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Prof. Kyros Yakinthos
Department of Mechanical Engineering, Laboratory of Fluid Mechanics and Turbomachinery, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece

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Research Keywords & Expertise

0 Turbulence Modeling
0 Computational Fluid Dynamics
0 Transitional boundary layers
0 Active flow control on wings
0 Waste heat management technologies for aeroengines

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Computational Fluid Dynamics
Turbulence Modeling

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Journal article
Published: 06 January 2021 in Aerospace
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The current study presents a low-fidelity, quasi-3D aerodynamic analysis method for Blended-Wing-Body (BWB) Unmanned Aerial Vehicle (UAV) configurations. A tactical BWB UAV experimental prototype is used as a reference platform. The method utilizes 2D panel method analyses and theoretical aerodynamic calculations to rapidly compute lift and pitching moment coefficients. The philosophy and the underlying theoretical and semi-empirical equations of the proposed method are extensively described. Corrections related to control surfaces deflection and ground effect are also suggested, so that the BWB pitching stability and trimming calculations can be supported. The method is validated against low-fidelity 3D aerodynamic analysis methods and high-fidelity, Computational Fluid Dynamics (CFD) results for various BWB configurations. The validation procedures show that the proposed method is considerably more accurate than existing low-fidelity ones, can provide predictions for both lift and pitching moment coefficients and requires far less computational resources and time when compared to CFD modeling. Hence, it can serve as a valuable aerodynamics and stability analysis tool for BWB UAV configurations.

ACS Style

Pericles Panagiotou; Thomas Dimopoulos; Stylianos Dimitriou; Kyros Yakinthos. Quasi-3D Aerodynamic Analysis Method for Blended-Wing-Body UAV Configurations. Aerospace 2021, 8, 13 .

AMA Style

Pericles Panagiotou, Thomas Dimopoulos, Stylianos Dimitriou, Kyros Yakinthos. Quasi-3D Aerodynamic Analysis Method for Blended-Wing-Body UAV Configurations. Aerospace. 2021; 8 (1):13.

Chicago/Turabian Style

Pericles Panagiotou; Thomas Dimopoulos; Stylianos Dimitriou; Kyros Yakinthos. 2021. "Quasi-3D Aerodynamic Analysis Method for Blended-Wing-Body UAV Configurations." Aerospace 8, no. 1: 13.

Journal article
Published: 04 December 2020 in Aerospace Science and Technology
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The current study presents the layout optimization of a tactical, fixed-wing UAV, during the early stages of the preliminary design. The reference platform is a Blended-Wing-Body (BWB) configuration, whose mission is the aerial delivery of cargo and lifesaving supplies. The optimization is conducted by means of Computational Fluid Dynamics (CFD) using the Taguchi experimental design method. The aspect ratio, taper ratio and sweep angle are defined as the key design parameters. An L9 orthogonal array is used to investigate the effect of those parameters on the maximum velocity, the takeoff runway and the gross takeoff weight, which serve as the performance criteria. The combinations that maximize the top speed, minimize the takeoff runway and the gross takeoff weight are extracted. Furthermore, an Analysis of Variance (ANOVA) is carried out to assess the contribution of each design variable to the performance criteria.

ACS Style

S. Kapsalis; P. Panagiotou; K. Yakinthos. CFD-aided optimization of a tactical Blended-Wing-Body UAV platform using the Taguchi method. Aerospace Science and Technology 2020, 108, 106395 .

AMA Style

S. Kapsalis, P. Panagiotou, K. Yakinthos. CFD-aided optimization of a tactical Blended-Wing-Body UAV platform using the Taguchi method. Aerospace Science and Technology. 2020; 108 ():106395.

Chicago/Turabian Style

S. Kapsalis; P. Panagiotou; K. Yakinthos. 2020. "CFD-aided optimization of a tactical Blended-Wing-Body UAV platform using the Taguchi method." Aerospace Science and Technology 108, no. : 106395.

