sedimentary reservoirs, it is necessary to perform stability analysis of the reservoir and to estimate the maximum sustainable pore fluid pressures. In order to avoid the reservoir damage during the CO2 injection, the effective stresses in the reservoir should be evaluated. In this paper, numerical modeling techniques are used for the evaluation of stresses and deformations in a naturally fractured carbonate sedimentary reservoir. The developed numerical modeling scheme couples the behavior of the CO2 injection and the change in the geomechanical behavior of the sedimentary carbonate reservoir for a case study from Saudi Arabia. The present investigation extends the previous studies by considering the sorption-based deformation during the injection of the compressed CO2 fluid into the Arab-D naturally fractured carbonate reservoir. The change in permeability during the injection of CO2 is evaluated. The adopted CO2 injection scenario was shown to be within the safe maximum occupancy, and that the increase in the pore pressure does not result in the reservoir failure.
Sikandar Khan; Abdullatif Al-Shuhail; Y. A. Khulief. Numerical modeling of the geomechanical behavior of Ghawar Arab-D carbonate petroleum reservoir undergoing CO2 injection. Environmental Earth Sciences 2016, 75, 1499 .
AMA StyleSikandar Khan, Abdullatif Al-Shuhail, Y. A. Khulief. Numerical modeling of the geomechanical behavior of Ghawar Arab-D carbonate petroleum reservoir undergoing CO2 injection. Environmental Earth Sciences. 2016; 75 (24):1499.
Chicago/Turabian StyleSikandar Khan; Abdullatif Al-Shuhail; Y. A. Khulief. 2016. "Numerical modeling of the geomechanical behavior of Ghawar Arab-D carbonate petroleum reservoir undergoing CO2 injection." Environmental Earth Sciences 75, no. 24: 1499.
Yehia A Khulief. Welcome to the Inaugural Issue of the IRATJ. International Robotics & Automation Journal 2016, 1, 1 -1.
AMA StyleYehia A Khulief. Welcome to the Inaugural Issue of the IRATJ. International Robotics & Automation Journal. 2016; 1 (1):1-1.
Chicago/Turabian StyleYehia A Khulief. 2016. "Welcome to the Inaugural Issue of the IRATJ." International Robotics & Automation Journal 1, no. 1: 1-1.
M. El-Gebeily; Y.A. Khulief. Identification of wall-thinning and cracks in pipes utilizing vibration modes and wavelets. Applied Mathematical Modelling 2016, 40, 5335 -5348.
AMA StyleM. El-Gebeily, Y.A. Khulief. Identification of wall-thinning and cracks in pipes utilizing vibration modes and wavelets. Applied Mathematical Modelling. 2016; 40 (9-10):5335-5348.
Chicago/Turabian StyleM. El-Gebeily; Y.A. Khulief. 2016. "Identification of wall-thinning and cracks in pipes utilizing vibration modes and wavelets." Applied Mathematical Modelling 40, no. 9-10: 5335-5348.
A finite element formulation using the B-spline wavelets on the interval is developed for modeling the free vibrations of composite pipes. The composite FRP pipe element is treated as a beam element. The finite pipe element is constructed in the wavelet space and then transformed to the physical space. Detailed expressions of the mass and stiffness matrices are derived for the composite pipe using the B-spline scaling and wavelet functions. Both Euler-Bernoulli and Timoshenko beam theories are considered. The generalized eigenvalue problem is formulated and solved to obtain the modal characteristics of the composite pipe. The developed wavelet-based finite element discretization scheme utilizes significantly less elements compared to the conventional finite element method for modeling composite pipes. Numerical solutions are obtained to demonstrate the accuracy of the developed element, which is verified by comparisons with some available results in the literature.
Wasiu A. Oke; Yehia A. Khulief. Vibration analysis of composite pipes using the finite element method with B-spline wavelets. Journal of Mechanical Science and Technology 2016, 30, 623 -635.
AMA StyleWasiu A. Oke, Yehia A. Khulief. Vibration analysis of composite pipes using the finite element method with B-spline wavelets. Journal of Mechanical Science and Technology. 2016; 30 (2):623-635.
Chicago/Turabian StyleWasiu A. Oke; Yehia A. Khulief. 2016. "Vibration analysis of composite pipes using the finite element method with B-spline wavelets." Journal of Mechanical Science and Technology 30, no. 2: 623-635.
