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AIAA JOURNAL 2012年第4期50卷 985-988页

作者： Chung, Kung-Ming Chang, Po-Hsiung Chang, Keh-Chin Natl Cheng Kung Univ Aerosp Sci & Technol Res Ctr Tainan 701 Taiwan Natl Cheng Kung Univ Inst Aeronaut & Astronaut Tainan 701 Taiwan

The article offers information on supersonic convex-corner flows. It is said that an interaction law can be developed in an explicit form that would relate the displacement effect of the boundary layer to the pressure. The pressure is induced in the inviscid pan of subsonic flows. Studies that attributed the flow properties near the corner to the viscous-inviscid interaction are scarce.

关键词： Boundary Layer Separation Freestream Mach Number flow visualization techniques Static Pressure Standard Deviation Compressible flow Supersonic Speed Transonic Wind Tunnel Pressure Transducers flow Characteristics

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MULTISPARK flow visualization OF LATERAL JET INJECTION INTO A SWIRLING CROSS flow

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JOURNAL OF PROPULSION AND POWER 1985年第6期1卷 485-487页

作者： FERRELL, GB AOKI, K LILLEY, DG OKLAHOMA STATE UNIV SCH MECH & AEROSP ENGNSTILLWATEROK 74078 TOKAI UNIV DEPT MECH ENGNHIRATSUKAKANAGAWA 25912JAPAN

Multispark flow visualization experiments have been conducted to characterize the time-mean flowfield of a deflected turbulent jet in a confining cylindrical cross flow. Jet/cross-flow velocity ratios of 2, 4, and 6 were investigated, under cross-flow inlet swirler vane angles of 0 (swirler removed), 45, and 70 deg. The flow visualization results highlight interesting features of the flowfield, as well as the trajectory and spread pattern of the deflected jet. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： flow visualization techniques Combustor Design Turbulence Models Neutral Buoyancy Turbulent flow Gas Turbine Transformer Ramjet Vortices

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A NEW APPROACH TO flow PROBLEMS PAST A POROUS PLATE

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AIAA JOURNAL 1985年第12期23卷 1916-1921页

作者： INOUE, O Institute of Space and Astronautical Science Tokyo Japan

A new method to simulate flows past a two-dimensional porous plate is proposed. The method is a simple application of a discrete vortex method that has been well established for flows past an inclined flat plate. In this method, a flow past a porous plate is described as superposition of the velocity potential of a uniform flow on that of a flow past a flat plate. The effect of porosity is replaced by that of a mass flow rate of the approaching freestream passing through the plate. Calculated flow features are compared with experiments. It is shown that the present method is effective in the simulation of the flow past a porous plate. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Karman Vortex Street Accelerating flow Mass flow Rate Freestream Velocity Angle of Attack flow visualization techniques Shear Layers Symmetric Airfoil Jet Engine Inlet flow Mathematical Models

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flow visualization STUDY OF TIP LEAKAGE flowS ACROSS CANTILEVERED STATOR-BLADES

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JOURNAL OF PROPULSION AND POWER 1988年第2期4卷 144-151页

作者： ADAMS, NG HEPWORTH, HK NO ARIZONA UNIV DEPT MECH ENGN & TECHNOLFLAGSTAFFAZ 86011

A test program has been conducted to study tip leakage flows associated with cantilevered stator blades in axial flow compressor systems. A low-speed single-stage test rig has been developed to simulate flows characteristically found in middle-stage axial flow compressors. The test rig is designed specifically to accommodate flow visualization techniques in the study of cantilever stator blade tip leakage flows. Extensive testing demonstrates that the test rig simulates axial compressor stage performance characteristics. Data taken include both on- and off-design operating conditions. Data reduction and analysis of high-speed film footage provides actual tip leakage path lines and velocities for four different tip treatments. The tip treatments investigated are baseline (no tip treatment), pumping groove, double winglet, and pressure side winglet. Of the four tip treatments tested, the pumping groove proved to be the most effective in reducing tip leakage. © 1987 American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： flow visualization techniques Axial flow Compressor Winglets Cantilever Data Reduction Static Pressure Blade Loading flow Conditions Aspect Ratio flow Characteristics

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Supersonic Cavity flow Control Using a Spanwise Array of Leading-Edge Tabs

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JOURNAL OF AIRCRAFT 2022年第3期59卷 788-798页

