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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Numerical thermal analyses that contributed to the elimination of turbine blade firtree cracks in the Space Shuttle Main Engine High Pressure Fuel Turbopump turbine

NASA-Marshall has undertaken analytical and experimental efforts to eliminate all turbine blade cracking and further improve the safety and reliability of the SSME. This work is focused on the elimination of cracks at the blade firtree attachment to the disk, in both the first- and second-stage rotors of the High Pressure Fuel Turbopump. Emphasis is placed on thermal analyses that preceded the overall structural evaluation of the blade firtrees. Thermally-induced contributions to the stresses and strains in the firtrees were quantified by these studies, and feasible design improvement options were identified and tested.

Principe, R. S.↗
NASA NTRS1988

Laser velocimeter measurements of the flow downstream of the Space Shuttle Main Engine high pressure oxidizer turbopump first-stage turbine nozzle

A laser two-focus velocimeter was used in an open-loop water test facility in order to map the flowfield downstream of the SSME's high-pressure oxidizer turbopump first-stage turbine nozzle; attention was given to the effects of the upstream strut-downstream nozzle configuration on the flow at the rotor inlet, in order to estimate dynamic loads on the first-stage rotor blades. Velocity and flow angles were plotted as a function of circumferential position, and were found to clearly display the periodic behavior of the wake flow field. The influence of the upstream centerbody-supporting struts on the vane nozzle wake pattern was evident.

Ferguson, T. V.↗
NASA NTRS1988

Space shuttle main engine numerical modeling code modifications and analysis

The user of computational fluid dynamics (CFD) codes must be concerned with the accuracy and efficiency of the codes if they are to be used for timely design and analysis of complicated three-dimensional fluid flow configurations. A brief discussion of how accuracy and efficiency effect the CFD solution process is given. A more detailed discussion of how efficiency can be enhanced by using a few Cray Research Inc. utilities to address vectorization is presented and these utilities are applied to a three-dimensional Navier-Stokes CFD code (INS3D).

Ziebarth, John P.↗
NASA NTRS1989

Space Shuttle Main Engine structural analysis and data reduction/evaluation. Volume 1: Aft Skirt analysis

Using the ANSYS finite element program, a global model of the aft skirt and a detailed nonlinear model of the failure region was made. The analysis confirmed the area of failure in both STA-2B and STA-3 tests as the forging heat affected zone (HAZ) at the aft ring centerline. The highest hoop strain in the HAZ occurs in this area. However, the analysis does not predict failure as defined by ultimate elongation of the material equal to 3.5 percent total strain. The analysis correlates well with the strain gage data from both the Wyle influence test of the original design aft sjirt and the STA-3 test of the redesigned aft skirt. it is suggested that the sensitivity of the failure area material strength and stress/strain state to material properties and therefore to small manufacturing or processing variables is the most likely cause of failure below the expected material ultimate properties.

Berry, David M.↗
NASA NTRS1990

Object oriented fault diagnosis system for space shuttle main engine redlines

A great deal of attention has recently been given to Artificial Intelligence research in the area of computer aided diagnostics. Due to the dynamic and complex nature of space shuttle red-line parameters, a research effort is under way to develop a real time diagnostic tool that will employ historical and engineering rulebases as well as a sensor validity checking. The capability of AI software development tools (KEE and G2) will be explored by applying object oriented programming techniques in accomplishing the diagnostic evaluation.

Rogers, John S.↗
NASA NTRS1989

Manufacturing implementation of off-line programming for the Space Shuttle Main Engines

An account is given of the efforts made to implement an off-line programming (OLP) system for a gas tungsten arc welding robot in actual manufacturing operations, namely those involved in the manufacture of the SSMEs. In conjunction with a real-time sensor control system, the OLP constitutes the Advanced Robotic Welding System, or 'AROWS'. OLP's task is to develop a robot-motion path without the initial use of the robot to 'teach' the characteristics of such motion; actual process parameters are recorded by OLP and correlated with the position along the weld.

Sliwinski, K. E.↗
NASA NTRS1989

Finite element analysis of the Space Shuttle Main Engine (SSME) high pressure fuel turbopump turbine blade (HPFTP)

Cracking of the turbine blades of the SSME HPFTP is studied using two- and three-dimensional finite element analysis. The development and composition of the two- and three-dimensional models are described. Analyses are conducted under the speed, pressure, and thermal load conditions that occur during the full power level of the engine. The effects of friction on the two-dimensional model are examined. The strain and life cycle data reveal that the LCF cracking in the first stage is not probable unless the effects of fit-up tolerance between the blade and rotor are present, and for the second stage it is predicted that hydrogen assisted LCF cracking will occur under the present thermal environment. Design modifications to alleviate this cracking are discussed.

Lee, H. M.↗
NASA NTRS1990

An expert system for fault diagnosis in a Space Shuttle main engine

The detection and diagnosis of SSME faults in an early stage is important in order to allow enough time for fault preventive or corrective measurements. Since most of the faults in a complex system like SSME develop rapidly, early detection and diagnosis of faults is critical for the survival of space vehicles. An expert system has been designed for automatic learning, detection, identification, verification, and correction of anomalous propulsion system operations. This paper describes an innovative machine learning approach which is employed for the automatic training of this expert system.

Ali, Moonis↗
NASA NTRS1989

Space Shuttle Main Engine component assembly, assignment, and scheduling expert system

The SSME's Component Assembly and Life Management Expert System (CALMES) assists the engine assembly and scheduling process, ensuring that these activities utilize available resources with the greatest possible efficiency. On the basis of parts inventories and a proposed flight schedule, CALMES (1) determined how components may be optimally assembled from the parts inventory, (2) assigns components to flights, (3) schedules component testing, and (4) schedules component assembly. A graph-theoretical optimal matching algorithm, based on a modified simplex method, is applied to the major functions required by the SSME component assembly and scheduling processes.

Dietz, W. E.↗
NASA NTRS1991

Space shuttle with common fuel tank for liquid rocket booster and main engines (supertanker space shuttle)

An operation and schedule enhancement is shown that replaces the four-body cluster (Space Shuttle Orbiter (SSO), external tank, and two solid rocket boosters) with a simpler two-body cluster (SSO and liquid rocket booster/external tank). At staging velocity, the booster unit (liquid-fueled booster engines and vehicle support structure) is jettisoned while the remaining SSO and supertank continues on to orbit. The simpler two-bodied cluster reduces the processing and stack time until SSO mate from 57 days (for the solid rocket booster) to 20 days (for the liquid rocket booster). The areas in which liquid booster systems are superior to solid rocket boosters are discussed. Alternative and future generation vehicles are reviewed to reveal greater performance and operations enhancements with more modifications to the current methods of propulsion design philosophy, e.g., combined cycle engines, and concentric propellant tanks.

Thorpe, Douglas G.↗
NASA NTRS1991

Space shuttle main engine: Certification for manned space flight

SSME requirements were identified in NASA approved documents. Design verification specifications (DVS) are used to define requirements and method of verification. Detailed and complete plans provide for verification of each requirement by lab tests, component tests, and engine tests. These tests are planned to expose problems early. The culmination of the development process is engine certification. The certification consists of two certification cycles on each of two engines. The certification cycle is made up of 10 tests and 5000 seconds.

Weesner, Ronald G.↗
NASA NTRS1990

Space Shuttle main engine technology and enhancements

The SSME Project Office is taking several paths to meet future needs for the Shuttle system. The producibility program focuses on manufacturing concerns. The product improvement program is attempting to address and correct limitations. The Alternate Turbopump Development Program focuses on the development of a more advanced and reliable turbopump design, and the Technology Test Bed Program focuses on the demonstration and verification of new technology and initial concept verification. A program has been structured to meet the needs of the payload community and to look forward toward the incorporation of advanced fabrication concepts.

Smelser, Jerry W.↗
NASA NTRS1991

Dynamic Characteristics and Stability Analysis of Space Shuttle Main Engine Oxygen Pump

The dynamic characteristics of the Space Shuttle high pressure oxygen pump are presented. Experimental data is presented to show the vibration spectrum and response under actual engine operation and also in spin pit testing for balancing. The oxygen pump appears to be operating near a second critical speed and is sensitive to self excited aerodynamic cross coupling forces in the turbine and pump. An analysis is presented to show the improvement in pump stability by the application of turbulent flow seals, preburner seals, and pump shaft cross sectional modifications.

Gunter, Edgar J.↗
NASA NTRS1992

Variable gamma computations for a forward-firing Space Shuttle Main Engine

A procedure for solving an axisymmetric SSME nozzle exhausting with an equivalent mass flow of two nozzles is presented for the return-to-launch-site (RTLS) maneuver for an engine-out case. The algorithm incorporates a two-species variable gamma formulation along with diffusion terms associated with a species conservation equation. Coupling of this algorithm is accomplished explicitly to the Navier-Stokes PARC2DR and PARC3DR codes. Axisymmetric results indicate a very complicated flowfield with a bow shock extending to approximately 570 radii in front of the nozzle, and low temperatures on what would be an external tank (ET) aft of the nozzle.

Saladino, A. J.↗