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Effects of surface roughness on the aerodynamic performance of a high subsonic compressor airfoil at low Reynolds number

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Chinese Journal of Aeronautics 2021年第3期34卷 71-81页

作者： Mingyang WANG Chengwu YANG Ziliang LI Shengfeng ZHAO Yanfeng ZHANG Xin’gen LU Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The aerodynamic performance of compressor airfoil is significantly affected by the surface roughness at low Reynolds number(Re).In the present study,numerical simulations have been conducted to investigate the impact of surface roughness on the profile loss of a high subsonic compressor airfoil at Re=1.5×10^(5).Four roughness locations,covering 10%,30%,50%and 100%of the suction surface from the leading edge and seven roughness magnitudes(Ra)ranging from 52 to525 lm were *** showed that the surface roughness mainly determined the loss generation process by influencing the structure of the Laminar separation bubble(LSB)and the turbulence level near the *** all the roughness locations,the variation trend for the profile loss with the roughness magnitude was *** the transitionally rough region,the negative displacement effect of the LSB was suppressed with the increase of roughness magnitude,leading to a maximum decrease of 14.6%,16.04%,16.45%and 10.20%in the profile loss at Ra=157 lm for the four roughness locations,***,with a further increase of the roughness magnitude in the fully rough region,the stronger turbulent dissipation enhanced the growth rate of the turbulent boundary layer and increased the profile loss *** comparison,the leading edge roughness played a dominant role in the boundary layer development and performance *** take fully advantage of the surface roughness reducing profile loss at low Re,the effects of roughness on suppressing LSB and inducing strong turbulent dissipation should be balanced effectively.

关键词： Aerodynamic performance Compressor airfoil Low Reynolds number separation bubble Surface roughness Viscous dissipation

Effects of Freestream Turbulence on Bypass Transition of Separated Boundary Layer on Low-Pressure Turbine Airfoils

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Journal of Thermal Science 2012年第3期21卷 230-235页

作者： Hideo Taniguchi Hiroshi Sakai Ken-ichi Funazaki Department of Mechanical Systems Engineering Faculty of EngineeringIwate University

This paper presents experimental studies on bypass transition of separated boundary layer on low-pressure turbine airfoils,focusing on the effects of freestream turbulence on the transition ***-wire probe measurements are performed on the suction side of an airfoil in the low-pressure linear turbine cascade at several Reynolds number *** turbulence is enhanced by use of turbulence grid located upstream of the *** results of this experimental study show that the location of boundary layer separation does not strongly de-pend on the freestream turbulence ***,as the freestream turbulence level increases,the size of separa-tion bubble becomes small and the location of turbulent transition moves *** size of separation bubble becomes small as the Reynolds number *** low freestream turbulence intensity,the velocity fluctuation due to Kelvin-Helmholtz instability is observed clearly in the shear layer of the separation *** high frees-tream turbulence intensity,the streak structures appear upstream of the separation location,indicating bypass transition of attached boundary layer occurs at high Reynolds number.

关键词： Aeroengine Low-Pressure Turbine Bypass Transition separation bubble

Assessment and improvement of k-ω-γ model for separation-induced transition prediction

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Chinese Journal of Aeronautics 2022年第11期35卷 219-234页

作者： Yatian ZHAO Jianqiang CHEN Rui ZHAO Hongkang LIU School of Aeronautics and Astronautics Central South UniversityChangsha 41083China State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China School of Aerospace Engineering Bejing Institute of TechnologyBeijing 100081China Key Laboratory of Traffic Safety on Track of Ministry of Education School of Traffic&Transportation EngineeringCentral South UniversityChangsha 410075China

The purpose of this work is to improve the k-ω-γtransition model for separationinduced transition *** fundamental cause of the excessively small separation bubble predicted by k-ω-γmodel is scrutinized from the perspective of model *** the basis,three rectifications are conducted to improve the k-ω-γmodel for separation-induced ***,a damping function is established via comparing the molecular diffusion timescale with the rapid pressure-strain *** damping function is applied to prevent the effective length scale from incorrect distribution near the leading edge of the separation ***,the pressure gradient parameterλζ,is proposed as an indicator for local susceptibility to the separation ***,λζ,-based separation intermittencyγsep is constructed to accelerate the substantial growth of turbulent kinetic energy after flow *** improved model appropriate for both low-and high-speed flow has been calibrated against a variety of diverse and challenging experiments,including the subsonic T3L plate,Aerospatial A airfoil,transonic NLR-7301 airfoil and deformed hypersonic inflatable aerodynamic decelerator *** improved model is strictly based on local variables and Galilean ***,the proposed improvement for k-ω-γmodel can be fairly convenient to incorporate into other existing intermittency-based transition models.

