Correlation analysis of separation shock oscillation and wall pressure fluctuation in unstarted hypersonic inlet flow

The flow field in a hypersonic inlet model at a design point of M = 6 has been studied experimentally. The focus of the current study is to present the time-resolved flow characteristics of separation shock around the cowl and the correlation between the separation shock oscillation induced by the unstart flow and the wall pressure fluctuation when the inlet is in a state of unstart. High-speed Schlieren flow visualization is used to capture the transient shock structure. High-frequency pressure transducers are installed on the wall around both the cowl and isolator areas to detect the dynamic pressure distribution. A schlieren image quantization method based on gray level detection and calculation is developed to analyze the time-resolved spatial structure of separation shock. Results indicate that the induced separation shock oscillation and the wall pressure fluctuation are closely connected, and they show the same frequency variation characteristics. The unsteady flow pattern of the “little buzz” and “big buzz” modes are clarified based on time-resolved Schlieren images of separation shock. Furthermore, the appropriate location of the pressure transducers is determined on the basis of the combined analysis of fluctuating wall-pressure and oscillating separation shock data

Fuel Injection

Fuel Injection is a key process characterizing the combustion development within Internal Combustion Engines (ICEs) and in many other industrial applications. State of the art in the research and development of modern fuel injection systems are presented in this book. It consists of 12 chapters focused on both numerical and experimental techniques, allowing its proper design and optimization

Microfluidics and Nanofluidics Handbook

The Microfluidics and Nanofluidics Handbook: Two-Volume Set comprehensively captures the cross-disciplinary breadth of the fields of micro- and nanofluidics, which encompass the biological sciences, chemistry, physics and engineering applications. To fill the knowledge gap between engineering and the basic sciences, the editors pulled together key individuals, well known in their respective areas, to author chapters that help graduate students, scientists, and practicing engineers understand the overall area of microfluidics and nanofluidics. Topics covered include Finite Volume Method for Numerical Simulation Lattice Boltzmann Method and Its Applications in Microfluidics Microparticle and Nanoparticle Manipulation Methane Solubility Enhancement in Water Confined to Nanoscale Pores Volume Two: Fabrication, Implementation, and Applications focuses on topics related to experimental and numerical methods. It also covers fabrication and applications in a variety of areas, from aerospace to biological systems. Reflecting the inherent nature of microfluidics and nanofluidics, the book includes as much interdisciplinary knowledge as possible. It provides the fundamental science background for newcomers and advanced techniques and concepts for experienced researchers and professionals

Aeronautical engineering: A continuing bibliography with indexes (supplement 321)

This bibliography lists 496 reports, articles, and other documents introduced into the NASA scientific and technical information system in Sep. 1995. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Bibliography of Lewis Research Center technical publications announced in 1992

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1992. All the publications were announced in the 1992 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses

An understanding of ejector flow phenomena for waste heat driven cooling

In an attempt to reduce the dependence on fossil fuels, a variety of research initiatives has focused on increasing the efficiency of conventional energy systems. One such approach is to use waste heat recovery to reclaim energy that is typically lost in the form of dissipative heat. An example of such reclamation is the use of waste heat recovery systems that take low-temperature heat and deliver cooling in space-conditioning applications. In this work, an ejector-based chiller driven by waste heat will be studied from the system to component to sub-component levels, with a specific focus on the ejector. The ejector is a passive device used to compress refrigerants in waste heat driven heat pumps without the use of high grade electricity or wear-prone complex moving parts. With such ejectors, the electrical input for the overall system can be reduced or eliminated entirely under certain conditions, and package sizes can be significantly reduced, allowing for a cooling system that can operate in off-grid, mobile, or remote applications. The performance of this system, measured typically as a coefficient of performance, is primarily dependent on the performance of the ejector pump. This work uses analytical and numerical modeling techniques combined with flow visualization to determine the exact mechanisms of ejector operation, and makes suggestions for ejector performance improvement. Specifically, forcing the presence of two-phase flow has been suggested as a potential tool for performance enhancement. This study determines the effect of two-phase flow on momentum transfer characteristics inside the ejector while operating with refrigerants R134a and R245fa. It is found that reducing the superheat at motive nozzle inlet results in a 12-13% increase in COP with a 14-16 K decrease in driving waste heat temperature. The mechanisms of this improvement are found to be a combination of two effects: the choice of operating fluid (wet vs. dry) and the effect of two-phase flow on the effectiveness of momentum transfer. It is recommended that ejector-based chillers be operated such that the motive nozzle inlet is near saturation, and environmentally friendly dry fluids such as R245fa be used to improve performance. This work provides critical methods for ejector modeling and validation through visualization, as well as guidance on measures to improve ejector design with commensurate beneficial effects on cooling system COP.Ph.D

Fifth International Microgravity Combustion Workshop

This conference proceedings document is a compilation of 120 papers presented orally or as poster displays to the Fifth International Microgravity Combustion Workshop held in Cleveland, Ohio on May 18-20, 1999. The purpose of the workshop is to present and exchange research results from theoretical and experimental work in combustion science using the reduced-gravity environment as a research tool. The results are contributed by researchers funded by NASA throughout the United States at universities, industry and government research agencies, and by researchers from at least eight international partner countries that are also participating in the microgravity combustion science research discipline. These research results are intended for use by public and private sector organizations for academic purposes, for the development of technologies needed for the Human Exploration and Development of Space, and to improve Earth-bound combustion and fire-safety related technologies

Aeronautical engineering: A continuing bibliography with indexes (supplement 218)

This bibliography lists 469 reports, articles, and other documents introduced into the NASA scientific and technical information system in September, 1987

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences