Framework for a space shuttle main engine health monitoring system

A framework developed for a health management system (HMS) which is directed at improving the safety of operation of the Space Shuttle Main Engine (SSME) is summarized. An emphasis was placed on near term technology through requirements to use existing SSME instrumentation and to demonstrate the HMS during SSME ground tests within five years. The HMS framework was developed through an analysis of SSME failure modes, fault detection algorithms, sensor technologies, and hardware architectures. A key feature of the HMS framework design is that a clear path from the ground test system to a flight HMS was maintained. Fault detection techniques based on time series, nonlinear regression, and clustering algorithms were developed and demonstrated on data from SSME ground test failures. The fault detection algorithms exhibited 100 percent detection of faults, had an extremely low false alarm rate, and were robust to sensor loss. These algorithms were incorporated into a hierarchical decision making strategy for overall assessment of SSME health. A preliminary design for a hardware architecture capable of supporting real time operation of the HMS functions was developed. Utilizing modular, commercial off-the-shelf components produced a reliable low cost design with the flexibility to incorporate advances in algorithm and sensor technology as they become available

Small business innovation research. Abstracts of completed 1987 phase 1 projects

Non-proprietary summaries of Phase 1 Small Business Innovation Research (SBIR) projects supported by NASA in the 1987 program year are given. Work in the areas of aeronautical propulsion, aerodynamics, acoustics, aircraft systems, materials and structures, teleoperators and robotics, computer sciences, information systems, spacecraft systems, spacecraft power supplies, spacecraft propulsion, bioastronautics, satellite communication, and space processing are covered

Civil Space Technology Initiative: a First Step

This is the first published overview of OAST's focused program, the Civil Space Technology Initiative, (CSTI) which started in FY88. This publication describes the goals, technical approach, current status, and plans for CSTI. Periodic updates are planned

NASA SBIR abstracts of 1991 phase 1 projects

The objectives of 301 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1991 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 301, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1991 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included

Civil space technology initiative

The Civil Space Technology Initiative (CSTI) is a major, focused, space technology program of the Office of Aeronautics, Exploration and Technology (OAET) of NASA. The program was initiated to advance technology beyond basic research in order to expand and enhance system and vehicle capabilities for near-term missions. CSTI takes critical technologies to the point at which a user can confidently incorporate the new or expanded capabilities into relatively near-term, high-priority NASA missions. In particular, the CSTI program emphasizes technologies necessary for reliable and efficient access to and operation in Earth orbit as well as for support of scientific missions from Earth orbit

Industrial Applications of Tunable Diode Laser Absorption Spectroscopy

Tunable diode laser absorption spectroscopy (TDLAS) utilizes the absorption phenomena to measure the temperature and species concentration. The main features of the TDLAS technique are its fast response and high sensitivity. Extensive research has been performed on the utilization of diode laser absorption spectroscopy for the system monitoring and its control. The TDLAS technique gives self-calibrations to reduce the noise such as particles and dusts because the laser wavelength is rapidly modulated at kHz rates. In addition, two dimensional (2D) temperature and concentration distributions can be obtained by combining computed tomography (CT) with TDLAS. The TDLAS applications have been extensively studied with great progress. This chapter largely focuses on the engineering fields, especially the practical industrial applications

Laser Diagnostic Techniques with Ultra-High Repetition Rate for Studies in Combustion Environments

When conducting laser based diagnostics in combustion environments it is often desirable to obtain temporally resolved information. This can be due to several factors such as combustion taking place in a turbulent flow field, flame propagation from a spark plug in an initially quiescent combustible mixture, or rapid, multi-point fuel consumption in a homogeneous charge as a result of compression ignition in an engine cycle. A multi-YAG laser cluster and a high-speed framing camera capable of recording sequences of up to eight image frames, and having a framing rate up to the megahertz range were originally set up for these types of studies. Within the framework of this thesis, further developments of this high-speed diagnostic system aiming at extending the wavelength palette and thus the range of detectable species, was carried out. In addition, the system was used for measurements with ultra-high repetition rates for the detection of different flame species in a variety of combustion devices. The high-speed laser system was redesigned for the generation of laser radiation at 355 nm, in addition to the original 532 nm and 266 nm, and a successful feasibility test for high-speed formaldehyde planar laser-induced fluorescence (PLIF) was carried out for the new design. Moreover, a novel multi-dye laser cluster has been set up. By pumping each of the four dye lasers individually using the Nd:YAG lasers in the multi-YAG cluster, tunable laser radiation with an ultra-high repetition rate can be produced, without the drawback of either losses in laser pulse energy or significant deterioration of the beam intensity profile often occurring when a single dye laser is pumped at ultra-high repetition rates. The multi-YAG and multi-dye laser clusters were used for high-speed visualization of the OH radical by means of planar laser-induced fluorescence in a low-swirl methane/air flame for tracking flame front movements over time while simultaneously measuring the flow-velocity field. Simultaneous high-speed OH visualization and imaging of the temperature field was also performed. The work carried out was a first step in the development of a detailed Large Eddy Simulation validation database for turbulent, premixed methane/air flames. High-speed OH PLIF using a single dye laser was employed in several other studies of the reaction zone, including an investigation of the ignition properties of hot jets in explosive environments, a study of combustion processes in a pulse combustor, and an investigation of the governing processes leading to electrical signals in an ion-current sensor. The last of these also included high-speed fuel tracer LIF. An alternative technique for flame studies involving measurement of the chemiluminescence from OH and CH in order to determine the equivalence ratio was investigated in terms of spatial and temporal resolution. The capability of the technique for resolving flame fronts was compared to reference measurements of OH PLIF. The tests showed that the spatial resolution in the depth direction suffered from line-of-sight detection, which significantly reduced the resolution. As the sensor was designed for monitoring spatial and temporal inhomogenities in mixtures within industrial gas turbine combustors, the temporal and spatial scales in such a combustor were evaluated using the high-speed laser diagnostic system for time-resolved visualization of OH. Also, fuel tracer PLIF was performed in order to visualize the fuel distribution in the combustor. The multi-YAG laser cluster was used in several studies of combustion processes in a homogeneous charge compression ignition (HCCI) engine, involving both high-speed fuel tracer PLIF and formaldehyde PLIF, with the aim of studying different types of ignition control. Acetone was used as a fuel tracer in investigating the effects of combustion chamber geometry on combustion. In studies of spark-assisted HCCI operation, the engine was run on a fuel mixture containing n-heptane, which produces formaldehyde early in the cool-flame region. Formaldehyde can thus be used as a fuel marker, eliminating the need of an added fuel tracer in this situation. Furthermore, three-dimensional imaging of formaldehyde in a laboratory flame as well as of Jet-A vapour in a slow non-reacting flow was demonstrated. This was achieved by rapidly scanning the laser sheet across a measurement volume spatially separating the eight laser pulses. A stack of closely spaced PLIF images was acquired by the framing camera, which could be used to re-create the three-dimensional shape of the investigated species by means of interpolation between the sheets

NASA SBIR abstracts of 1990 phase 1 projects

The research objectives of the 280 projects placed under contract in the National Aeronautics and Space Administration (NASA) 1990 Small Business Innovation Research (SBIR) Phase 1 program are described. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses in response to NASA's 1990 SBIR Phase 1 Program Solicitation. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 280, in order of its appearance in the body of the report. The document also includes Appendixes to provide additional information about the SBIR program and permit cross-reference in the 1990 Phase 1 projects by company name, location by state, principal investigator, NASA field center responsible for management of each project, and NASA contract number