作者： Singh, Surabhi Ukeiley, Lawrence Zhang, Yang Cattafesta, Louis Taira, Kunihiko Univ Florida Dept Mech & Aerosp Engn Gainesville FL 32611 USA Florida State Univ Florida Ctr Adv Aeropropuls Dept Mech Engn Tallahassee FL 32310 USA Univ Calif Los Angeles Dept Mech & Aerosp Engn Los Angeles CA 90095 USA

Motivated by the successful application of active control using segmented spanwise blowing, this work investigates passive flow control for a rectangular cavity in supersonic flow using a spanwise array of leading-edge tabs to reduce unsteady pressure loads on the cavity surface. The cavity studied here has a length-to-depth ratio of 6 and width-to-depth ratio of 6 with a turbulent boundary layer at the leading edge and a freestream Mach number of 1.4. Fluctuating surface pressure measurements within the cavity show that the leading-edge tabs have similar effectiveness as leading-edge blowing of the same spanwise wavelength in reducing pressure fluctuations on the cavity surfaces. Streamwise-aligned particle image velocimetry (PIV) measurements show evidence of deflection of the shear layer at the cavity opening and modification of recirculation characteristics associated with the controlled flow. Furthermore, cross-stream stereoscopic PIV measurements reveal counter-rotating streamwise vortices, which persist throughout the cavity length. Proper orthogonal decomposition modes of cross-stream-aligned PIV measurements show that leading-edge tabs are successful in breaking up the flow into smaller-scale modes. Surface flow visualization of the cavity floor and aft wall show differences in the recirculation patterns for the baseline and controlled flows. The present analysis provides insights on how the passive tabs effectively control high-speed cavity flow and demonstrates that the control mechanisms are analogous to steady leading-edge blowing strategies.

关键词： Leading Edges Turbulent Boundary Layer Particle Image Velocimetry Freestream Mach Number Horseshoe Vortex flow Conditions flow visualization techniques Passive Control Supersonic Wind Tunnels Power Spectral Density

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CROSS-flow VORTEX AND TRANSITION MEASUREMENTS BY USE OF MULTIELEMENT HOT FILMS

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AIAA JOURNAL 1992年第9期30卷 2212-2218页

作者： AGARWAL, NK MADDALON, DV MANGALAM, SM COLLIER, FS NASA LANGLEY RES CTRLAMINAR FLOW CONTROL PROJECT OFFHAMPTONVA 23665

An experiment on a 45-deg swept wing was conducted to study three-dimensional boundary-layer characteristics using surface-mounted, microthin, multielement hot-film sensors. A large hot-film gauge was fabricated that combined three arrays of 64 crossflow sensors each and a single array of 32 transition sensors. Two such gauges were mounted along the model chord. Crossflow vortex structure and boundary-layer transition were measured from the simultaneously acquired signals of the hot films. Stationary and nonstationary crossflow disturbances were measured from hot-film sensor arrays. Spanwise variation of the root-mean-square hot-film signal show a local minima and maxims. The distance between two minima corresponds to the stationary crossflow vortex wavelength and agrees with naphthalene flow-visualization results. The chordwise and span-wise variation of amplified traveling (nonstationary) crossflow disturbance characteristics were measured as Reynolds number was varied. The frequency of the most amplified crossflow disturbances agrees with linear stability theory.

关键词： Vortex Structure Sensors flow visualization techniques Freestream Velocity Aircraft Wings Three Dimensional Boundary Layer Transitional flow Wind Tunnel Models Data Acquisition Analog to Digital Converters

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INVESTIGATION OF SUPERSONIC-flow ABOUT STRUT ENDWALL INTERSECTIONS IN AN ANNULAR DUCT

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AIAA JOURNAL 1995年第4期33卷 586-594页

作者： WILLIAMS, KE HARLOFF, GJ GESSNER, FB SVERDRUP TECHNOL INC BROOKPARKOH 44142

A combined experimental and numerical study was conducted to investigate the nature of supersonic turbulent dow past an array of four, circumferentially equidistant, diamond-shaped struts which spanned the width of an annular, constant area duct. The validity of the experimental and numerical techniques is demonstrated by comparing predicted and measured duet wall static pressure, pitot pressure, and limiting surface streamlines. The computations and experiments both indicate a complex shock structure which persists many chord lengths downstream of the strut. The computations and experiments also reveal the existence of horseshoe-type vortices which are generated at the leading and trailing edges of the struts. Corner vortices are generated at the intersections of both the compression and expansion faces of the struts with the duct walls.

