Download or read book Schlieren and Planar Laser induced Fluorescence Imaging of Supersonic Mixing Shear Flows with a Passive Mixing Enhancement Technique written by Adam M. Ragheb and published by . This book was released on 2009 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1997 with total page 940 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Final Technical Report on Research on Supersonic Reacting Flows written by and published by . This book was released on 1997 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and computational investigation of supersonic combustion flows was carried out. The principal objective of the research was to gain a more fundamental understanding of mixing and chemical reaction in supersonic flows. The research effort comprised three interrelated elements: (1) stability analyses and numerical simulations of compressible reacting flows; (2) development of laser induced fluorescence techniques for time resolved multidimensional imaging of species concentration, temperature, velocity and pressure; and (3) an experimental study of mixing and combustion in a supersonic plane mixing layer with the additional development of simple mixing enhancements. The specific objectives and results of the research of each of these program elements have been summarized in this report. New results include: (1) a detailed stability map for reacting, compressible shear layers; (2) new PLIF techniques for transient facilities; (3) new measurements of mixing efficiency in compressible flows; and (4) demonstration of simple mixing enhancement techniques with low pressure drop.
Download or read book Research on Supersonic Reacting Flows written by and published by . This book was released on 1995 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and computational investigation of supersonic reacting flows, with the objective of gaining a fundamental understanding of the flow physics and chemistry interactions, is in progress. During the past year, experiments were conducted in a supersonic shear flow facility to visualize the instantaneous, three-dimensional structure of the compressible mixing layer and to measure the mixing efficiency. The mixing efficiency was measured by applying a new planar laser-induced fluorescence (PLIF) technique, termed "cold chemistry." The PLIF techniques, developed previously in our laboratory, were refined to allow measurements of temperature, velocity and multiple species in transient high-speed flows. Current codes for direct numerical simulation of time-developing, three-dimensional, reacting, compressible mixing layers were adapted for a new generation of supercomputers. Previously-developed stability analyses were extended to the range of conditions being investigated in the supersonic reacting flow experiments. (AN).
Download or read book NASA SP written by and published by . This book was released on 1993 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supersonic Mixing Enhancement by Vorticity for High Speed Propulsion written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-16 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a three year study on vortex enhancement of supersonic mixing are discussed. Recent interests in compressible mixing has spurred research in the field of high speed shear layers. It was established that shear layer growth diminishes with increasing convective Mach number; this Mach number is the relative Mach number of the large scale structures in the shear layer with respect to the Mach numbers on either side of the shear layer. The purpose was to evaluate the effect of swirl on compressible mixing rates. Previously analytical and experimental results seem to indicate that swirling flow may significantly modify the shear layer, in some cases resulting in enhanced mixing. Previous studies of the effect of swirl on compressible mixing were incomplete since the amount of swirl in the flowfield was not quantified. This study was undertaken to conclusively determine the effect of swirl on supersonic mixing, including the quantification of the swirl. Preliminary results indicate that the swirl modestly enhances the mixing rates. Settles, Gary S. Unspecified Center...
Download or read book An Experimental Investigation of the Properties of a Non reacting Supersonic Shear Layer written by and published by . This book was released on 1990 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: A shear layer formed by the merging of two different mass density and velocity, supersonic, inert gas streams (Ar and He) was investigated using both intrusive (probes) and non-intrusive (laser-based) techniques. Interpretations based upon mean pitot pressure surveys, namely shear layer growth rate and compressibility agree with established data. An aspirating probe in conjunction with a mass spectrometer comprised a gas sampling system for ultimately obtaining concentration profiles. Rapid scanning of such flows is possible with such a technique but additional efforts are required to make quantitative concentration assignments. The technique does, however, provide a means of qualitatively assessing mixing rates. Finally planar laser-induced fluorescence (PLIF) was used to establish spatially and temporally resolved images of the shear layer. Obtained images demonstrate the usefulness of PLIF to qualitatively monitor turbulent mixing phenomena in supersonic flows. 17 refs., 14 figs.
Download or read book Support for Graduate Research in Supersonic Reacting Flows written by Mark Godfrey Mungal and published by . This book was released on 1998 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work was aimed at obtaining a more fundamental understanding of mixing and combustion in supersonic flows. Advanced laser based techniques for measurements in an existing supersonic shear layer facility were primarily used. The main scientific question addressed was a comparison of the similarities and differences between mixing and reaction when compressibility plays a significant role. To this end, Particle Image Velocimetry (PIV) was used to obtain detailed, whole field velocity measurements under a range of compressibility conditions. These measurements are complementary to earlier measurements of scalar concentrations in similar flows. New observations concerning the nature of the instantaneous velocity and vorticity fields were made as a function of compressibility. In addition, Planar Laser Mie Scattering is used to obtain structure velocity measurements for comparison with the actual fluid velocities.
Download or read book Research on Supersonic Reacting Rows written by and published by . This book was released on 1997 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and computational investigation of supersonic combustion flows was carried out. The principal objective of the research was to gain a more fundamental understanding of mixing and chemical reaction in supersonic flows. The research effort comprised three inter-related elements: (1) stability analyses and numerical simulations of compressible reacting flows; (2) development of laser-induced fluorescence techniques for time-resolved multidimensional imaging of species concentration, temperature, velocity and pressure; and (3) an experimental study of mixing and combustion in a supersonic plane mixing layer with the additional development of simple mixing enhancements. The specific objectives and results of the research of each of these program elements have been summarized in this report. New results include: a detailed stability map for reacting, compressible shear layers; new PLIF techniques for transient facilities; new measurements of mixing efficiency in compressible flows and demonstration of simple mixing enhancement techniques with low pressure drop.
Download or read book Development of Scalar and Velocity Imaging Diagnostics for Supersonic Hypermixing Strut Injector Flowfields written by Ross Andrew Burns and published by . This book was released on 2014 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new diagnostic technique for studying the turbulent mixing characteristics of supersonic mixing flowfields is developed and implemented in two Mach 3 mixing flowfields. The diagnostic utilizes simultaneous particle image velocimetry and quantitative planar laser-induced fluorescence of krypton gas to study the interaction between turbulent scalar and velocity fields. The fluorescence properties of krypton gas are determined; measurements of the pressure and temperature dependence of the collisional quenching rates and cross-sections are made for various mixtures with krypton. The gases tested in this fashion include helium, nitrogen, air, oxygen, and ethylene. Additional measurements are performed to measure the relative two-photon absorption cross-section for krypton gas. The non-dimensional quenching rates are found to follow a power-law dependence for temperature, while the pressure dependence of the total quenching rate is found to be linear. Two injection flowfields are studied for their general topology and kinematic characteristcs. The first injector model is a basic injector meant to serve as a baseline case; there are no hypermixing elements present in this model. The second model is an asymmetric, unswept hypermixing injector featuring 15 degree expansive ramps flanking a central block. These studies utilize particle image velocimetry in planar and stereoscopic configurations in various planes. Results for the mean flowfield show distinct differences between the two flowfields; the planar injector flowfield is shown to be highly two-dimensional and exhibits minimal coherent unsteady behavior. The hypermixing injector flowfield exhibits a highly three-dimensional wake, with a pair of stream-wise vortices driving both mean deviations in the flowfield and considerable vortical coupling in the span-wise direction. Simultaneous krypton PLIF and PIV are employed in the two mixing flowfields. An assay of the dependence of the krypton mole fraction calculations on the fluorescence signal is performed. The overall sensitivity and the resulting dynamic range of the calibration is dictated largely by the reference mole fraction. Additionally, several different theoretical models of the temperature dependence of the fluorescence signal are studied to assess their validity and influence over the PLIF calibration procedure. Finally, the technique is employed in the two mixing flowfields, and a brief analysis of the mean and unsteady behavior of the two is conducted.
Download or read book Analytical and Experimental Studies on Mixing in Supersonic Flows written by Vijay Gopal and published by . This book was released on 2021 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Turbulent Reacting Flows and Supersonic Combustion written by and published by . This book was released on 1993 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and computational investigation of supersonic combustion flows has been carried out. The principal objective of the research was to gain a more fundamental understanding of mixing and chemical reaction in supersonic flows. The research effort comprised three inter-related elements: (1) an experimental study of mixing and combustion in a supersonic plane mixing layer; (2) development of laser-induced fluorescence techniques for time- resolved multidimensional imaging of species concentration, temperature, velocity and pressure; and, (3) analyses and numerical simulations of compressible reacting flows. The specific objectives and results of the research of each of these program elements are summarized in this report. Supersonic combustion, Turbulent reacting flows, Shear layers, Laser diagnostics.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1992 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Resolution Measurements of Supersonic Shear Flow Mixing and Combustion written by and published by . This book was released on 2001 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation of compressibility effects on the large-scale structure scaling laws, and entrainment and mixing rates in supersonic, planar, turbulent, bluff-body wakes was conducted. The compressibility effects in supersonic wakes were found to differ significantly from those in supersonic mixing layers. Results at free stream Mach numbers 2 and 3 showed that the large-scale structure of incompressible turbulent wakes was recovered in supersonic wakes at downstream locations where the local Mach number became sufficiently small. No organized large-scale structure was found where the local Mach number was greater than O.7. Unlike supersonic mixing layers, the results showed that the principal effect of compressibility in supersonic wakes was a local self-induced forcing, where reflected expansion waves from the near-field recompression region intersected the wake.
Download or read book Direct Numerical Simulation of Mixing Enhancement in Supersonic Shear Flows written by Iok Leng Lee and published by . This book was released on 2012 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeronautical Engineering written by and published by . This book was released on 1993 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)
