Engineering topics

Boyd, W. C.

Publications and source records attributed to Boyd, W. C..

5 records

NASA NTRS1990

Uprated OMS Engine Status-Sea Level Testing Results

The current Space Shuttle Orbital Maneuvering Engine (OME) is pressure fed, utilizing storable propellants. Performance uprating of this engine, through the use of a gas generator driven turbopump to increase operating pressure, is being pursued by the NASA Johnson Space Center (JSC). Component level design, fabrication, and test activities for this engine system have been on-going since 1984. More recently, a complete engine designated the Integrated Component Test Bed (ICTB), was tested at sea level conditions by Aerojet. A description of the test hardware and results of the sea level test program are presented. These results, which include the test condition operating envelope and projected performance at altitude conditions, confirm the capability of the selected Uprated OME (UOME) configuration to meet or exceed performance and operational requirements. Engine flexibility, demonstrated through testing at two different operational mixture ratios, along with a summary of projected Space Shuttle performance enhancements using the UOME, are discussed. Planned future activities, including ICTB tests at simulated altitude conditions, and recommendations for further engine development, are also discussed.

Bertolino, J. D.↗

NASA NTRS1986

Uprated OMS engine status and future applications

The baseline Orbital Maneuvering Engine (OME) of the Space Shuttle has the potential for significant performance uprating, leading to increased Shuttle performance capability. The approach to uprating that is being pursued at the NASA Lyndon B. Johnson Space Center is the use of a gas generator-driven turbopump to increase OME operating pressure. A higher pressure engine can have a greater nozzle expansion ratio in the same envelope and at the same thrust level, giving increased engine Isp. The results of trade studies and analyses that have led to the preferred uprated OME configuration are described. The significant accomplishments of a pre-development component demonstration program are also presented, including descriptions of test hardware and discussion of test results. It is shown that testing to date confirms the capability of the preferred uprated OME configuration to meet or exceed performance and life requirements. Potential future activities leading up to a full-scale development program are described, and the capability for the uprated OME to be used in future storable propellant upper stages is discussed.

Boyd, W. C.↗

NASA NTRS1984

Supercritical convection, critical heat flux, and coking characteristics of propane

The heat transfer characteristics of propane at subcritical and supercritical pressure were experimentally evaluated using electrically heated Monel K-500 tubes. A design correlation for supercritical heat transfer coefficient was established using the approach previously applied to supercritical oxygen. Flow oscillations were observed and the onset of these oscillations at supercritical pressures was correlated with wall-to-bulk temperature ratio and velocity. The critical heat flux measured at subcritical pressure was correlated with the product of velocity and subcooling. Long duration tests at fixed heat flux conditions were conducted to evaluate coking on the coolant side tube wall and coking rates comparable to RP-1 were observed.

Rousar, D. C.↗

NASA NTRS1984

Ignition characterization of the GOX/ethanol propellant combination

This paper describes the results of a study to define the ignition characteristics and thruster pulse mode capabilities of the GOX/ethanol propellant combination. Ignition limits were defined in terms of mixture ratio and cold flow pressure using a spark initiated torch igniter. Igniter tests were run over a wide range of cold flow pressure, propellant temperature and mixture ratio. The product of cold flow pressure and igniter chamber diameter was used to correlate mixture ratio regimes of ignition and nonignition. Engine ignition reliability and pulse mode capability were demonstrated using a 620 lbF thruster with an integrated torch igniter. The nominal chamber pressure and mixture ratio were 150 psia and 1.8, respectively, thruster tests were run over a wide range of chamber pressures and mixture ratios. The feasibility of thruster pulse mode operation with the non-hypergolic GOX/ethanol propellant combination was demonstrated.

Lawver, B. R.↗

NASA NTRS1984

Lox/hydrocarbon propellants for space propulsion systems

The significant results of technology efforts directed by the NASA Lyndon B. Johnson Space Center investigating liquid oxygen/hydrocarbon (lox/HC) propellant combination are presented. These efforts are intended to identify viable propellant combinations and system designs to replace nitrogen tetroxide and monomethylhydrazine for future spacecraft orbital maneuvering and attitude control systems, and to date have been focused primarily on the various technology areas of lox/HC combustion - injector element design effects, performance, combustion chamber heat transfer, coking, and ignition. In addition, a study was performed to compare candidate lox/HC propulsion system concepts and to evaluate major system/component design options. The data generated provide quantitative substantiation of trends previously experienced with hypergolic propellants and with a lox and rocket propellant combination. More importantly, however, the data provide a sound footing for the technology data base that must be built to support future systems development.

Boyd, W. C.↗