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In accordance with the project plan for the report period in the proposal titled above, HU and FML teams investigated two sets of concepts for reduction of noise and improvement in efficiency for jet exhaust nozzles of aircraft engines and screws for mixers, fans, propellers and boats. The main achievements in the report period are: (a) Publication of the paper in the AIAA Journal, which described our concepts and some results. (b) The Award in the Civil Research and Development Foundation (CRDF) competition. This 2 year grant for Hampton University (HU) and Central AeroHydrodynamic Institute (TSAGI, Moscow, Russia) supports the research implementation under the current NASA FAR grant. (c) Selection for funding by NASA HQ review panel of the Partnership Awards Concept Paper. This two year grant also will support our current FAR grant. (d) Publication of a Mobius Strip concept in NASA Technical Briefs, June, 1996, and a great interest of many industrial companies in this invention. Successful experimental results with the Mobius shaped screw for mixers, which save more than 30% of the electric power by comparison with the standard screws. Creation of the scientific-popular video-film which can be used for commercial and educational purposes. (e) Organization work, joint meetings and discussions of the NASA LARC JNL Team and HU professors and administration for the solution of actual problems and effective work of the Fluid Mechanics Laboratory at Hampton University. In this report the main designs are enumerated. It also contains for both concept sets: (1) the statement of the problem for each design, some results, publications, inventions, patents, our vision for continuation of this research, and (2) present and expected problems in the future.

This paper discusses Advanced Aircraft configurational approaches across the speed range, which are either enabled, or greatly enhanced, by clever Flow Control. Configurations considered include Channel Wings with circulation control for VTOL (but non-hovering) operation with high cruise speed, strut-braced CTOL transports with wingtip engines and extensive ('natural') laminar flow control, a midwing double fuselage CTOL approach utilizing several synergistic methods for drag-due-to-lift reduction, a supersonic strut-braced configuration with order of twice the L/D of current approaches and a very advanced, highly engine flow-path-integrated hypersonic cruise machine. This paper indicates both the promise of synergistic flow control approaches as enablers for 'Revolutions' in aircraft performance and fluid mechanic 'areas of ignorance' which impede their realization and provide 'target-rich' opportunities for Fluids Research.

As described in previous reports, this AASERT funding has provided support for graduate student training in high speed optical flow diagnostics. Funds were provided for the purchase of a 20 MHz rate framing camera (Hadland Imacon 792), which was used to capture a pair of rapidly sequenced Rayleigh scattering images, using a double pulsed Nd:YAG laser system purchased from parent grant AFOSR support. During the current reporting period, work has progressed on a synergistic program to develop a 'burst mode' laser system, which will, ultimately, provide the capability to obtain approximately 30 rapidly sequenced images. This work is closely coupled with the parent grant (#F4962O0-92-J-0217) and a collaborative AFOSR program with Profs. Alexander Smits and Garry Brown (F49620-93-1-0064).

FLUID

Under this award the fluid mechanics measurement capabilities of the combustion and fuels laboratory of the University of Southern California were upgraded notably. Thus, the needs for determining flame properties of fundamental and practical importance can be met readily. The experimental data so obtained will be used for the validation of chemical kinetic and diffusion models for hydrocarbon fuels used in air-breathing devices that are of interest to the Air Force; furthermore, the data contain important information related to the performance of various practical fuels and will be useful in defining the operational range of advanced propulsion systems, such as scramjets. The acquired instrumentation involves high-resolution, high accuracy laser-based systems and subsystems and constitutes a major improvement of current capabilities in the principal investigator's (PI's) laboratory. This improvement enhances the quality of ongoing research that is conducted under AFOSR support significantly. Three state-of- the-art velocity measurement systems were developed to complement an existing digital particle image velocimetry (DPIV) system that was acquired previously under AFOSR support. The first velocity measurement system is a compact laser Doppler velocimeter (LDV). The other two are DPIV systems, which were developed around a high-power YAG laser that is available to the PI at no cost to AFOSR. After determining the velocity fields in flames, fundamental flame properties can be derived, such as laminar flame speeds, as well as ignition and extinction limits. The sensitivity of those properties to both chemical kinetics and molecular transport can be large, so that validation and/or optimization of various models can be achieved. The parameter space of the PI's ongoing research is extensive, as it involves a large number of fuels, such as neat hydrocarbons, jet fuels and their surrogates, fuel-air ratios, initial reactant temperatures, and thermodynamic pressures.

Under this award the fluid mechanics measurement capabilities of the combustion and fuels laboratory of the University of Southern California were upgraded notably. Thus, the needs for determining flame properties of fundamental and practical importance can be met readily. The experimental data so obtained will be used for the validation of chemical kinetic and diffusion models for hydrocarbon fuels used in air-breathing devices that are of interest to the Air Force; furthermore, the data contain important information related to the performance of various practical fuels and will be useful in defining the operational range of advanced propulsion systems, such as scramjets. The acquired instrumentation involves high-resolution, high accuracy laser-based systems and subsystems and constitutes a major improvement of current capabilities in the principal investigator's (PI's) laboratory. This improvement enhances the quality of ongoing research that is conducted under AFOSR support significantly. Three state-of- the-art velocity measurement systems were developed to complement an existing digital particle image velocimetry (DPIV) system that was acquired previously under AFOSR support. The first velocity measurement system is a compact laser Doppler velocimeter (LDV). The other two are DPIV systems, which were developed around a high-power YAG laser that is available to the PI at no cost to AFOSR. After determining the velocity fields in flames, fundamental flame properties can be derived, such as laminar flame speeds, as well as ignition and extinction limits. The sensitivity of those properties to both chemical kinetics and molecular transport can be large, so that validation and/or optimization of various models can be achieved. The parameter space of the PI's ongoing research is extensive, as it involves a large number of fuels, such as neat hydrocarbons, jet fuels and their surrogates, fuel-air ratios, initial reactant temperatures, and thermodynamic pressures.

ADVANCED FLUID MECHANICS

ADVANCED FLUID MECHANICS