Index to NASA tech briefs, 1971

The entries are listed by category, subject, author, originating source, source number/Tech Brief number, and Tech Brief number/source number. There are 528 entries

Oscillating Foil Propulsion

In this thesis, an investigation on the use of oscillating foil propulsion for marine vehicle as an alternate effective propulsion system is presented. Three different oscillating foil propellers, namely: two-dimensional oscillating foil propeller; flexible fin propeller, and rotary foil propeller, have been studied. The thesis is made up of four parts: one related to each type of propeller and one on the application of oscillating foil propellers along with general conclusions. Two-Dimensional Oscillating Foil Propeller A review on the hydrodynamic forces and moments acting on a two-dimensional oscillating foil is presented. The equations for estimating the force system have been extended to cover different phase lags between heave and pitch and to calculate the force system at a particular instant of time within an oscillating cycle. The sensitivity of the propulsive thrust coefficient and the hydromechanical efficiency has been investigated for a range of different parameters. The operating condition for optimum performance is identified. Flexible Fin Propeller The theoretical model of the flexible fin propeller, which has been set up by combining linearised unsteady foil theory and large deflection beam theory, is described. Non-dimensional parameters are established to study the performance of this type of propeller. A flexible fin propeller model and its test rig was designed and built. The model was tested in the Hydrodynamics Laboratory at the Department of Naval Architecture and Ocean Engineering, the University of Glasgow. The performance of the propeller was examined at both forward and zero speeds. Results have been compared with theoretical predictions. Conclusions on the performance of the flexible fin propeller are drawn based on the theoretical predictions and experimental results. The stress acting on the flexible bar has been computed and discussed. The selection of material has been discussed and promising materials identified. The feasibility of using flexible fin propellers for wave propulsion to absorb wave energy and convert it into propulsive thrust has been studied. A one-fifth scale model of a three quarter ton racing yacht with a flexible fin propeller model mounted at the stem was tested. At a low Froude number, there is a significant reduction in the motion response and in the required thrust around the resonance zone, where the encounter wave length is equal to the ship length. Rotary Foil Propeller A three bladed propeller model with high-aspect ratio blades was tested in forward and reverse directions and zero speed conditions. The experimental results on the performance of the model at forward speed have been compared to that predicted by Bose [1987] using multiple stream tube theory and discussed. Application of Oscillating Foil Propeller and General Conclusions The practical application of three oscillating foil propellers and economic studies of their operation have been studied and discussed. Three ship examples with the same Froude number but different in sizes and a high speed craft have been used in these studies. Three types of oscillating foil propeller are designed for each ship example. The required stem hull form and the driving mechanism have been discussed. The application of the flexible fin propeller in wave propulsion has been demonstrated. The natural frequency of a full scale flexible fin propeller was calculated and found to be much higher than the optimum driving frequencies in the operating condition. The net present value method has been applied in the economic studies where breakeven conditions, different interest rates, fluctuation of oil price, and different additional maintenance costs have been considered. The main conclusions of this research have been drawn up and are presented. Recommendation on the design of these propeller are also made

MOD-0A 200 kW wind turbine generator design and analysis report

The design, analysis, and initial performance of the MOD-OA 200 kW wind turbine generator at Clayton, NM is documented. The MOD-OA was designed and built to obtain operation and performance data and experience in utility environments. The project requirements, approach, system description, design requirements, design, analysis, system tests, installation, safety considerations, failure modes and effects analysis, data acquisition, and initial performance for the wind turbine are discussed. The design and analysis of the rotor, drive train, nacelle equipment, yaw drive mechanism and brake, tower, foundation, electricl system, and control systems are presented. The rotor includes the blades, hub, and pitch change mechanism. The drive train includes the low speed shaft, speed increaser, high speed shaft, and rotor brake. The electrical system includes the generator, switchgear, transformer, and utility connection. The control systems are the blade pitch, yaw, and generator control, and the safety system. Manual, automatic, and remote control are discussed. Systems analyses on dynamic loads and fatigue are presented

Aeronautical engineering: A special bibliography with indexes, supplement 82, April 1977

This bibliography lists 311 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1977

Research reports: 1991 NASA/ASEE Summer Faculty Fellowship Program

The basic objectives of the programs, which are in the 28th year of operation nationally, are: (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA Centers. The faculty fellows spent 10 weeks at MSFC engaged in a research project compatible with their interests and background and worked in collaboration with a NASA/MSFC colleague. This is a compilation of their research reports for summer 1991

