Download or read book Optimization of Passive Flow Control Technique for Enhanced Turbulent Mixing in Supersonic Propulsion written by Andrious Nelson and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Author's abstract: Scramjets are supersonic combustion ramjets where there is no mechanical compressor to compress air for combustion. The technology behind engines flying at supersonic speeds has been explored since 1947. It has been in only recent years where the computational power is great enough to handle the challenges. One main challenge with engines is the problem of efficiency. The research conducted explores the background information of scramjets and significant flow field characteristics to optimize the turbulent mixing efficiency. A computational domain was chosen based on a study that revealed that adding dimpled surfaces upstream of a cavity flame holder would suppress pressure oscillations. Suppressing pressure oscillations causes less damage done to the structure of the scramjet engine and reduce the aeroacoustics generated. The research done intends to optimize the dimple diameter and dimple depth to increase mixing found in the cavity. Eight models were created by increasing or decreasing the dimple diameter from 20 mm and increasing the dimple depth from 6 mm. Each case was simulated at freestream velocities, 25 m/s, 35 m/s, 45 m/s, and 55m/s. The velocity contour and vectors showed that the L/D ratio of less than 10 followed the same characteristics of an open cavity where there are two main recirculation regions found in the cavity. Analyzing the pressure identified that the drag inside of a scramjet engine is less when there are dimpled surfaces. Turbulent eddy dissipation and turbulent eddy frequency confirmed that there were recirculation regions of larger eddies found inside the dimples. The skin friction coefficient revealed that adding dimples, increased flow separation in the cavity close to the trailing edge and adds flow separation or mixing at the dimples. To reduce drag and increase mixing in the scramjet engine case Dia20d10 was chosen. This case showed no apparent effects due to increased freestream velocity along the trailing edge of the cavity and increased mixing at the leading edge.

Download or read book Coupling of Vortex Flows with Control Jets for Enhanced Mixing and Flame Holding in Supersonic Flows written by Thomas Paul Fetterhoff and published by . This book was released on 2018 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study presents results of innovative integration of passive and active flow physics to accomplish effective supersonic mixing. The study is continuing cavity flow control research in the supersonic wind tunnel at the University of Tennessee Space Institute (UTSI). Initially numerical simulations were employed in support of choosing and refining the experimental configuration designs. Mixing enhancement was achieved through innovative coupling of aerodynamics of corner vortex flows and cavity flow control jets. The two geometries were chosen for their potential to generate strong streamwise vortices, weaker shock losses, low drag, and cavity recirculation zones. Another consideration was that the two physically different concepts would be studied to provide better understanding of the innovative mixing. Jets, simulating fuel injection, were used for flow control provided through penetrations in the front face and side walls of the cavity. Flow visualization, dynamic pressure (sound pressure level) data are measured and PIV measurements are presented and compared with computational predictions for several geometries. High frequency dynamic pressure data were recorded to determine the cavity flow acoustic patterns. Measurements were acquired by a digital data acquisition system from two dynamic pressure transducers, located at different locations on the floor of the cavity. PIV measurements of selected configurations were performed. Schlieren and PIV images, pressure spectra and 2-D PIV data obtained are used as a basis for understanding the flow processes involved and comparison for improving the overall mixing and penetration performance. Streamwise vortices were generated using two different innovatively designed geometries, strategically located upstream of selected cavity configurations, including various jet arrangements, simulating fuel flow and control. Both configurations tested developed relatively strong streamwise vortex flows and weakened or lofted shear layers, indicating that mixing was enhanced. The two configurations exhibited flow changes with the simulated fuel injection. However, different injection arrangements by the simulated fuel jets resulted in different details in the flow fields and their resulting acoustic spectra. The resulting flow fields show improved potential for fuel flow mixing and increased penetration while amplifying or attenuating flow unsteadiness in the cavity.

Download or read book Turbulent Shear Layers in Supersonic Flow written by Alexander J. Smits and published by Springer Science & Business Media. This book was released on 2006-05-11 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: A good understanding of turbulent compressible flows is essential to the design and operation of high-speed vehicles. Such flows occur, for example, in the external flow over the surfaces of supersonic aircraft, and in the internal flow through the engines. Our ability to predict the aerodynamic lift, drag, propulsion and maneuverability of high-speed vehicles is crucially dependent on our knowledge of turbulent shear layers, and our understanding of their behavior in the presence of shock waves and regions of changing pressure. Turbulent Shear Layers in Supersonic Flow provides a comprehensive introduction to the field, and helps provide a basis for future work in this area. Wherever possible we use the available experimental work, and the results from numerical simulations to illustrate and develop a physical understanding of turbulent compressible flows.