关键词： Boundary layer transition Intermittency Local variables separation bubble Transition model

Numerical Investigation of Centerline Curvature Effects on a Compact S-shaped Intake

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Journal of Thermal Science 2012年第5期21卷 413-419页

作者： Enliang Huang Shengfeng Zhao Zhijun Lei Jianxiong Kang Xingen Lu Junqiang Zhu Key Laboratory of Light-duty Gas-turbine Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190 China University of Chinese Academy of Sciences Beijing 100190 China

Taking into account stealth, structure and maintenance, ultra-compact S-shaped intake has been widely used in modem vehicles. In this paper a series of steady numerical simulation were carried out to investigate the complex flow mechanism in s-shaped intake, particular attention was given to examining the effect of centerline curvature on the performance and flowfield of an ultra-compact S-shaped intake. In order to validate the multi-block model, the computational results for Royal Aircraft Establishment intake 2129-M2129 which had modest centerline cur- vature distribution were corrected with available experimental test data. The numerical simulation results agreed fairly well with the experimental data, and the computational method was then used to investigate the effects of different centerline curvature distributions on performance and flow field in compact S-shaped intake. Detailed analyses of the flow visualization had exposed the different flow topologies between the cases with different cen- terline curvature. It was found that different centerline curvature distributions changed the initial location and the size of separation bubble, as well as the strength of two counter-rotating vortices at the entrance of engine.

关键词： S-shaped Intake Secondary Flow Centerline Curvature separation bubble Counter-rotating Vortices

Active control of noise amplification in the flow over a square leading-edge flat plate utilizing DBD plasma actuator

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Plasma Science and Technology 2018年第5期20卷 157-161页

作者： Yadong HUANG Benmou ZHOU Science and Technology on Transient Physics Laboratory Nanjing University of Science and TechnologyNanjing 210094People＇s Republic of China

Perturbation is generally considered as the flow noise,and its energy can gain transient growth in the separation *** amplified perturbations may cause unstable Kelvin–Helmohltz vortices which induce the three-dimensional *** control of noise amplification via dielectric barrier discharge plasma actuator in the flow over a square leading-edge flat plate is numerically *** actuator is installed near the plate leading-edge where the separation bubble is *** maximum energy amplification of perturbations is positively correlated with the separation bubble scale which decreases with the increasing control *** the magnitude of noise amplification is reduced,the laminar-turbulent transition is successfully suppressed.

关键词： separation bubble noise amplification DBD plasma actuator transition suppression

Vortex dynamics and entropy generation in separated transitional flow over a compressor blade at various incidence angles

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Chinese Journal of Aeronautics 2022年第3期35卷 42-52页

作者： Mingyang WANG Ziliang LI Ge HAN Chengwu YANG Shengfeng ZHAO Yanfeng ZHANG Xin’gen LU Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The transition process within a Laminar separation bubble(LSB)that formed on a compressor blade surface was investigated using Large Eddy Simulations(LESs)at a Reynolds number of 1.5×10;and incidence angles of 0°,+3°,and+5°.The vortex dynamics in the separated shear layers were compared at various incidence angles and its effects on the loss generation were clarified through entropy *** showed that transition onset,which was accurately identified by the Linear Stability Theory(LST),was significantly promoted at the increased incidence *** such,the development of LSB was suppressed and the relative role of viscous instability played in the transition process was *** the incidence angle of 0°,two-dimensional spanwise vortices detached from the blade surface and roiled up periodically,which were further stretched and eventually evolved into large-scale hairpin *** time passed,the fully developed hairpin vortices broke down into small-scale ***,the flow near the wall reversely ejected into the outer separated shear layers and a sweeping process happened subsequently,forcing the separated shear layers to reattach and accelerating the generation of turbulent *** comparison,the strength of vortex rolling-up was weakened at higher incidence angles,and the vortex pairing and breakdown of large-scale vortices were less ***,the level of turbulent fluctuations that generated in the separated shear layers was *** entropy analysis showed that the turbulent dissipation effect related to the Reynolds shear stresses determined the largest amount of positive entropy generation,which declined to a lower level as the incidence angle increased from 0°to+5°.Correspondingly,the profile loss was reduced by 50.4%.