Research article
Published: 16 April 2020 in Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
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In this work, a 3D numerical study on the influence of the spanwise distribution of tubercles on a unmanned aerial vehicle wing is presented. The idea of using tubercles in aeronautics comes from the humpback whale (Megaptera novaeangliae) which has a characteristic flipper, with a spanwise scalloped leading edge, creating an almost sinusoidal shape, consisting of bumps called tubercles. The whale uses this layout in order to achieve high underwater maneuverability. Early experimental research showed a great potential in enhancing the 3D aerodynamic characteristics of a wing. Most of the existing experimental results concern infinite wings (2D) models and are accompanied with substantial loss in lift and increase in drag in pre-stall region. On the other hand, 3D finite models have displayed a better overall aerodynamic performance (increased lift and moment, but also, decreased drag). At a range of Reynolds number between 500,000 and 1,000,000 (based on the mean chord of the flipper), tubercles act as virtual fences, introducing a pair of counter rotating vortices that delays the stall of the flipper, a phenomenon that the whales exploit to perform sharp turns and catch their prey. The aforementioned Reynolds number range is the same as the operational Reynolds number for typical unmanned aerial vehicles. To assess the influence of the tubercles installation on UAV wings, a full 3D computational study is carried-out with the use of CFD tools which at a first phase are validated and calibrated with the available literature experimental data. Then, computations are performed for different spanwise tubercles distributions. The results show that there is a noticeable potential on controlling the flow on the wings of a UAV operating in a Reynolds number range between 500,000 and 1,000,000 (based on UAV’s wing mean chord), which can lead to an aerodynamic performance and efficiency increase.

ACS Style

Charalampos Papadopoulos; Vasilis Katsiadramis; Kyros Yakinthos. Influence of tubercles’ spanwise distribution on swept wings for unmanned aerial vehicles. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 2020, 235, 95 -103.

AMA Style

Charalampos Papadopoulos, Vasilis Katsiadramis, Kyros Yakinthos. Influence of tubercles’ spanwise distribution on swept wings for unmanned aerial vehicles. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering. 2020; 235 (1):95-103.

Chicago/Turabian Style

Charalampos Papadopoulos; Vasilis Katsiadramis; Kyros Yakinthos. 2020. "Influence of tubercles’ spanwise distribution on swept wings for unmanned aerial vehicles." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 235, no. 1: 95-103.

Journal article
Published: 22 November 2019 in Aerospace Science and Technology
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The present work aims in providing guidelines for the aerodynamic and performance optimization of fixed-wing Unmanned Aerial Vehicles (UAVs) that operate in the low-speed subsonic regime. Using a combination of textbook methods, low-fidelity and high-fidelity aerodynamic analysis tools, an aerodynamics and drag breakdown analysis is made on a reference UAV wing platform. Then, a complete drag bookkeeping study is made on the corresponding reference UAV configuration, providing the contribution of each part to the total drag budget for various angles of attack. Using the results of the aerodynamic investigations as guide, a thorough drag-reduction technologies screening is made based on existing literature, with the discussion also including integration and realization issues. Concluding, the most promising technologies are proposed taking into account the potential benefits as well as the technology readiness. The current work can serve as a base for future, more detailed, aerodynamic and performance enhancement studies for UAVs.

ACS Style

P. Panagiotou; K. Yakinthos. Aerodynamic efficiency and performance enhancement of fixed-wing UAVs. Aerospace Science and Technology 2019, 99, 105575 .

AMA Style

P. Panagiotou, K. Yakinthos. Aerodynamic efficiency and performance enhancement of fixed-wing UAVs. Aerospace Science and Technology. 2019; 99 ():105575.

Chicago/Turabian Style

P. Panagiotou; K. Yakinthos. 2019. "Aerodynamic efficiency and performance enhancement of fixed-wing UAVs." Aerospace Science and Technology 99, no. : 105575.

E technical paper
Published: 06 November 2018 in Aircraft Engineering and Aerospace Technology
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Purpose The purpose of this paper is to present the preliminary design of a medium altitude long endurance (MALE) unmanned aerial vehicle (UAV), focusing on the interaction between the aerodynamic and the structural design studies. Design/methodology/approach The classic layout theory was used, adjusted for the needs of unmanned aircraft, including aerodynamic calculations, presizing methods and CFD, to estimate key aerodynamic and stability coefficients. Considering the structural aspects, a combination of layout, finite element methods and custom parameterized design tools were used, allowing automatic reshapes of the skin and the internal structural parts, which are mainly made of composite materials. Interaction loops were defined between the aforementioned studies to optimize the performance of the aerial vehicle, maximize the aerodynamic efficiency and reduce the structural weight. Findings The complete design procedure of a UAV is shown, starting from the final stages of conceptual design, up to the point where the detail design and mechanical drawings initiated. Practical implications This paper presents a complete view of a design study of a MALE UAV, which was successfully constructed and flight-tested. Originality/value This study presents a complete, synergetic approach between the configuration layout, aerodynamic and structural aspects of a MALE UAV.

ACS Style

Pericles Panagiotou; Efstratios Giannakis; Georgios Savaidis; Kyros Yakinthos. Aerodynamic and structural design for the development of a MALE UAV. Aircraft Engineering and Aerospace Technology 2018, 90, 1077 -1087.

AMA Style

Pericles Panagiotou, Efstratios Giannakis, Georgios Savaidis, Kyros Yakinthos. Aerodynamic and structural design for the development of a MALE UAV. Aircraft Engineering and Aerospace Technology. 2018; 90 (7):1077-1087.

Chicago/Turabian Style

Pericles Panagiotou; Efstratios Giannakis; Georgios Savaidis; Kyros Yakinthos. 2018. "Aerodynamic and structural design for the development of a MALE UAV." Aircraft Engineering and Aerospace Technology 90, no. 7: 1077-1087.

Conference paper
Published: 15 September 2018 in 22nd AIAA International Space Planes and Hypersonics Systems and Technologies Conference
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ACS Style

Chris Bliamis; Pericles Panagiotou; Kyros Yakinthos. Hypersonic vehicle control concept using an active shock bump technique. 22nd AIAA International Space Planes and Hypersonics Systems and Technologies Conference 2018, 1 .

AMA Style

Chris Bliamis, Pericles Panagiotou, Kyros Yakinthos. Hypersonic vehicle control concept using an active shock bump technique. 22nd AIAA International Space Planes and Hypersonics Systems and Technologies Conference. 2018; ():1.

Chicago/Turabian Style

Chris Bliamis; Pericles Panagiotou; Kyros Yakinthos. 2018. "Hypersonic vehicle control concept using an active shock bump technique." 22nd AIAA International Space Planes and Hypersonics Systems and Technologies Conference , no. : 1.

Journal article
Published: 06 September 2018 in Energy
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Energy saving technologies are of prior importance to European environmental legislation. Gas turbines is a widely used technology, but is also considered a technology of important environmental footprint. Recuperation technology can be applied in gas turbines applications in order to achieve higher efficiency and reduced fuel consumption. In this work three different thermodynamic cycles are under investigation: the conventional recuperative cycle, the alternative and the SHR. All of these cycles have one or more heat exchangers integrated at different positions inside the gas turbine. In recuperative cycles the turbine inlet temperature is usually high, in order to achieve a beneficial temperature difference for recuperation. However, as this temperature increases the demanded mass flow for cooling the turbines gets higher. In order to obtain realistic results of high accuracy, the coolant mass flow cannot be neglected and must be carefully considered. In this paper, the required coolant mass flow is calculated for each cycle and for an extended range of operational conditions. The efficiency penalty due to the extracted air from the compressor is also calculated and presented. Different materials technology level is taken into account and therefore three allowable metal temperatures are considered for the calculations. The demanded coolant mass flow is calculated based on Young and Wilcock (2002). In order to underline the importance of taking into account the demanded coolant flow, an analysis of the performance of a helicopter engine is presented. The results show that both the thermal efficiency and the specific fuel consumption are affected when turbine blade cooling is taken into account.

ACS Style

Christina Salpingidou; Dimitra Tsakmakidou; Zinon Vlahostergios; Dimitrios Misirlis; Michael Flouros; Kyros Yakinthos. Analysis of turbine blade cooling effect on recuperative gas turbines cycles performance. Energy 2018, 164, 1271 -1285.

AMA Style

Christina Salpingidou, Dimitra Tsakmakidou, Zinon Vlahostergios, Dimitrios Misirlis, Michael Flouros, Kyros Yakinthos. Analysis of turbine blade cooling effect on recuperative gas turbines cycles performance. Energy. 2018; 164 ():1271-1285.

Chicago/Turabian Style

Christina Salpingidou; Dimitra Tsakmakidou; Zinon Vlahostergios; Dimitrios Misirlis; Michael Flouros; Kyros Yakinthos. 2018. "Analysis of turbine blade cooling effect on recuperative gas turbines cycles performance." Energy 164, no. : 1271-1285.

