Author: Ashish NedungadiPublisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 468
Book Description
A Computational Study of Oblique Shock/vortex Interactions and Its Application for Supersonic Mixing Enhancement
Author: Ashish NedungadiPublisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 468
Book Description
Computational Study of Three-dimensional Oblique Shock Wave/vortex Interaction
Author: Ashish NedungadiExperimental and Computational Investigation of Oblique Shock-vortex Interaction
Author: Michael KlaasVortex Dynamics Studies in Supersonic Flow
Author: Fabrizio VerginePublisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 213
Book Description
Despite the recognized importance of streamwise vortices in the enhancement of fuel/air mixing processes in scramjet combustors, the effects of their interactions and dynamics on mixing and associated total pressure losses are still relatively unexplored. This work presents the first systematic effort to find answers to fundamental questions such as: can selected vortex interactions be identified and effectively used in an injection system for scramjets? Is the increase of streamwise vorticity content, regardless of its spatial distribution in the flow, always beneficial for entrainment and molecular mixing? Is it possible to apply vortex dynamics concepts in reacting flows? For this reason the dissertation covers the study of selected vortex interaction scenarios both in cold and high enthalpy reacting flows. Specifically, the experimental results and the analysis of the flowfields resulting from two selected supersonic vortex interaction modes in a Mach 2.5 cold flow are presented. Additionally, the experiment design based on vortex dynamics concepts and the reacting plume survey of two pylon injectors in a Mach 2.4 high enthalpy flow are shown. The cold flow experiments were conducted in the supersonic wind tunnel of the Aerodynamics Research Center at the University of Texas at Arlington. A strut injector equipped with specified ramp configurations was designed and used to produce the flowfields of interest. The reacting flow experiments were conducted in the Expansion Tube Facility located in the High Temperature Gasdynamics Laboratory of Stanford University. A detailed description of the supersonic wind tunnel, the instrumentation, the strut injector and the supersonic wake flow downstream is shown as part of the characterization of the facility. As stereoscopic particle image velocimetry was the principal flow measurement technique used in this work to probe the streamwise vortices shed from ramps mounted on the strut, this dissertation provides a deep overview of the challenges and the application of the aforementioned technique to the survey of vortical flows. Moreover, the dissertation provides a new and comprehensive analysis of the flow physics associated with these complex supersonic vortical interactions. The mean and fluctuating velocity flowfields of two selected vortex dynamics scenarios, chosen based on the outcomes of the simulations of an inviscid reduced order model developed in the research group, are presented. The same streamwise vortices (strength, size and Reynolds number) were used experimentally to investigate both a case in which the resulting dynamics evolve in a vortex merging scenario and a case in which the merging process is voluntarily avoided in order to focus the analysis on the fundamental differences associated with the amalgamation processes alone. The results from the mean flow highlight major differences between the two cases and corroborate the use of an inviscid model for the prediction of the main flow physics in the times scales considered. The analysis is also extended to turbulence quantities and concepts borrowed from incompressible turbulence theory (i.e., fluctuating Mach numbers “ 1) appear to explain interesting features of the fluctuating flowfields. Once the interactions among the vortical structures in cold flow were assessed, these vortex dynamics concepts were probed in a reacting environment. The dissertation describes the design phase of two pylon injectors based on the prediction capabilities of the aforementioned model. Then, the results of a set of combustion experiments conducted utilizing hydrogen fuel injected into a Mach 2.4, high-enthalpy (2.8 MJ/kg) air flow are discussed. The results show that, for the heat release levels considered in this study, the morphology of the plume and its evolution are remarkably close to the results produced by the model, enabling an interpretation based on vortex dynamics considerations. The persistence of the streamwise vortical structures created by the selected ramp configurations is shown together with the effectiveness of the coherent structures in successfully anchoring the flame very close to the injection point. The work shows the possibility of a new approach in the design of injection strategies (not limited to injection devices) suitable for adoption in scramjet combustors based on the ability to predict, with basic vortex dynamics concepts and a highly reduced computational cost, the main features of flows of technological interest.
Investigations Into Shock-induced Enhancement of Mixing and Combustion in Supersonic Burners
Author: Frank E. MarblePublisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 44
Book Description
A Computational Study on the Interaction Between a Vortex and a Shock Wave
Author: Kristine R. MeadowsScientific and Technical Aerospace Reports
Author: Analytical and Experimental Studies on Mixing in Supersonic Flows
Author: Vijay GopalPublisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 175
Book Description
Mixing enhancement in supersonic flow is an important domain of research for enabling the realization of efficient and scalable high speed air-breathing engines (scramjet).Introducing streamwise vorticies in supersonic flow and tailoring their interactions for mixing enhancement is the primary motivation for the present research study. Leveraging the research performed in the group at the Aerodynamics Research Center (ARC), systematic experimental studies on mixing enhancement is carried out in supersonic flows by tailoring the selected modes of stream wise vortex interactions with the aid of in-house developed reduced order method VorTX. This method utilizes the lifting line-vortex theory in supersonic flow to perform rapid simulations of streamwise vortex-interactions that serves as a guide to design the mixing experiments. One of the difficulties associated with scaling the simulations to higher Mach numbers (M > 4) arise from the strong influence of the singularities along the Mach cones emanating from the lifting line-vortex that results in physically inconsistent solution. In this work a fundamental study on vorticity distribution in linearized supersonic flow is carried out. The origin of the aforementioned singularities on the Mach cone is discussed in detail, and the potential candidates for vorticity distribution are proposed to eliminate the singularities and to provide a physically consistent solution of the flow field in supersonic flow. This study presents the successful solution for the elimination of the singularities that has allowed to extend the capability of VorTX to simulate vortex-interactions at higher Mach numbers. Experimental studies on supersonic mixing were carried out using a strut injection platform with vortex generating ramps to introduce streamwise voriticies in supersonic flow. The geometrical configuration of the ramps are chosen using the upgraded VorTX simulations to target the experimental study of two selected modes of vortex interactions. One is the merging of two co-rotating vorticies and the other is the non-merging case where the vorticies interact but do not merge. Mixing measurements in supersonic flow were carried out using the Filtered Rayleigh Scattering (FRS)technique. The measurement yields the mole-fraction of helium (injectant) in a binary mixture of air and helium in supersonic flow. The distributions of helium mole-fraction in the cross flow planes are used to draw conclusions on the level of mixing in the two modes of vortex-interaction. The FRS technique requires two independent experiments. One with helium injection in supersonic air flow and the other with air injection in an identical supersonic air flow. At a given cross-flow plane, to obtain the helium mole-fraction distribution using the FRS signals it is assumed that the total number density is matched in both the experiments. To enhance the reliability of the FRS measurement technique, it is important to minimize and quantify the systematic errors that arise from the assumptions made, particularly, the assumption on matching the total number density. In this work, a method to reduce the systematic errors in FRS experiments is proposed for a canonical case study of a rectangular jet in supersonic flow. To do this, a reduced order model for a rectangular jet in supersonic air flow is successfully developed in order to guide the selection of appropriate injector's plenum conditions to minimize the systematic errors in the future FRS experiments and to retrospectively evaluate and correct the FRS measurements for systematic errors in previously available FRS data on parallel strut injection in supersonic flow.
Shock Wave-Boundary-Layer Interactions
Author: Holger BabinskyPublisher: Cambridge University Press
ISBN: 1139498649
Category : Technology & Engineering
Languages : en
Pages : 481
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.
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 876
Book Description