Wall-thinning due to chemical reactions, heat, erosion, or a combination of such influences is the most dominant type of internal surface damage in piping systems. In order to examine the effect of wall-thinning on the natural frequencies, the elastodynamic model of the fiber-reinforced polymer pipe is formulated using a wavelet-based finite element method. In this context, a new set of Hermite shape functions is developed. The generalized eigen value problem is solved and the natural frequencies are obtained for an fiber-reinforced polymer pipe with different depths and locations of the wall-thinning. Moreover, the effect of wall-thinning on the modal frequencies of the pipe was verified experimentally. Both the analytical and experimental results demonstrate the potential of using vibration signature to detect internal surface damage in fiber-reinforced polymer pipes.
Yehia A Khulief; Mohamed A El-Gebeily; Wasiu A Oke; Wael H Ahmed. Modal frequencies of fiber-reinforced polymer pipes with wall-thinning using a wavelet-based finite element model. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 2014, 229, 2377 -2386.
AMA StyleYehia A Khulief, Mohamed A El-Gebeily, Wasiu A Oke, Wael H Ahmed. Modal frequencies of fiber-reinforced polymer pipes with wall-thinning using a wavelet-based finite element model. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. 2014; 229 (13):2377-2386.
Chicago/Turabian StyleYehia A Khulief; Mohamed A El-Gebeily; Wasiu A Oke; Wael H Ahmed. 2014. "Modal frequencies of fiber-reinforced polymer pipes with wall-thinning using a wavelet-based finite element model." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 13: 2377-2386.
The prediction of flow rates at which the vibration-induced instability takes place in tubular heat exchangers due to cross flow is of major importance to the performance and service life of such equipment. In this paper, the semi-analytical model is developed and utilized to study the triangular tube patterns. The developed mathematical model is tuned with the experimentally measured fluid-elastic force coefficients. An experimental setup with water channel and instrumented test section is constructed. In this investigation, two test sections are constructed for both the normal triangular and the rotated triangular tube arrays. The developed scheme is utilized for predicting the critical flow velocities at the inception of flow-induced instability in the two triangular tube arrays. The results are compared to those obtained for two other bundle configurations, namely the square and rotated square arrays. The results of the two tube patterns are viewed in light of TEMA predictions. The comparisons demonstrated that TEMA predictions provided more conservative guidelines for all the configurations considered. Field application of the obtained results was successful in extending the service life of tube and shell heat exchangers beyond that predicted by TEMA.
Y. A. Khulief; S. A. Bashmal; S. A. Said; D. A. Al-Otaibi; K. M. Mansour. Prediction of Vibration-Induced Instability Due to Cross Flow in Heat Exchangers with Triangular Tube Arrays. Arabian Journal for Science and Engineering 2014, 39, 8209 -8219.
AMA StyleY. A. Khulief, S. A. Bashmal, S. A. Said, D. A. Al-Otaibi, K. M. Mansour. Prediction of Vibration-Induced Instability Due to Cross Flow in Heat Exchangers with Triangular Tube Arrays. Arabian Journal for Science and Engineering. 2014; 39 (11):8209-8219.
Chicago/Turabian StyleY. A. Khulief; S. A. Bashmal; S. A. Said; D. A. Al-Otaibi; K. M. Mansour. 2014. "Prediction of Vibration-Induced Instability Due to Cross Flow in Heat Exchangers with Triangular Tube Arrays." Arabian Journal for Science and Engineering 39, no. 11: 8209-8219.
Flexible rotor balancing, in general, relies to a great extent on physical insight into the modal nature of the unbalance response. The objective of this investigation is to develop a hybrid experimental/analytical technique for balancing high-speed flexible rotors. The developed technique adopts an approach that combines the finite element modeling, experimental modal analysis, vibration measurements, and mathematical identification. The modal imbalances are identified and then transformed to the nodal space, in order to determine a set of physical balancing masses at some selected correction planes. The developed method does not rely on trial runs. In addition, the method does not require operating the supercritical rotor in a high-speed balancing facility, while accounting for the contribution of higher significant modes. The developed scheme is applied to a multidisk, multibearing, high-speed flexible rotor, where the interaction between the rotor-bending operating deflections and the forces resulting from the residual unbalance are appreciable. Some new benchmark solutions and observations are reported. The applicability, reliability, and challenges that may be encountered in field applications are addressed.
