A Modulation Technique for Measuring Small Disturbances in the Upstream Flow Field of a Sharp Leading Edge in a Rarefied Hypersonic Flow

1973 ◽  
pp. 547-556
Author(s):  
Fernand De Geyter
Keyword(s):  
Flow Field ◽  
Hypersonic Flow ◽  
Leading Edge ◽  
Modulation Technique ◽  
Upstream Flow ◽  
Sharp Leading Edge ◽  
Small Disturbances

Experimental Investigation of Steady and Unsteady Flow Field Downstream of an Automotive Torque Converter Turbine and Inside the Stator: Part II—Unsteady Pressure on the Stator Blade Surface

1997 ◽  
Vol 119 (3) ◽  
pp. 634-645 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
D. G. Maddock
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Torque Converter ◽  
Fast Response ◽  
Ensemble Averaging ◽  
Pressure Transducers ◽  
Stator Blade ◽  
Response Pressure ◽  
Aperiodic Component ◽  
Upstream Flow

The stator flow field of an automotive torque converter is highly unsteady due to potential and viscous interactions with upstream and downstream rotors. The objective of this investigation is to understand the influence of potential and viscous interactions of the upstream rotor on the stator surface pressure field with a view toward improvement of the stator design. Five miniature fast-response pressure transducers were embedded on the stator blade. The measurements were conducted at three locations near the leading edge and two locations near the trailing edge at the midspan location. The upstream flow field was measured using a fast response five-hole probe and is described in Part I of this paper. The experimental data were processed in the frequency domain by spectrum analysis and in the temporal-spatial domain by the ensemble-averaging technique. The flow properties were resolved into mean, periodic, aperiodic, and unresolved components. The unsteady amplitudes agreed well with the pressure envelope predicted by panel methods. The aperiodic component was found to be significant due to the rotor–rotor and rotor–stator interactions observed in multistage, multispool environment.

scholarly journals Experimental Investigation of Steady and Unsteady Flow Field Downstream of an Automotive Torque Converter Turbine and Inside the Stator: Part II — Unsteady Pressure on the Stator Blade Surface

1995 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Donald G. Maddock
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Torque Converter ◽  
Fast Response ◽  
Ensemble Averaging ◽  
Pressure Transducers ◽  
Stator Blade ◽  
Response Pressure ◽  
Aperiodic Component ◽  
Upstream Flow

The stator flow field of an automotive torque converter is highly unsteady due to potential and viscous interactions with upstream and downstream rotors. The objective of this investigation is to understand the influence of potential and viscous interactions of the upstream rotor on the stator surface pressure field with a view towards improvement of the stator design. Five miniature fast-response pressure transducers were embedded on the stator blade. The measurements were conducted at three locations near the leading edge and two locations near the trailing edge at the mid-span location. Upstream flow field was measured using a fast response five-hole probe and is described in the first part of this paper. The experimental data were processed in the frequency domain by spectrum analysis and in temporal-spatial domain by the ensemble averaging technique. The flow properties were resolved into mean, periodic, aperiodic and unresolved components. The unsteady amplitudes agreed well with the pressure envelope predicted by panel methods. Aperiodic component was found to be significant due to the rotor-rotor and rotor-stator interactions observed in multistage, multi-spool environment.

Heat alleviation studies on hypersonic re-entry vehicles

2018 ◽  
Vol 122 (1257) ◽  
pp. 1673-1696 ◽  
Author(s):  
M. Khalid ◽  
K. A. Juhany
Keyword(s):  
Numerical Simulation ◽  
Boundary Condition ◽  
Flow Field ◽  
Hypersonic Flow ◽  
Flow Rate ◽  
Leading Edge ◽  
Control Surface ◽  
Solid Boundary ◽  
Simulation Techniques ◽  
Hypersonic Speeds

ABSTRACTA numerical simulation has been carried out to investigate the effects of leading edge blowing upon heat alleviation on the surface of hypersonic vehicles. The initial phase of this work deals with the ability of the present CFD-based techniques to solve hypersonic flow field past blunt-nosed vehicles at hypersonic speeds. Towards this end, the authors selected three re-entry vehicles with published flow field data against which the present computed results could be measured. With increasing confidence on the numerical simulation techniques to accurately resolve the hypersonic flow, the boundary condition at the solid blunt surface was then equipped with the ability to blow the flow out of the solid boundary at a rate of at least 0.01–0.1 times the free stream (ρ∞u∞) mass flow rate. The numerical iterative procedure was then progressed until the flow at the surface matched this new ‘inviscid like’ boundary condition. The actual matching of the flow field at the ejection control surface was achieved by iterating the flow on the adjacent cells until the flow conformed to the conditions prescribed at the control surface. The conditions at the surface could be submitted as a ρ∞u∞at the surface or could be equipped as a simple static pressure condition providing the desired flow rate. The comparison between the present engineering approach and the experimental data presented in this study demonstrate its ability to solve complex problems in hypersonic.