Download or read book Flow Control Techniques and Applications written by Jinjun Wang and published by Cambridge University Press. This book was released on 2019 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master the theory, applications and control mechanisms of flow control techniques.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA SP written by and published by . This book was released on 1992 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study on the Turbulence Characteristics and Mixing Performance of Streamwise Vortex Interactions in Supersonic Flow written by Cody R. Ground and published by . This book was released on 2019 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: The scramjet engine offers the unique capability to enable sustained air breathing flight at hypersonic speeds. However, in order to reach its full application potential, further technological maturation of several system level components is necessary. One such component is the fuel injection system. The flow conditions characteristic of the scramjet combustor are such that the rate-limiting step in the fuel injection/mixing/combustion process is the mixing of the fuel and air. For this reason, the fuel injection system must be designed with the goal of enhancing the rate of fuel/air mixing. One method that has shown potential to enhance fuel/air mixing in supersonic flows is the introduction of streamwise vorticity into the mixing field, yet there are many fundamental aspects of this concept that remain relatively uninvestigated. One such aspect is the capability to use specific streamwise vortex interaction modes to synergistically increase mixing in the flow. However, in order to target specific vortex interactions which act to enhance mixing in the design stage of a fuel injection system a better foundational knowledge of streamwise vortex interactions in supersonic flows must be obtained. To this end, this dissertation presents a fundamental experimental investigation into two elemental modes of vortex interaction, the merging and non-merging of a pair of co-rotating streamwise vortices. The experimental investigations were all conducted at the University of Texas at Arlington Aerodynamics Research Center in the blow-down Supersonic Wind Tunnel Facility which delivered a Mach 2.5 free stream flow for all of the experiments detailed herein. To create the targeted vortex interaction modes specific configurations of vortex generating ramps were affixed to the trailing edge of a strut injector. The experiments detailed in this dissertation accomplish two tasks in the continuation of the group's previous research on the merging and non-merging modes of streamwise vortex interaction. The first task that will be presented is the analysis of the fluctuating velocity flow fields of the two studied vortex interactions with the proper orthogonal decomposition (POD) technique. This analysis is approached in order to quantify the organization and relative turbulent kinetic energy content of the various scales of turbulent coherent structures of the flow. The results of the POD analysis revealed that the vortex merging process reorients and redistributes the turbulent kinetic energy content towards the larger coherent structures captured in the low-order eigenmodes of the POD. The second task presented in this dissertation is the non-intrusive laser-based quantification of the mixing performance of the two vortex interactions using the filtered Rayleigh scattering (FRS) technique. Applying the FRS technique to retrieve mixture composition measurements in highly complex flows such as the flows studied here is a nontrivial task. For this reason, experiments were initially performed in a canonical two-dimensional planar shear layer to compare the relative accuracy of filtered Rayleigh scattering measurements with intrusive gas-sampling based mixture composition measurements. With this comparison yielding good levels of agreement between the two techniques, the FRS technique was able to be confidently applied in the vortical flows of primary interest. The main conclusion obtained from the FRS experiments was the finding that the non-merging vortex interaction more rapidly mixes the fuel and air due to its increased rate of entrainment with respect to the merging vortex interaction. Taken together, the results of the two analyses presented in this dissertation highlight the necessity of considering streamwise vortex interactions in the design stage of scramjet fuel injection systems since all differences in the flowfields of the two studied cases arise solely due to the different vortex interaction modes generated. Most importantly, this work has laid the foundation for future fundamental vortex dynamics studies which seek to optimize these (and other) modes of interaction by using the analysis and measurement techniques described herein.

Download or read book Innovative Passive Control Techniques for Supersonic Jet Mixing written by Mrinal Kaushik and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transition and Turbulence Control written by Mohamed Gad-el-Hak and published by World Scientific. This book was released on 2006 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains articles based on lectures given at the Workshop on Transition and Turbulence Control, hosted by the Institute for Mathematical Sciences, National University of Singapore, 8-10 December 2004. The lecturers included 13 of the world's foremost experts in the control of transitioning and turbulent flows. The chapters cover a wide range of subjects in the broad area of flow control, and will be useful to researchers working in this area in academia, government laboratories and industry. The coverage includes control theory, passive, active and reactive methods for controlling transitional and turbulent wall-bounded flows, noise suppression and mixing enhancement of supersonic turbulent jets, compliant coatings, modern flow diagnostic systems, and swept wing instabilities.

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulent Mixing Layer Experiment in Supersonic Flow written by Hideo Ikawa and published by . This book was released on 1973 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies of Turbulent Mixing and Combustion in Supersonic Heterogeneous Flows written by Kenneth N. C. Bray and published by . This book was released on 1971 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the program was the development of analytical models of various flow configurations which can be used in the design of supersonic air-breathing propulsion systems. The work described in the report represents an extension of earlier studies in the program to conditions that exist in air-augmented rocket systems. These conditions vary according to the nature of the rocket propellant, as liquid propellants usually produce only gaseous fuel-rich combustion products whereas solid propellant rockets emit heterogeneous products which contain small combustible particles. The inclusion of particles produces significant effects upon reacting turbuelent flows, particularly when the particles themselves continue to burn. Some predictions of their behavior in a reacting flow field are presented. A series of systematic tests has been planned by which the experimental conditions proceed stepwise through conditions of increasing primary stream (rocket exhaust) complexity starting with a cold nonreactive gas and ending with a hot, reactive, heterogeneous mixture. The method permits the effects of temperature, of gaseous combustion and solid combustion upon a supersonic, reacting flow field to be isolated. Results obtained from the experimental tests are presented, and some conclusions are drawn from the data. (Author).

Download or read book A Study of the Turbulent Mixing Region of a Supersonic Jet Mixing with a Low Speed Flow written by Hsian-Pei Chou and published by . This book was released on 1972 with total page 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 1991 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Control written by Mohamed Gad-el-Hak and published by Cambridge University Press. This book was released on 2000-08-15 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thorough treatment of the basics of flow control and flow control practices.

Download or read book Aeronautical Engineering A Cumulative Index to a Continuing Bibliography supplement 248 written by and published by . This book was released on 1990 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2668 pages. Available in PDF, EPUB and Kindle. Book excerpt: