› › Experimental Study Of Separated Ramp Induced Shock Boundary Layer Interaction With Upstream Micro Vortex Generation At Mach 2 5

Experimental Study of Separated Ramp-induced Shock/boundary-layer Interaction with Upstream Micro-vortex Generation at Mach 2.5

Author : Yusi Shih

Publisher :

Page : 134 pages

File Size : 10,66 MB

Release : 2014

Category : Boundary layer

ISBN :

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Book Description

Shock wave/boundary layer interactions (SBLIs) are important issues for high-speed vehicles. SBLIs reduce the performance of aerodynamic surfaces and engine inlets, amongst a number of adverse effects. Micro-vortex generators (MVGs) are a flow control method with strong potential to mitigate the effects of SBLI by energizing the boundary layer through momentum transfers from the freestream. They have been implemented in actual configurations at low speeds. The present research includes a combined experimental and theoretical analysis of the evolution of the perturbation downstream the MVG, the formation of vortices, and their interaction with the shock front. Experiments were performed with a baseline MVG configuration of 90° trailing edge on flat plate, ramp alone, and also with MVG mounted ahead of a 20° ramp. The surface flow visualization and particle image velocimetry (PIV) results are presented; the surface flow visualization shows a substantial suppression of SBLIs. A new method to quantify the effectiveness of the MVG on the shock recompression is presented. Moreover, the PIV results were used as the initial input values for the simulation work. A theoretical analysis of the interaction of the MVG perturbation with the boundary layer is performed by assuming linear dynamics of the perturbation. The major assumption is that the interaction between MVG perturbation and the shear flow is affected by transient growth as a result of the non-orthogonality of the linearized Navier-Stokes equations. A new method to perform the projection of the measured perturbation on the continuous modes of the boundary layer is presented. The method takes advantage of the biorthogonality of the direct and adjoint modes. The implementation of such a method using both the Chebyshev polynomials and a shooting algorithm is discussed. The results of the theoretical analysis are encouraging and display a similar trend as the experiments. Both experimental and theoretical results yield perturbation decay not far downstream from the MVG: about 72 mm for experiments, and about 95 mm for simulation. The experiments display two distinguishable growths downstream of MVG, while the simulation predicted one small growth at the very beginning. Both works show trends that agree well with each other.



Shock Wave-Boundary-Layer Interactions

Author : Holger Babinsky

Publisher : Cambridge University Press

Page : 481 pages

File Size : 44,69 MB

Release : 2011-09-12

Category : Technology & Engineering

ISBN : 1139498649

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Book Description

Shock wave-boundary-layer interaction (SBLI) is a fundamental phenomenon in gas dynamics that is observed in many practical situations, ranging from transonic aircraft wings to hypersonic vehicles and engines. SBLIs have the potential to pose serious problems in a flowfield; hence they often prove to be a critical - or even design limiting - issue for many aerospace applications. This is the first book devoted solely to a comprehensive, state-of-the-art explanation of this phenomenon. It includes a description of the basic fluid mechanics of SBLIs plus contributions from leading international experts who share their insight into their physics and the impact they have in practical flow situations. This book is for practitioners and graduate students in aerodynamics who wish to familiarize themselves with all aspects of SBLI flows. It is a valuable resource for specialists because it compiles experimental, computational and theoretical knowledge in one place.



Transition Location Effect on Shock Wave Boundary Layer Interaction

Author : Piotr Doerffer

Publisher : Springer Nature

Page : 540 pages

File Size : 34,35 MB

Release : 2020-07-30

Category : Technology & Engineering

ISBN : 3030474615

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Book Description

This book presents experimental and numerical findings on reducing shock-induced separation by applying transition upstream the shock wave. The purpose is to find out how close to the shock wave the transition should be located in order to obtain favorable turbulent boundary layer interaction. The book shares findings obtained using advanced flow measurement methods and concerning e.g. the transition location, boundary layer characteristics, and the detection of shock wave configurations. It includes a number of experimental case studies and CFD simulations that offer valuable insights into the flow structure. It covers RANS/URANS methods for the experimental test section design, as well as more advanced techniques, such as LES, hybrid methods and DNS for studying the transition and shock wave interaction in detail. The experimental and numerical investigations presented here were conducted by sixteen different partners in the context of the TFAST Project. The general focus is on determining if and how it is possible to improve flow performance in comparison to laminar interaction. The book mainly addresses academics and professionals whose work involves the aerodynamics of internal and external flows, as well as experimentalists working with compressible flows. It will also be of benefit for CFD developers and users, and for students of aviation and propulsion systems alike.



Unsteady Effects of Shock Wave induced Separation

Author : Piotr Doerffer

Publisher : Springer Science & Business Media

Page : 350 pages

File Size : 34,66 MB

Release : 2010-11-25

Category : Technology & Engineering

ISBN : 3642030041

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Book Description

This volume contains description of experimental and numerical results obtained in the UFAST project. The goal of the project was to generate experiment data bank providing unsteady characteristics of the shock boundary layer interaction. The experiments concerned basic-reference cases and the cases with application of flow control devices. Obtained new data bank have been used for the comparison with available simulation techniques, starting from RANS, through URANS, LES and hybrid RANS-LES methods. New understanding of flow physics as well as ability of different numerical methods in the prediction of such unsteady flow phenomena will be discussed.



Experimental Investigation of Upstream Boundary Layer Acceleration on Unsteadiness of Shock-Induced Separation

Author :

Publisher :

Page : 23 pages

File Size : 38,19 MB

Release : 2003

Category :

ISBN :

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Book Description

This project was aimed at understanding the fundamental cause of the low frequency unsteadiness present in shock-induced turbulent separated flows. A new multi-camera, multi-laser PIV system was used to capture wide-field images of the velocity field in a Mach 2 compression ramp interaction. The PIV was acquired simultaneously with fast-response pressure measurements to identify the shock-foot location at the same time that the PIV data were captured. The measurements showed that the global structure of the interaction was substantially different depending on the location of the separation shock foot. For example, when the shock is upstream, the scale of the separated flow, the velocity fluctuations and the domain of perturbed flow, are all substantially larger than when the shock-foot is located downstream. Most importantly, a clear correlation was observed between the thickness and velocity profile in the upstream boundary layer and the shock foot position. A new technique for measuring the upstream boundary layer acceleration by using two-frame time-sequenced PIV was also developed. This involved developing new hardware and software tools, and conducting preliminary calibration experiments. This work has shown the feasibility of correlating the upstream acceleration to the shock motion and these measurements will be made in future work.



31st International Symposium on Shock Waves 1

Author : Akihiro Sasoh

Publisher : Springer

Page : 1188 pages

File Size : 29,2 MB

Release : 2019-03-21

Category : Technology & Engineering

ISBN : 3319910205

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Book Description

This is the first volume of a two volume set which presents the results of the 31st International Symposium on Shock Waves (ISSW31), held in Nagoya, Japan in 2017. It was organized with support from the International Shock Wave Institute (ISWI), Shock Wave Research Society of Japan, School of Engineering of Nagoya University, and other societies, organizations, governments and industry. The ISSW31 focused on the following areas: Blast waves, chemical reacting flows, chemical kinetics, detonation and combustion, ignition, facilities, diagnostics, flow visualization, spectroscopy, numerical methods, shock waves in rarefied flows, shock waves in dense gases, shock waves in liquids, shock waves in solids, impact and compaction, supersonic jet, multiphase flow, plasmas, magnetohyrdrodynamics, propulsion, shock waves in internal flows, pseudo-shock wave and shock train, nozzle flow, re-entry gasdynamics, shock waves in space, Richtmyer-Meshkov instability, shock/boundary layer interaction, shock/vortex interaction, shock wave reflection/interaction, shock wave interaction with dusty media, shock wave interaction with granular media, shock wave interaction with porous media, shock wave interaction with obstacles, supersonic and hypersonic flows, sonic boom, shock wave focusing, safety against shock loading, shock waves for material processing, shock-like phenomena, and shock wave education. These proceedings contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 31 and individuals interested in these fields.



High Order Large Eddy Simulation for Shock-Boundary Layer Interaction Control by a Micro-ramp Vortex Generator

Author : Chaoqun Liu

Publisher : Bentham Science Publishers

Page : 321 pages

File Size : 17,87 MB

Release : 2017-12-08

Category : Technology & Engineering

ISBN : 1681085976

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Book Description

This volume presents an implicitly implemented large eddy simulation (ILES) by using the fifth order bandwidth-optimized WENO scheme. The chosen method is applied to make comprehensive studies on ramp flows with and without control at Mach 2.5 and Re=5760. Flow control in the form of microramp vortex generators (MVG) is applied. The results show that a MVG can distinctly reduce the separation zone at the ramp corner and lower the boundary layer shape factor under simulated conditions. A series of new findings about the MVG-ramp flow are obtained, including structures relevant to surface pressure, three-dimensional structures of the re-compression shock waves, a complete surface separation pattern, momentum deficit and a new secondary vortex system. A new mechanism of shock-boundary layer interaction control by MVG associated with a series of vortex rings is also presented. Vortex rings strongly interact with air flow and play an important role in the separation zone reduction. Additionally, readers will learn about the governing equation, boundary condition, high quality grid generation, high order shock capturing scheme and DNS inflow condition in detail. This volume will, therefore, serve as a useful reference for aerospace researchers using LES methods to study shock boundary layer interaction and supersonic flow control.





Understanding Micro-Ramp Control for Shock Boundary Layer Interactions

Author :

Publisher :

Page : 29 pages

File Size : 14,16 MB

Release : 2008

Category :

ISBN :

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Book Description

Micro-vortex generators (micro-VGs) have the ability to alter the near-wall structure of compressible turbulent boundary layers in such a way that the flow becomes significantly less susceptible to separations and more stable to unsteady disturbances. Due to their extremely small size, micro-VGs are embedded in the boundary layer and may provide reduced viscous drag when compared to traditional vortex generators. Of several candidate micro-VGs, micro-ramps have been found to significantly impact shock boundary layer interaction flows, while being cost-effective, physically robust, and requiring no power sources. Thus detailed study of flow interactions with micro-ramps on a supersonic boundary layer at M=3.0 was investigated using monotone integrated Large Eddy Simulations (MILES) and Reynolds Averaged Navier-Stokes (RANS). A rescale-recycle method was used to efficiently generate turbulent in-flow conditions. Studies showed that the vortical structure generated from the micro-ramp flows through the separation region caused by the impinging shock, which helped to reduce the area of separation.