INFLUENCE OF THE PLATE LEADING-EDGE SHAPE AND THICKNESS ON THE BOUNDARY LAYER LAMINAR-TURBULENT TRANSITION IN HYPERSONIC FLOW

2019 ◽  
Vol 50 (5) ◽  
pp. 461-481
Author(s):  
Sergei Vasilyevich Aleksandrov ◽  
Evgeniya Andreevna Aleksandrova ◽  
Volf Ya. Borovoy ◽  
Andrey Vyacheslavovich Gubernatenko ◽  
Vladimir Evguenyevich Mosharov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Hypersonic Flow ◽  
Leading Edge ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

Numerical simulation of swirling flow effect on the first stage vane film cooling distribution

2016 ◽  
Vol 07 (03) ◽  
pp. 1650031
Author(s):  
Hong Yin
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Swirling Flow ◽  
Cooling System ◽  
Leading Edge ◽  
Suction Side ◽  
Local Area ◽  
Swirl Flow ◽  
Flow Effect ◽  
Recirculation Flow

In advanced gas turbine technology, lean premixed combustion is an effective strategy to reduce peak temperature and thus, NO[Formula: see text] emissions. The swirler is adopted to establish recirculation flow zone, enhancing mixing and stabilizing the flame. Therefore, the swirling flow is dominant in the combustor flow field and has impact on the vane. This paper mainly investigates the swirling flow effect on the turbine first stage vane cooling system by conducting a group of numerical simulations. Firstly, the numerical methods of turbulence modeling using RANS and LES are compared. The computational model of one single swirl flow field is considered. Both the RANS and LES results give reasonable recirculation zone shape. When comparing the velocity distribution, the RANS results generally match the experimental data but fail to at some local area. The LES modeling gives better results and more detailed unsteady flow field. In the second step, the RANS modeling is incorporated to investigate the vane film cooling performance under the swirling inflow boundary condition. According to the numerical results, the leading edge film cooling is largely altered by the swirling flow, especially for the swirl core-leading edge aligned case. Compared to the pressure side, the suction side film cooling is more sensitive to the swirling flow. Locally, the film cooling jet is lifted and turned by the strong swirling flow.

Numerical Investigation of Intermittent Corner Separation in a Linear Compressor Cascade

2016 ◽  
Author(s):  
Wei Ma ◽  
Feng Gao ◽  
Xavier Ottavy ◽  
Lipeng Lu ◽  
A. J. Wang
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Leading Edge ◽  
Suction Side ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Linear Compressor ◽  
Corner Separation ◽  
Eddy Simulation ◽  
Linear Compressor Cascade

Recently bimodal phenomenon in corner separation has been found by Ma et al. (Experiments in Fluids, 2013, doi:10.1007/s00348-013-1546-y). Through detailed and accurate experimental results of the velocity flow field in a linear compressor cascade, they discovered two aperiodic modes exist in the corner separation of the compressor cascade. This phenomenon reflects the flow in corner separation is high intermittent, and large-scale coherent structures corresponding to two modes exist in the flow field of corner separation. However the generation mechanism of the bimodal phenomenon in corner separation is still unclear and thus needs to be studied further. In order to obtain instantaneous flow field with different unsteadiness and thus to analyse the mechanisms of bimodal phenomenon in corner separation, in this paper detached-eddy simulation (DES) is used to simulate the flow field in the linear compressor cascade where bimodal phenomenon has been found in previous experiment. DES in this paper successfully captures the bimodal phenomenon in the linear compressor cascade found in experiment, including the locations of bimodal points and the development of bimodal points along a line that normal to the blade suction side. We infer that the bimodal phenomenon in the corner separation is induced by the strong interaction between the following two facts. The first is the unsteady upstream flow nearby the leading edge whose angle and magnitude fluctuate simultaneously and significantly. The second is the high unsteady separation in the corner region.

scholarly journals Aerothermal Investigations of Mixing Flow Phenomena in Case of Radially Inclined Ejection Holes at the Leading Edge

1999 ◽  
Author(s):  
Dieter E. Bohn ◽  
Karsten A. Kusterer
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Leading Edge ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Fluid ◽  
Flow Phenomena ◽  
Vortex Systems

A leading edge cooling configuration is investigated numerically by application of a 3-D conjugate fluid flow and heat transfer solver, CHT-Flow. The code has been developed at the Institute of Steam and Gas Turbines, Aachen University of Technology. It works on the basis of an implicit finite volume method combined with a multi-block technique. The cooling configuration is an axial turbine blade cascade with leading edge ejection through two rows of cooling holes. The rows are located in the vicinity of the stagnation line, one row is on the suction side, the other row is on the pressure side. The cooling holes have a radial ejection angle of 45°. This configuration has been investigated experimentally by other authors and the results have been documented as a test case for numerical calculations of ejection flow phenomena. The numerical domain includes the internal cooling fluid supply, the radially inclined holes and the complete external flow field of the turbine vane in a high resolution grid. Periodic boundary conditions have been used in the radial direction. Thus, end wall effects have been excluded. The numerical investigations focus on the aerothermal mixing process in the cooling jets and the impact on the temperature distribution on the blade surface. The radial ejection angles lead to a fully three dimensional and asymmetric jet flow field. Within a secondary flow analysis it can be shown that complex vortex systems are formed in the ejection holes and in the cooling fluid jets. The secondary flow fields include asymmetric kidney vortex systems with one dominating vortex on the back side of the jets. The numerical and experimental data show a good agreement concerning the vortex development. The phenomena on the suction side and the pressure side are principally the same. It can be found that the jets are barely touching the blade surface as the dominating vortex transports hot gas under the jets. Thus, the cooling efficiency is reduced.

scholarly journals Smooth leading edge transition in hypersonic flow

1999 ◽  
Vol 26 (1-2) ◽  
pp. 169-176 ◽  
Author(s):  
L. Gaillard ◽  
E. Benard ◽  
T. Alziary de Roquefort
Keyword(s):  
Hypersonic Flow ◽  
Leading Edge
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