Research article
Published: 24 August 2018 in Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
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In this work, the development of a conceptual design methodology of an innovative aircraft configuration, known as box wing, is presented. A box wing aircraft is based on a continuous-surface nonplanar wing formation with no wing-tips. The A320 medium range conventional cantilever wing aircraft is used as both the reference aircraft and the main competitor of the box wing aircraft. Based on the A320 characteristics and dimensions, a complete aerodynamic analysis of the box wing configuration is made by means of layout design and computational fluid dynamics studies, highlighting the aerodynamic and operating advantages of the box wing configuration compared to the A320 aircraft. The aspect ratio and the Oswald factor of a box wing aircraft differ significantly from the corresponding ones of A320 and provide increased aerodynamic performance. The increased aerodynamic performance leads by consequence, to lower fuel consumption, thus allowing longer range for the same payload or greater payload for the same range, contributing to the efforts for greener environment. In this work, the design methodology begins by estimating the critical initial design parameters, such as aspect ratio, dihedral angle, sweep angle, and taper ratio, which are continuously refined via an iterative process based on a conceptual design study. Various flying scenarios are studied using computational fluid dynamics and analytical calculations, in order to compare the performance of the box wing and the conventional A320, having always the same mission and payload conditions. The conceptual results show that the novel box wing configuration has considerable aerodynamic performance advantages compared to the conventional A320 aircraft.

ACS Style

Pavlos Kaparos; Charalampos Papadopoulos; Kyros Yakinthos. Conceptual design methodology of a box wing aircraft: A novel commercial airliner. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 2018, 232, 2651 -2662.

AMA Style

Pavlos Kaparos, Charalampos Papadopoulos, Kyros Yakinthos. Conceptual design methodology of a box wing aircraft: A novel commercial airliner. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering. 2018; 232 (14):2651-2662.

Chicago/Turabian Style

Pavlos Kaparos; Charalampos Papadopoulos; Kyros Yakinthos. 2018. "Conceptual design methodology of a box wing aircraft: A novel commercial airliner." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 14: 2651-2662.

Conference paper
Published: 24 June 2018 in 2018 Applied Aerodynamics Conference
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ACS Style

Pericles Panagiotou; Michael Efthymiadis; Dimitrios Mitridis; Kyros Yakinthos. A CFD-aided investigation of the morphing winglet concept for the performance optimization of fixed-wing MALE UAVs. 2018 Applied Aerodynamics Conference 2018, 1 .

AMA Style

Pericles Panagiotou, Michael Efthymiadis, Dimitrios Mitridis, Kyros Yakinthos. A CFD-aided investigation of the morphing winglet concept for the performance optimization of fixed-wing MALE UAVs. 2018 Applied Aerodynamics Conference. 2018; ():1.

Chicago/Turabian Style

Pericles Panagiotou; Michael Efthymiadis; Dimitrios Mitridis; Kyros Yakinthos. 2018. "A CFD-aided investigation of the morphing winglet concept for the performance optimization of fixed-wing MALE UAVs." 2018 Applied Aerodynamics Conference , no. : 1.

Conference paper
Published: 24 June 2018 in 2018 Flow Control Conference
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ACS Style

Pavlos Kaparos; Savvas Koltsakidis; Pericles Panagiotou; Kyros Yakinthos. Experimental investigation of DBD plasma actuators on a BWB aerial vehicle model. 2018 Flow Control Conference 2018, 1 .

AMA Style

Pavlos Kaparos, Savvas Koltsakidis, Pericles Panagiotou, Kyros Yakinthos. Experimental investigation of DBD plasma actuators on a BWB aerial vehicle model. 2018 Flow Control Conference. 2018; ():1.

Chicago/Turabian Style

Pavlos Kaparos; Savvas Koltsakidis; Pericles Panagiotou; Kyros Yakinthos. 2018. "Experimental investigation of DBD plasma actuators on a BWB aerial vehicle model." 2018 Flow Control Conference , no. : 1.

Conference paper
Published: 11 June 2018 in Volume 5C: Heat Transfer
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The present work is focused on the optimization of the performance characteristics of a recuperator specifically designed for aero engine applications, targeting the reduction of specific fuel consumption and taking into consideration aero engine geometrical constraints and limitations. The recuperator design was based on the elliptically profiled tubular heat exchanger which was developed and invented by MTU Aero Engines AG. For the specific fuel consumption investigations the Intercooled Recuperated Aero engine cycle, combining both intercooling and recuperation, was considered. The optimization was performed with the development of a recuperator surrogate model, capable to incorporate major recuperator geometrical features. A large number of recuperator design scenarios was assessed, in which additional design criteria and constraints were applied. Thus, a significantly large recuperator design space was covered resulting to the identification of feasible recuperator designs providing beneficial effect on the Intercooled Recuperated Aero engine leading to reduced specific fuel consumption and weight.

ACS Style

Christina Salpingidou; Dimitrios Misirlis; Zinon Vlahostergios; Michael Flouros; Fabian Donus; Kyros Yakinthos. Design Optimization of Heat Exchangers for Aero Engines With the Use of a Surrogate Model Incorporating Performance Characteristics and Geometrical Constraints. Volume 5C: Heat Transfer 2018, 1 .