Y. A. Khulief; M. A. Mohiuddin; Mohamed El-Gebeily. A New Method for Field-Balancing of High-Speed Flexible Rotors without Trial Weights. International Journal of Rotating Machinery 2014, 2014, 1 -11.
AMA StyleY. A. Khulief, M. A. Mohiuddin, Mohamed El-Gebeily. A New Method for Field-Balancing of High-Speed Flexible Rotors without Trial Weights. International Journal of Rotating Machinery. 2014; 2014 ():1-11.
Chicago/Turabian StyleY. A. Khulief; M. A. Mohiuddin; Mohamed El-Gebeily. 2014. "A New Method for Field-Balancing of High-Speed Flexible Rotors without Trial Weights." International Journal of Rotating Machinery 2014, no. : 1-11.
The need to devise a low-speed balancing method for balancing high-speed rotors was recognized and addressed. In this paper, a scheme that combines both the influence coefficients and modal balancing techniques is presented. The scheme is developed for low-speed balancing of high-speed rotors, and relies on knowledge of the modal characteristics of the rotor. The conditions for applicability of the method were stated in the light of the experientially estimated rotor deflection mode shapes. An experimental test rig of a flexible rotor was constructed to verify the applicability and reliability of the low-speed balancing scheme.
Y. A. Khulief; Wasiu Oke; M. A. Mohiuddin. Modally Tuned Influence Coefficients for Low-Speed Balancing of Flexible Rotors. Journal of Vibration and Acoustics 2013, 136, 024501 .
AMA StyleY. A. Khulief, Wasiu Oke, M. A. Mohiuddin. Modally Tuned Influence Coefficients for Low-Speed Balancing of Flexible Rotors. Journal of Vibration and Acoustics. 2013; 136 (2):024501.
Chicago/Turabian StyleY. A. Khulief; Wasiu Oke; M. A. Mohiuddin. 2013. "Modally Tuned Influence Coefficients for Low-Speed Balancing of Flexible Rotors." Journal of Vibration and Acoustics 136, no. 2: 024501.
This paper appraises the current status of research devoted to the problem of modeling impact in multibody systems. The paper presents a focused, yet coherent overview of the problem of modeling impulsive motions initiated by impacts in multibody systems in light of the reported literature, while highlighting the key research accomplishments, unresolved problems, and pending challenges. The paper begins with a brief overview of the mechanics of contact in two-body collisions, and then proceeds to review different approaches for modeling the dynamics of impact in rigid multibody mechanical systems and multibody systems of interconnected rigid and flexible bodies. The review concludes by shedding light on some pertinent computational considerations.
Y. A. Khulief. Modeling of Impact in Multibody Systems: An Overview. Journal of Computational and Nonlinear Dynamics 2012, 8, 021012 .
AMA StyleY. A. Khulief. Modeling of Impact in Multibody Systems: An Overview. Journal of Computational and Nonlinear Dynamics. 2012; 8 (2):021012.
Chicago/Turabian StyleY. A. Khulief. 2012. "Modeling of Impact in Multibody Systems: An Overview." Journal of Computational and Nonlinear Dynamics 8, no. 2: 021012.
Acoustic leak-detection techniques are proven to be effective and have been widely used in water-distribution systems for several decades. Most of the existing acoustic leak-detection techniques rely on external measurements of sound emitted from the turbulent jet of water escaping the pipe. Direct acoustic measurements through hydrophones, which travel inside the pipe with the flow, have been recently addressed as an efficient complementary leak-detection technique. This paper presents an experimental investigation that addresses the feasibility and potential of in-pipe acoustic measurements for leak detection. An experimental test rig was constructed to simulate a water transmission pipeline and permits different leak sizes, flow rates, and pressures. The acquired acoustic signals were analyzed; the feasibility and limitations of invoking in-pipe measurements for leak detection were addressed.
Y. A. Khulief; A. Khalifa; R. Ben Mansour; M. A. Habib. Acoustic Detection of Leaks in Water Pipelines Using Measurements inside Pipe. Journal of Pipeline Systems Engineering and Practice 2012, 3, 47 -54.
AMA StyleY. A. Khulief, A. Khalifa, R. Ben Mansour, M. A. Habib. Acoustic Detection of Leaks in Water Pipelines Using Measurements inside Pipe. Journal of Pipeline Systems Engineering and Practice. 2012; 3 (2):47-54.