关键词： flow Conditions Strakes Horseshoe Vortex Trailing Edges Static Pressure Surface Streamlines Aerodynamics flow visualization techniques Baldwin Lomax Turbulence Model Boundary Layer Thickness

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INVESTIGATION OF THE INTERACTING flow OF NONSYMMETRIC JETS IN CROSS-flow

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AIAA JOURNAL 1988年第8期26卷 940-947页

作者： WU, JM VAKILI, AD YU, FM University of Tennessee Space Institute Tullahoma Tennessee

Asymmetric jets in crossflow provide complex interacting flowfields that contain many vortices. These vortices change significantly with variations of the jet and the crossflow and under certain specific conditions in which shedding vortices appear and disappear periodically. Four different cross-section geometry jets were studied and compared with a circular cross-section jet, all with the same jet exit area. Various flow visualization techniques were used to aid in understanding the highly complex three-dimensional flowfield. Among many forms of secondary vortices observed, in general, four major vortices were identified. The most notable and interesting group was the “spin-off” vortices observed previously in our study of discrete jets blowing from a wing tip. These shedding vortices were formed under certain flow conditions and jet orientations. The shedding vortices were nearly parallel to the jet exit axis, with periodicity depending on the jet/freestream velocity ratio. A schematic reconstruction was made of the asymmetric flowfield based on observations of the flow evolution, and relationships with symmetric jets in crossflow were established. Unsteady jets created by pulsation of the jet flow at low pulsation frequencies were observed to behave quite differently from the steady jets and penetrated farther into the crossflow. © 1988 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Horseshoe Vortex flow Conditions flow visualization techniques Wing Tip Freestream Velocity Yaw Laminar Boundary Layer Jet Stream Histograms Analog to Digital Converters

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Active flow Control in Compressor Cascades with Steady and Pulsed Jets

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JOURNAL OF PROPULSION AND POWER 2023年第4期39卷 501-510页

作者： Chen, Shaowen Yang, Pengcheng Shi, Yuchen Meng, Qinghe Harbin Inst Technol Sch Energy Sci & Engn Harbin 150001 Peoples R China

This paper describes a detailed experimental investigation into the impact of steady and pulsed blowing on endwall secondary structures and losses in a compressor cascade. Owing to their high configuration flexibility, injection holes are integrated in the cascade sidewalls to manage the secondary flows. Loss reductions of 3.2 and 5.72% relative to the uncontrolled case are achieved by steady blowing with straight and optimized inclined holes, respectively. Superior loss reduction of 7.85% is obtained by pulsed blowing through inclined holes. To identify the secondary flow structures near the endwall and suction surfaces, a self-developed oil visualization method and spatial-spectral analysis are performed. Experimental results show that two concentrated shedding vortices exist in the cascade corner region. Loss reduction is achieved as the blowing suppresses the dominant vortex. Pulsed blowing intensifies the acceleration effect on the boundary layer, resulting in better performance with the same injection velocity. The impact of the pulse frequency on loss generation is investigated, and it is found that the optimal frequency is close to the shedding frequency of the dominant vortex in the cascade corner region.

关键词： Active flow Control Horseshoe Vortex flow visualization techniques Oil visualizations Spatial-Spectral Analysis Compressor Cascade Steady and Pulsed Blowing Low-Speed Wind Tunnel

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SIMPLE METHOD OF SUPERSONIC-flow visualization USING SMOKE

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AIAA JOURNAL 1992年第1期30卷 278-279页

作者： MILLER, LS IRANI, E Wichita State University Wichita Kansas 67208

Direct smoke injection is a common and popular means for studying aerodynamic phenomena in wind tunnels. A modified smoke wire visualization method for application in high-speed and supersonic flows ahs been devloped which produces a large number of fine smoke filaments that do not dissipate. The principal difference between this technique and the low-Reynolds-number method is related to the diameter and placement of the smoke-generation wire. tech

关键词： flow visualization techniques Supersonic Wind Tunnels Angle of Attack Aerospace Engineering Supersonic flow Supersonic Speed Thermal Expansion Detached Shock Oblique Shock

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