AMA Style

Christina Salpingidou, Dimitrios Misirlis, Zinon Vlahostergios, Michael Flouros, Fabian Donus, Kyros Yakinthos. Design Optimization of Heat Exchangers for Aero Engines With the Use of a Surrogate Model Incorporating Performance Characteristics and Geometrical Constraints. Volume 5C: Heat Transfer. 2018; ():1.

Chicago/Turabian Style

Christina Salpingidou; Dimitrios Misirlis; Zinon Vlahostergios; Michael Flouros; Fabian Donus; Kyros Yakinthos. 2018. "Design Optimization of Heat Exchangers for Aero Engines With the Use of a Surrogate Model Incorporating Performance Characteristics and Geometrical Constraints." Volume 5C: Heat Transfer , no. : 1.

Proceedings article
Published: 11 June 2018 in Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems
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This work is focused on investigations of Intercooled Recuperation configurations for aero engines. The investigated configurations were the Conventional Recuperation, where the recuperator was placed downstream the low-pressure turbine (LPT), the Alternative Recuperation, where the recuperator was mounted between the intermediate pressure turbine (IPT) and LPT, and the Staged Heat Recovery concept, in which two recuperators were mounted, one between IPT and LPT and the other downstream the LPT. These concepts were further assessed with the use of an additional combustor between IPT and LPT. All recuperator concepts that have been developed within the framework of various research projects by Aristotle University of Thessaloniki and MTU Aero engines AG were utilized, named as the NEWAC, CORN and STARTREC concepts. Additionally, a new recuperator design was introduced using a secondary fluid as heat transfer medium. The configurations thermodynamic assessment was focused on specific fuel consumption reduction, while the configurations effect on NOx emissions was also investigated. The results showed that the most promising recuperator concept, with respect to low TSFC values compared with a reference GTF engine of 2050 year technology level, is the recuperator with the secondary fluid heat transfer medium.

ACS Style

Christina Salpingidou; Zinon Vlahostergios; Dimitrios Misirlis; Michael Flouros; Fabian Donus; Kyros Yakinthos. Investigation and Assessment of the Performance of Various Recuperative Cycles Based on the Intercooled Recuperation Concept. Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems 2018, 1 .

AMA Style

Christina Salpingidou, Zinon Vlahostergios, Dimitrios Misirlis, Michael Flouros, Fabian Donus, Kyros Yakinthos. Investigation and Assessment of the Performance of Various Recuperative Cycles Based on the Intercooled Recuperation Concept. Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems. 2018; ():1.

Chicago/Turabian Style

Christina Salpingidou; Zinon Vlahostergios; Dimitrios Misirlis; Michael Flouros; Fabian Donus; Kyros Yakinthos. 2018. "Investigation and Assessment of the Performance of Various Recuperative Cycles Based on the Intercooled Recuperation Concept." Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems , no. : 1.

Journal article
Published: 10 April 2018 in Journal of Engineering for Gas Turbines and Power
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This work presents an exergy analysis and performance assessment of three recuperative thermodynamic cycles for gas turbine applications. The first configuration is the conventional recuperative (CR) cycle in which a heat exchanger is placed after the power turbine (PT). In the second configuration, referred as alternative recuperative (AR) cycle, a heat exchanger is placed between the high pressure and the PT, while in the third configuration, referred as staged heat recovery (SHR) cycle, two heat exchangers are employed, the primary one between the high and PTs and the secondary at the exhaust, downstream the PT. The first part of this work is focused on a detailed exergetic analysis on conceptual gas turbine cycles for a wide range of heat exchanger performance parameters. The second part focuses on the implementation of recuperative cycles in aero engines, focused on the MTU-developed intercooled recuperative aero (IRA) engine concept, which is based on a conventional recuperation approach. Exergy analysis is applied on specifically developed IRA engine derivatives using both alternative and SHR recuperation concepts to quantify energy exploitation and exergy destruction per cycle and component, showing the amount of exergy that is left unexploited, which should be targeted in future optimization actions.

ACS Style

Christina Salpingidou; Dimitrios Misirlis; Zinon Vlahostergios; Stefan Donnerhack; Michael Flouros; Apostolos Goulas; Kyros Yakinthos. Exergy Analysis and Performance Assessment for Different Recuperative Thermodynamic Cycles for Gas Turbine Applications. Journal of Engineering for Gas Turbines and Power 2018, 140, 071701 .