Chicago/Turabian StyleY. A. Khulief; A. Khalifa; R. Ben Mansour; M. A. Habib. 2012. "Acoustic Detection of Leaks in Water Pipelines Using Measurements inside Pipe." Journal of Pipeline Systems Engineering and Practice 3, no. 2: 47-54.
Modal analysis of complex rotor-bearing systems using the finite element method (FEM) may become controversial when considering the tradeoff between geometric complexity and elastodynamic integrity of the FEM model. In this paper, the modal characteristics of an actual multi-impeller rotor-bearing system with complicated geometry are estimated and verified using two modeling schemes. The first scheme invokes a developed finite element elastodynamic model that accounts for gyroscopic effects, torsional-bending inertia coupling, internal material damping, shear and anisotropic bearings. In this model, the intricate details of the impeller were ignored, and only the inertial properties of the impeller disk are considered. The second scheme employs a general-purpose finite element code, wherein the complicated impeller geometry is included in lieu of ignoring some of the rotational effects and inertia coupling effects. The obtained results shed the light on the tradeoffs involved in modal analysis of complicated rotor systems using the FEM. Comparisons with experimental values showed that the first scheme, which adopts simplified impeller geometry while accounting for all the rotational effects is more accurate in estimating the modal characteristics of such complex rotor-bearing systems.
Y. A. Khulief; F. A. Al-Sulaiman; Abul Fazal M. Arif; R. Ben-Mansour; A. Al-Qutub; M. Anis. Computational Tradeoff in Modal Characteristics of Complex Rotor Systems Using FEM. Arabian Journal for Science and Engineering 2012, 37, 1653 -1664.
AMA StyleY. A. Khulief, F. A. Al-Sulaiman, Abul Fazal M. Arif, R. Ben-Mansour, A. Al-Qutub, M. Anis. Computational Tradeoff in Modal Characteristics of Complex Rotor Systems Using FEM. Arabian Journal for Science and Engineering. 2012; 37 (6):1653-1664.
Chicago/Turabian StyleY. A. Khulief; F. A. Al-Sulaiman; Abul Fazal M. Arif; R. Ben-Mansour; A. Al-Qutub; M. Anis. 2012. "Computational Tradeoff in Modal Characteristics of Complex Rotor Systems Using FEM." Arabian Journal for Science and Engineering 37, no. 6: 1653-1664.
The subject of the periodic vortex shedding behind bluff bodies, which exhibits oscillatory behaviour, is of direct relevance to many practical applications, e.g. pipelines and heat exchangers. Repetitive failures were occurring in associated piping components on the suction of a sales gas compressor. Available experimental investigations indicated the occurrences of vibrations at the predominant frequencies of 1500 and 3000 Hz in the compressor strainer pipes. Hence, this study is aimed at identifying the source of such high vibration levels. The study investigated the flow-induced vibrations in the compressor strainer pipe through numerical simulation of the flow in the pipe including the strainer, as well as structural modal analysis calculations for the strainer at steady-state conditions. Three different geometrical configurations were considered. The first strainer has a truncated-cone geometry with uniform size holes. The second is witch-hat geometry with uniform holes, while the third is a modified witch-hat configuration with non-uniform holes. The results obtained from the frequency analysis of the flow field downstream of strainers with the first two geometries indicated dominant amplitudes at 1500 Hz and appreciable excitations at its second harmonic. However, the results demonstrated that the dominant vibration amplitudes have been appreciably reduced for the third case of the modified witch-hat configuration with non-uniform holes.
Y Khulief; M A Habib; S A M Said; R Ben-Mansour; H M Badr; M Anis; A E Khalifa. Vortex shedding-free strainers. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 2011, 226, 91 -104.
AMA StyleY Khulief, M A Habib, S A M Said, R Ben-Mansour, H M Badr, M Anis, A E Khalifa. Vortex shedding-free strainers. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering. 2011; 226 (2):91-104.
Chicago/Turabian StyleY Khulief; M A Habib; S A M Said; R Ben-Mansour; H M Badr; M Anis; A E Khalifa. 2011. "Vortex shedding-free strainers." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 226, no. 2: 91-104.
