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NATURE OF THE SURFACE HEAT TRANSFER FLUCTUATION IN A HYPERSONIC SEPARATED TURBULENT FLOW
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作者 Wang Shifen Li Qingquan (Institute of Mechanics,Chinese Academy of Sciences) 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1990年第4期296-302,共7页
This paper presents the results of an experimental study of the unsteady nature of a hypersonic sepa- rated turbulent flow.The nominal test conditions were a freestream Mach number of 7.8 and a unit Reynolds number of... This paper presents the results of an experimental study of the unsteady nature of a hypersonic sepa- rated turbulent flow.The nominal test conditions were a freestream Mach number of 7.8 and a unit Reynolds number of 3.5x10^7/m.The separated flow was generated using finite span forward facing steps.An array of flush mounted high spatial resolution and fast response platinum film resistance thermometers was used to make mul- ti-channel measurements of the fluctuating surface heat trtansfer within the separated flow.Conditional sampling ana- lysis of the signals shows that the root of separation shock wave consists of a series of compression wave extending over a streamwise length about one half of the incoming boundary layer thickness.The compression waves con- verge into a single leading shock beyond the boundary layer.The shock structure is unsteady and undergoes large-scale motion in the streamwise direction.The length scale of the motion is about 22 percent of the upstream influence length of the separation shock wave.There exists a wide band of frequency of oscillations of the shock system.Most of the frequencies are in the range of 1-3 kHz.The heat transfer fluctuates intermittently between the undisturbed level and the disturbed level within the range of motion of the separation shock wave.This inter mittent phenomenon is considered as the consequence of the large-scale shock system oscillations.Downstream of the range of shock wave motion there is a separated region where the flow experiences continuous compression and no intermittency phenomenon is observed. 展开更多
关键词 hypersonic separated turbulent flow shock wave and turbulent boundary layer interaction heat transfer fluctuation unsteady shock structure
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Numerical simulation of the pulsing air separation field based on CFD 被引量:12
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作者 He Jingfeng He Yaqun +2 位作者 Zhao Yuemin Duan Chenlong Ye Cuiling 《International Journal of Mining Science and Technology》 2012年第2期201-207,共7页
The flow field of pulsing air separation is normally in an unsteady turbulence state.With the application of the basic principles of multiphase turbulent flows,we established the dynamical computational model,which sh... The flow field of pulsing air separation is normally in an unsteady turbulence state.With the application of the basic principles of multiphase turbulent flows,we established the dynamical computational model,which shows a remarkable variation of the unstable pulsing air flow field.CFD(computational fluid dynamics) was used to conduct the numerical simulation of the actual geometric model of the classifier.The inside velocity of the flowing fields was analyzed later.The simulation results indicate that the designed structure of the active pulsing air classifier provided a favorable environment for the separation of the particles with different physical characters by density.We shot the movement behaviors of the typical tracer grains in the active pulsing flow field using a high speed dynamic camera.The displacement and velocity curves of the particles in the continuous impulse periods were then analyzed.The experimental results indicate that the effective separation by density of the particles with the same settling velocity and different ranges of the density and particle size can be achieved in the active pulsing airflow field.The experimental results provide an agreement with the simulation results. 展开更多
关键词 Pulsing air separation flow fieldMultiphase turbulence flowNumerical simulationHigh-speed dynamic camera imaging
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