AMA Style

Christina Salpingidou, Dimitrios Misirlis, Zinon Vlahostergios, Stefan Donnerhack, Michael Flouros, Apostolos Goulas, Kyros Yakinthos. Exergy Analysis and Performance Assessment for Different Recuperative Thermodynamic Cycles for Gas Turbine Applications. Journal of Engineering for Gas Turbines and Power. 2018; 140 (7):071701.

Chicago/Turabian Style

Christina Salpingidou; Dimitrios Misirlis; Zinon Vlahostergios; Stefan Donnerhack; Michael Flouros; Apostolos Goulas; Kyros Yakinthos. 2018. "Exergy Analysis and Performance Assessment for Different Recuperative Thermodynamic Cycles for Gas Turbine Applications." Journal of Engineering for Gas Turbines and Power 140, no. 7: 071701.

Journal article
Published: 01 January 2018 in Progress in Computational Fluid Dynamics, An International Journal
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A computational study regarding the accurate modelling of the unsteady flow over a slender delta-wing and the vortex breakdown (VB) identification by adopting a Reynolds-stress turbulence model is presented. The VB is identified by the pressure distributions, the stagnation point inside the vortex core and the vorticity development over the delta-wing. Additionally, the whole range of the unsteady flow field kinetic energy, which is divided into two regions, is calculated. The first region is related to the modelled turbulent small-scales and the second to the resolved large-scales, which are produced due to the VB. The distributions of the small-scale, the large-scale and the total kinetic energy along the vortex core are presented, providing information regarding their development during VB. The results show that the adoption of URANS with an advanced/sophisticated turbulence model is able to identify and describe with consistency the VB onset and its development over a slender delta-wing.

ACS Style

Zinon Vlahostergios; Dimitrios Komnos; Kyros Yakinthos. Modelling of vortex breakdown and calculation of large-scale kinetic energy on a slender delta wing using URANS and Reynolds-stress modelling. Progress in Computational Fluid Dynamics, An International Journal 2018, 18, 347 .

AMA Style

Zinon Vlahostergios, Dimitrios Komnos, Kyros Yakinthos. Modelling of vortex breakdown and calculation of large-scale kinetic energy on a slender delta wing using URANS and Reynolds-stress modelling. Progress in Computational Fluid Dynamics, An International Journal. 2018; 18 (6):347.

Chicago/Turabian Style

Zinon Vlahostergios; Dimitrios Komnos; Kyros Yakinthos. 2018. "Modelling of vortex breakdown and calculation of large-scale kinetic energy on a slender delta wing using URANS and Reynolds-stress modelling." Progress in Computational Fluid Dynamics, An International Journal 18, no. 6: 347.

Journal article
Published: 01 January 2018 in Progress in Computational Fluid Dynamics, An International Journal
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ACS Style

Zinon Vlahostergios; Dimitrios Komnos; Kyros Yakinthos. Modelling of vortex breakdown and calculation of large-scale kinetic energy on a slender delta wing using URANS and Reynolds-stress modelling. Progress in Computational Fluid Dynamics, An International Journal 2018, 18, 347 .

AMA Style

Zinon Vlahostergios, Dimitrios Komnos, Kyros Yakinthos. Modelling of vortex breakdown and calculation of large-scale kinetic energy on a slender delta wing using URANS and Reynolds-stress modelling. Progress in Computational Fluid Dynamics, An International Journal. 2018; 18 (6):347.

Chicago/Turabian Style

Zinon Vlahostergios; Dimitrios Komnos; Kyros Yakinthos. 2018. "Modelling of vortex breakdown and calculation of large-scale kinetic energy on a slender delta wing using URANS and Reynolds-stress modelling." Progress in Computational Fluid Dynamics, An International Journal 18, no. 6: 347.

Journal article
Published: 01 November 2017 in Aerospace
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An experimental investigation of the wake of an Unmanned Aerial Vehicle (UAV) model using flow visualization techniques and a 3D Laser Doppler Anemometry (LDA) system is presented in this work. Emphasis is given on the flow field at the wingtip and the investigation of the tip vortices. A comparison of the velocity field is made with and without winglet devices installed at the wingtips. The experiments are carried out in a closed-circuit subsonic wind tunnel. The flow visualization techniques include smoke-wire and smoke-probe experiments to identify the flow phenomena, whereas for accurately measuring the velocity field point measurements are conducted using the LDA system. Apart from the measured velocities, vorticity and circulation quantities are also calculated and compared for the two cases. The results help to provide a more detailed view of the flow field around the UAV and indicate the winglets’ significant contribution to the deconstruction of wing-tip vortex structures.

ACS Style

Pericles Panagiotou; George Ioannidis; Ioannis Tzivinikos; Kyros Yakinthos. Experimental Investigation of the Wake and the Wingtip Vortices of a UAV Model. Aerospace 2017, 4, 53 .

AMA Style

Pericles Panagiotou, George Ioannidis, Ioannis Tzivinikos, Kyros Yakinthos. Experimental Investigation of the Wake and the Wingtip Vortices of a UAV Model. Aerospace. 2017; 4 (4):53.

Chicago/Turabian Style

Pericles Panagiotou; George Ioannidis; Ioannis Tzivinikos; Kyros Yakinthos. 2017. "Experimental Investigation of the Wake and the Wingtip Vortices of a UAV Model." Aerospace 4, no. 4: 53.

Conference paper
Published: 26 June 2017 in Volume 2A: Turbomachinery
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Targeting the development of more efficient aero engine designs, various concepts have been considered through the previous years, among which is the Intercooled Recuperative Aero engine (IRA) concept. In the IRA concept a system of heat exchangers is mounted in the hot-gas exhaust nozzle, downstream of the low-pressure turbine focusing on the exploitation of the waste heat exhaust gasses for preheating the compressor discharge air just before the latter enters the combustion chamber, resulting in fuel consumption and pollutants emission reduction. In the present work a new heat exchanger design for use as a recuperator is proposed for possible implementation in the IRA engine, based on an annular configuration design which is more easily integrated in an aero engine. The new recuperator external pressure losses are computationally and experimentally investigated for laboratory conditions, providing very good agreement. Additionally, the pressure losses just before the recuperator were further minimized by introducing riblet films inside the exhaust conical nozzle. The optimized recuperator characteristics were included in a thermodynamic analysis of the IRA engine and it was shown that considerable improvement in fuel consumption and pollutant emissions reduction could be achieved.

ACS Style

Zinon Vlahostergios; Dimitrios Misirlis; Michael Flouros; Christina Salpingidou; Stefan Donnerhack; Apostolos Goulas; Kyros Yakinthos. Development, Numerical Investigation and Experimental Validation of a New Recuperator Design for Aero Engines Applications. Volume 2A: Turbomachinery 2017, 1 .

AMA Style

Zinon Vlahostergios, Dimitrios Misirlis, Michael Flouros, Christina Salpingidou, Stefan Donnerhack, Apostolos Goulas, Kyros Yakinthos. Development, Numerical Investigation and Experimental Validation of a New Recuperator Design for Aero Engines Applications. Volume 2A: Turbomachinery. 2017; ():1.

Chicago/Turabian Style

Zinon Vlahostergios; Dimitrios Misirlis; Michael Flouros; Christina Salpingidou; Stefan Donnerhack; Apostolos Goulas; Kyros Yakinthos. 2017. "Development, Numerical Investigation and Experimental Validation of a New Recuperator Design for Aero Engines Applications." Volume 2A: Turbomachinery , no. : 1.

Conference paper
Published: 26 June 2017 in Volume 2A: Turbomachinery
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This work presents an exergy analysis and performance assessment of three recuperative thermodynamic cycles for gas turbine applications. The first configuration is the conventional recuperative cycle in which a heat exchanger is placed after the power turbine. In the second configuration, referred as alternative recuperative cycle, a heat exchanger is placed between the high pressure and the power turbine, while in the third configuration, referred as staged heat recovery cycle, two heat exchangers are employed, the primary one between the high and power turbines and the secondary at the exhaust, downstream the power turbine. The first part of this work is focused on a detailed exergetic analysis on conceptual gas turbine cycles for a wide range of heat exchanger performance parameters. The second part focuses on the implementation of recuperative cycles in aero engines, focused on the MTU-developed Intercooled Recuperative Aero (IRA) engine concept, which is based on a conventional recuperation approach. Exergy analysis is applied on specifically developed IRA engine derivatives using both alternative and staged heat recovery recuperation concepts to quantify energy exploitation and exergy destruction per cycle and component, showing the amount of exergy that is left unexploited, which should be targeted in future optimization actions.

ACS Style

Christina Salpingidou; Dimitrios Misirlis; Zinon Vlahostergios; Stefan Donnerhack; Michael Flouros; Apostolos Goulas; Kyros Yakinthos. Exergy Analysis and Performance Assessment for Different Recuperative Thermodynamic Cycles for Gas Turbine Applications. Volume 2A: Turbomachinery 2017, 1 .