The need to devise a low-speed balancing method for balancing high-speed rotors was recognized and addressed. In this paper, a scheme that combines both the influence coefficients and modal balancing techniques is presented. The scheme is developed for low-speed balancing of high-speed rotors, and relies on knowledge of modal characteristics of the rotor. The conditions for applicability of the method were stated in the light of the experientially estimated rotor deflection mode shapes. An experimental test rig of a flexible rotor was constructed to verify the applicability and reliability of the low-speed balancing scheme.
Y. A. Khulief; M. A. Mohiuddin. Modally-Tuned Influence Coefficients for Low-Speed Balancing of Flexible Rotors. Volume 8: 11th International Power Transmission and Gearing Conference; 13th International Conference on Advanced Vehicle and Tire Technologies 2011, 831 -837.
AMA StyleY. A. Khulief, M. A. Mohiuddin. Modally-Tuned Influence Coefficients for Low-Speed Balancing of Flexible Rotors. Volume 8: 11th International Power Transmission and Gearing Conference; 13th International Conference on Advanced Vehicle and Tire Technologies. 2011; ():831-837.
Chicago/Turabian StyleY. A. Khulief; M. A. Mohiuddin. 2011. "Modally-Tuned Influence Coefficients for Low-Speed Balancing of Flexible Rotors." Volume 8: 11th International Power Transmission and Gearing Conference; 13th International Conference on Advanced Vehicle and Tire Technologies , no. : 831-837.
Impulsive responses often arise in mechanical systems due to collision, impact, joint clearances, machine tool interaction, and material handling processes. Impulsive events take place during very short-lived intervals, and are normally associated with redistribution of momentum. The redistribution of momentum may take place instantaneously or during a very short interval, thus giving rise to discontinuities in the system's velocities. In this context, two modelling approaches are presented. The first approach adopts a smooth representation over the short-lived interval. In this case, the impulsive event is modelled while taking into consideration the mechanics of the contacting bodies. The second is a discontinuous dynamic model, in which the impulsive event is assumed to take place at an instant of time. The corresponding instantaneous redistribution of momentum results in jump discontinuities in the system's velocities, which are calculated to update the system state vector for starting the next interval. The merits of the two modelling approaches are stated in the light of numerical simulations.
Y.A. Khulief. Numerical Modelling of Impulsive Events in Mechanical Systems. International Journal of Modelling and Simulation 2010, 30, 80 -86.
AMA StyleY.A. Khulief. Numerical Modelling of Impulsive Events in Mechanical Systems. International Journal of Modelling and Simulation. 2010; 30 (1):80-86.
Chicago/Turabian StyleY.A. Khulief. 2010. "Numerical Modelling of Impulsive Events in Mechanical Systems." International Journal of Modelling and Simulation 30, no. 1: 80-86.
It has become evident that the modeling of the complex dynamics of fluidelastic forces that give rise to vibrations of tube bundles requires a great deal of experimental insight. Accordingly, the prediction of the flow-induced vibration due to unsteady cross-flow can be greatly aided by semi-analytical models, in which some coefficients are determined experimentally. A laboratory test rig with an instrumented test bundle is constructed to measure the fluidelastic coefficients to be used in conjunction with the mathematical model derived in Part I of this paper. The test rig admits two different test bundles, namely, the inline-square and 45deg rotated-square tube arrays. Measurements were conducted to identify the flow-induced dynamic coefficients. The developed scheme was utilized in predicting the onset of flow-induced vibrations in two configurations of tube bundles, and results were examined in the light of Tubular Exchange Manufacturers Association (TEMA) predictions. The comparison demonstrated that TEMA guidelines are more conservative in the two configurations considered.
S. A. Al-Kaabi; Y. A. Khulief; S. A. Said. Prediction of Flow-Induced Vibrations in Tubular Heat Exchangers—Part II: Experimental Investigation. Journal of Pressure Vessel Technology 2008, 131, 011302 .
AMA StyleS. A. Al-Kaabi, Y. A. Khulief, S. A. Said. Prediction of Flow-Induced Vibrations in Tubular Heat Exchangers—Part II: Experimental Investigation. Journal of Pressure Vessel Technology. 2008; 131 (1):011302.
Chicago/Turabian StyleS. A. Al-Kaabi; Y. A. Khulief; S. A. Said. 2008. "Prediction of Flow-Induced Vibrations in Tubular Heat Exchangers—Part II: Experimental Investigation." Journal of Pressure Vessel Technology 131, no. 1: 011302.