关键词： Aerodynamic performance Compressor airfoil Entropy Incidence angle separation bubble Vortex dynamics

Survey of control techniques to alleviate repercussions of shock-wave and boundary-layer interactions

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Advances in Aerodynamics 2022年第1期4卷 569-598页

作者： Tamal Jana Mrinal Kaushik Department of Aerospace Engineering JAIN(Deemed-to-be University)Bangalore560069India Department of Aerospace Engineering Indian Institute of Technology KharagpurKharagpur721302India

The primary focus of the present survey is to categorize the results of various investigations on the Shock/Boundary-Layer Interactions(SBLIs),their repercussions,and the effective ways to control *** interactions of shock waves with the boundary layer are an important area of research due to their ubiquity in several applications ranging from transonic to hypersonic ***,there is a need for a detailed inspection to understand the phenomena to predict its characteristics with certain *** this in mind,this article presents some key features of the physical nature of SBLIs,their consequences,and the control techniques in a sequential manner;in particular,the passive control techniques for the supersonic and hypersonic intakes are reviewed in detail.

关键词： Oblique shock Boundary layer separation bubble Surface bump Porous cavity Micro-vortex generator(MVG) Plasma jet

Numerical Prediction of Fluid Flow and Heat Transfer in a Wavy Pipe

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Journal of Thermal Science 2001年第2期10卷 133-138,147页

作者： Shohel Mahmud A.K.M. Sadrul Islam Prodip Kumar Das Department of Mechanical Engineering, Bangladesh University of Engineering & Technology, BUET, Dhaka-1000, Bangladesh Department of Mechanical Engineering Bangladesh University of Engineering & Technology BUET Dhaka Bangladesh

Hydrodynamic and thermal characteristics in a pipe with sinusoidal wavy surface for steady laminar flow are invdtigted numerically in the present study. The integral forms of governing equations are discretized using control volume based Finite Volume method with collocated variable arrangement, SIMPLE algorithm is used and TDMA solver is applied for solution of system of equations. A pipe of length equal to 4λ is considered. Effect of surface waviness, determined by wavelength-amplitude ratio λ/a (=L), on flow and thermal field is presented. The simulation work has been carried out for L’=11.0 -30.0 for a Reynolds number range50 to 2000. Results are presented in the form of Streamfunction, isothermal lines, velocity and vorticity profiles, change of mean friction factor, variation in skin fiction. local and average Nusselt number with Reynolds number, wave number (n) and L’. For a particular geometry. length of circulation zone increases with Reynolds number and approaches a limiting value for higher Reynolds number. Wall shear stress in the bulge part of the chancel shows smaller values that affect largely the be of heat transfer and Nusselt number shows minimum values in this region. This circulation zone drastically increases with the increase of surface waviness showing high mean friction factor per wavelength. Mean friction factor inversely varies with Reynolds number. A correlation is proposed for calculating friction factor in the form f=C/(Re)m, where ’C and ’m’ represents two polynomials of degree 4 and 2 respectively and are function of L. Higher waviness of the surface shows the higher heat transfer rate than lower waviness. Heat transfer rate falls almost exponentially along the axial direction with the increase of wave number.

关键词： Nusselt number separation bubble surface wavomess wall vorticity

Numerical Study on Low-Reynolds Compressible Flows around Mars Helicopter Rotor Blade Airfoil

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Journal of Flow Control, Measurement & Visualization 2023年第2期11卷 30-48页

作者： Takuma Yamaguchi Masayuki Anyoji Interdisciplinary Graduate School of Engineering Sciences Kyushu University Fukuoka Japan

High-speed rotor rotation under the low-density condition creates a special low-Reynolds compressible flow around the rotor blade airfoil where the compressibility effect on the laminar separated shear layer occurs. However, the compressibility effect and shock wave generation associated with the increase in the Mach number (M) and the trend change due to their interference have not been clarified. The purpose is to clear the compressibility effect and its impact of shock wave generation on the flow field and aerodynamics. Therefore, we perform a two-dimensional unsteady calculation by Computational fluid dynamics (CFD) analysis using the CLF5605 airfoil used in the Mars helicopter Ingenuity, which succeeded in its first flight on Mars. The calculation conditions are set to the Reynolds number (Re) at 75% rotor span in hovering (Re = 15,400), and the Mach number was varied from incompressible (M = 0.2) to transonic (M = 1.2). The compressible fluid dynamics solver FaSTAR developed by the Japan aerospace exploration agency (JAXA) is used, and calculations are performed under multiple conditions in which the Mach number and angle of attack (α) are swept. The results show that a flow field is similar to that in the Earth’s atmosphere above M = 1.0, such as bow shock at the leading edge, whereas multiple λ-type shock waves are observed over the separated shear layer above α = 3° at M = 0.80. However, no significant difference is found in the Cp distribution around the airfoil between M = 0.6 and M = 0.8. From the results, it is found that multiple λ-type shock waves have no significant effect on the airfoil surface pressure distribution, the separated shear layer effect is dominant in the surface pressure change and aerodynamic characteristics.

关键词： CFD CLF5605 Rotor Blade Airfoil Compressibility Effect Low-Reynolds Number Mars Helicopter separation bubble Shock Wave