AMA Style

Christina Salpingidou, Dimitrios Misirlis, Zinon Vlahostergios, Stefan Donnerhack, Michael Flouros, Apostolos Goulas, Kyros Yakinthos. Exergy Analysis and Performance Assessment for Different Recuperative Thermodynamic Cycles for Gas Turbine Applications. Volume 2A: Turbomachinery. 2017; ():1.

Chicago/Turabian Style

Christina Salpingidou; Dimitrios Misirlis; Zinon Vlahostergios; Stefan Donnerhack; Michael Flouros; Apostolos Goulas; Kyros Yakinthos. 2017. "Exergy Analysis and Performance Assessment for Different Recuperative Thermodynamic Cycles for Gas Turbine Applications." Volume 2A: Turbomachinery , no. : 1.

Conference paper
Published: 02 June 2017 in 35th AIAA Applied Aerodynamics Conference
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ACS Style

Pericles Panagiotou; Kyros Yakinthos. Parametric aerodynamic study of Blended-Wing-Body platforms at low subsonic speeds for UAV applications. 35th AIAA Applied Aerodynamics Conference 2017, 1 .

AMA Style

Pericles Panagiotou, Kyros Yakinthos. Parametric aerodynamic study of Blended-Wing-Body platforms at low subsonic speeds for UAV applications. 35th AIAA Applied Aerodynamics Conference. 2017; ():1.

Chicago/Turabian Style

Pericles Panagiotou; Kyros Yakinthos. 2017. "Parametric aerodynamic study of Blended-Wing-Body platforms at low subsonic speeds for UAV applications." 35th AIAA Applied Aerodynamics Conference , no. : 1.

Journal article
Published: 16 May 2017 in Journal of Engineering for Gas Turbines and Power
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Oil system architecture in aero engines has remained almost the same for the last 35 years. At least one mechanically-driven oil feed pump is responsible for distributing pressurized oil into the bearing chambers and several scavenge pumps, also mechanically driven, are responsible for evacuating the bearing chambers from the oil and air mixture. Air is used as the sealing medium in bearing chambers and is the dominant medium in terms of volume occupation and expansion phenomena. In order to simplify the oil system architecture, improve the system's reliability with less mechanical parts, and also decrease weight, an ejector system has been designed for scavenging bearing chambers. In Flouros et al. (2013, “Ejector Scavenging of Bearing Chambers. A Numerical and Experimental Investigation,” ASME J. Eng. Gas Turbines Power, 135(8), p. 081602), an ejector system was presented which used aviation oil (MIL-PRF-23699 Std.) as the primary medium. In the course of further development, the original design was modified leading to a much smaller ejector. This ejector was tested in the rig using alternatively pressurized air or pressurized oil as primary medium. Additionally, three in-house developed primary nozzle (jet) designs were introduced and tested. The design of an ejector for application with compressible or incompressible media was supported through the development of an analysis tool. A momentum-based efficiency function is proposed herein and enables comparisons among different operating cases. Finally, ANSYS cfx (ANSYS, 2014, “ANSYS® CFX, Release 14.0,” ANSYS Inc., Canonsburg, PA) was used to carry out the numerical analysis. Similar to the ejector described in Flouros et al. (2013, “Ejector Scavenging of Bearing Chambers. A Numerical and Experimental Investigation,” ASME J. Eng. Gas Turbines Power, 135(8), p. 081602), the new design was also manufactured out of pure quartz glass to enable optical access. Through suitable instrumentation for pressures, temperatures, and air/oil flows, the performance characteristics of the new ejector were assessed and were compared to the analytic and numerical results. This work was partly funded by the German government within the research program Lufo4 (Luftfahrtforschungsprogramm 4/Aeronautical Research Program 4).

ACS Style

Michael Flouros; Christina Salpingidou; Kyros Yakinthos; Markus Hirschmann; Francois Cottier. Ejector Application for Scavenging of an Aero Engine Bearing Chamber. Journal of Engineering for Gas Turbines and Power 2017, 139, 101202 .

AMA Style

Michael Flouros, Christina Salpingidou, Kyros Yakinthos, Markus Hirschmann, Francois Cottier. Ejector Application for Scavenging of an Aero Engine Bearing Chamber. Journal of Engineering for Gas Turbines and Power. 2017; 139 (10):101202.

Chicago/Turabian Style

Michael Flouros; Christina Salpingidou; Kyros Yakinthos; Markus Hirschmann; Francois Cottier. 2017. "Ejector Application for Scavenging of an Aero Engine Bearing Chamber." Journal of Engineering for Gas Turbines and Power 139, no. 10: 101202.