Space Shuttle program communication and tracking systems interface analysis

The Space Shuttle Program Communications and Tracking Systems Interface Analysis began April 18, 1983. During this time, the shuttle communication and tracking systems began flight testing. Two areas of analysis documented were a result of observations made during flight tests. These analyses involved the Ku-band communication system. First, there was a detailed analysis of the interface between the solar max data format and the Ku-band communication system including the TDRSS ground station. The second analysis involving the Ku-band communication system was an analysis of the frequency lock loop of the Gunn oscillator used to generate the transmit frequency. The stability of the frequency lock loop was investigated and changes to the design were reviewed to alleviate the potential loss of data due the loop losing lock and entering the reacquisition mode. Other areas of investigation were the S-band antenna analysis and RF coverage analysis

Stage effects on stalling and recovery of a high-speed 10-stage axial-flow compressor

Results of a high-speed 10-stage axial-flow compressor test involving overall compressor and individual stage performance while stalling and operating in quasi-steady rotating stall are described. Test procedures and data acquisition methods used to obtain the dynamic stalling and quasi-steady in-stall data are explained. Unstalled and in-stall time-averaged data obtained from the compressor operating at five different shaft speeds and one off-schedule variable vane condition are presented. The effects of compressor speed and variable geometry on overall compressor in-stall pressure rise and hysteresis extent are illustrated through the use of quasi-steady stage temperature rise and pressure rise characteristics. The results indicate that individual stage performance during overall compressor rotating stall operation varies considerably throughout the length of the compressor. Time-resolved in-stall data acquired at two different shaft speeds are presented in support of the notion that stage operation varies significantly from entrance to exit of the compressor. Both time-averaged and time-resolved individual stage results suggest that stage matching is important, not only for unstalled performance but also for in-stall performance and recoverability from stall;The measured high-speed 10-stage test compressor individual stage pressure and temperature characteristics were input into a stage-by-stage dynamic compressor performance model. The analytical model had been previously validated for the prediction of low-speed compressor stalling and in-stall performance. Dynamic pressures measured during stalling of the high-speed 10-stage test compressor are compared with analytical model results. The comparison of the model results and the measured pressures provided the additional validation necessary to demonstrate the model\u27s ability to predict high-speed multistage compressor stalling and in-stall performance

Development of CAE tools for fluid-structure interaction and erosion in turbomachinery virtual prototyping

The work presented in this thesis is based on the development of advanced computer aided engineering tools dedicated to multi-physics coupled problems. Starting from the state of the art of numerical tools used in virtual prototyping and testing of turbomachinery systems, we found two interesting and actual possible developments focused on the improved implementation of fluid-structure interaction and material wearing solvers. For both the topics we will present a brief overview with the contextualization on the industrial and research state of the art, the detailed description of mathematical models (Chapter 2), discretized (FEM) stabilized formulations, time integration schemes and coupling algorithms used in the implementation (Chapter 3). The second part of the thesis (Chapter 4-7) will report some application of the developed tools on some latest challenges in turbomachinery field as rain erosion and load control in wind turbines and non-linear aeroelasticity in large axial fans

Centrifugally Stiffened Rotor: Eternal Flight as the Solution for 'X': NIAC Phase I Final Report

Flight has always captured man's imagination. This is evidenced by the great variety of aerial vehicles that exist today. Everything from fixed-wing to rotorcraft; satellites to spaceships;mono-wing to quadrotor. However, despite the wide variety of flying vehicles, not one of them has attained eternal flight. Accomplishing this feat is one of the great challenges still facing the aviation community. Motivation Achieving eternal flight opens the doors to atmospheric satellites. Existing satellites have a great number of capabilities that enrich our lives; however,their distance from the surface of the earth precludes certain types of transmission capabilities. Once eternal flight is achieved, that vehicle can serve the same role as ordinary satellites, but its close proximity will allow for real time two way communications,like wireless broadband internet. And with active controls, atmospheric satellites would not be constrained to geosynchronous orbits, like our existing satellite technology. Many projects are under way to achieve this goal;however, most of these research efforts follow the same design methodology, and have exhausted the limits of this particular design. This concept introduces a completely new aerial vehicle structure,which uses the best features of fixed-wing and rotorcraft designs. Combining the best features of different classes of aircraft, expands the capabilities beyond what either one can achieve on its own

Cumulative Index to NASA Tech Briefs, 1963 - 1966

Cumulative index of NASA Tech Briefs dealing with electrical and electronic, physical science and energy sources, materials and chemistry, life science, and mechanical innovation