Orbit Transfer Vehicle (OTV) advanced expander cycle engine point design study. Volume 2: Study results

Detailed computer models of the engine were developed to predict both the steady state and transient operation of the engine system. Mechanical design layout drawings were prepared for the following components: thrust chamber and nozzle; extendible nozzle actuating mechanism and seal; LOX turbopump and boost pump; hydrogen turbopump and boost pump; and the propellant control valves. The necessary heat transfer, stress, fluid flow, dynamic, and performance analyses were performed to support the mechanical design

Research and technology

The research and technology accomplishments of the NASA Lewis Research Center are summarized for the fiscal year 1986, the 45th anniversary year of the Center. Five major sections are presented covering: aeronautics, aerospace technology, space communications, space station systems, and computational technology support. A table of contents by subjects was developed to assist the reader in finding articles of special interest

Modeling and Control of Hydraulic Linear and Free-Piston Engines.

The EPA has developed a free-piston engine (FPE) and a hydraulic linear engine (HLE) for application as hydraulic power plants in a hydraulic hybrid vehicle. Both engines extract power from the piston motion using a linear hydraulic pump. This dissertation's objective is to compare HLE and FPE performance trends through modeling while developing the control tools necessary to enable reliable engine operation. A physics-based engine model combines dynamics, thermodynamics, and hydraulics correlations to evaluate performance trends and assist with control development. Preliminary simulations show that asymmetric piston behavior causes variations in cylinder-to-cylinder HLE efficiency that necessitate cylinder balancing. An adaptive control scheme estimates and adjusts for HLE cylinder performance discrepancies. A control-oriented model captures HLE behavior using an estimate of rotational kinetic energy sampled at the turnaround points. State feedback control ensures that the HLE tracks a set point and a recursive least squares algorithm estimates periodic differences in HLE response. An extremum seeking algorithm exploits the adaptive scheme to optimize injection timing of each cylinder individually. Precise control of piston turnaround location is paramount to reliable FPE operation. Combining an energy balance and the Otto cycle, a control-oriented model implicitly describes FPE clearance height evolution. A linearization of the control-oriented model suggests open-loop unstable operating conditions at high load. State feedback using dynamic inversion stabilizes the FPE system. In order to constrain piston motion, a reference governor manages load changes. When implemented on the physics-based model with the feedback control law, the reference governor successfully enforces a position constraint of 0.5 mm. Using the proposed control and modeling methods, a series of physics-based simulations explore HLE, FPE, and conventional engine performance. The primary difference in engine behavior is friction. While the FPE exhibits low frictional losses and the highest relative hydraulic conversion efficiency, it also suffers from a restricted power range compared to the HLE and the conventional engine due to engine speed limitations. The HLE has lower friction than the conventional engine at most operating conditions. However, inertial forces resulting from a large piston assembly mass increase HLE bearing loads and friction at high speeds.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/102345/1/kzaseck_1.pd

Line Fluid Actuated Valve Development Program

The feasibility of a line-fluid actuated valve design for potential application as a propellant-control valve on the space shuttle was examined. Design and analysis studies of two prototype valve units were conducted and demonstrated performance is reported. It was shown that the line-fluid actuated valve concept offers distinct weight and electrical advantages over alternate valve concepts. Summaries of projected performance and design goals are also included

Study of one-man lunar flying vehicle. Volume 3 - Subsystem studies Final report

Criteria for optimum design of lunar flying vehicl

The SIMPSONS project: An integrated Mars transportation system

In response to the Request for Proposal (RFP) for an integrated transportation system network for an advanced Martian base, Frontier Transportation Systems (FTS) presents the results of the SIMPSONS project (Systems Integration for Mars Planetary Surface Operations Networks). The following topics are included: the project background, vehicle design, future work, conclusions, management status, and cost breakdown. The project focuses solely on the surface-to-surface transportation at an advanced Martian base

COMBUSTION AND HEAT TRANSFER IN MESO-SCALE HEAT RECIRCULATING COMBUSTORS

Combustion in small-scale systems faces problems related to time available for chemical reaction to go to completion and the possible quenching of the reaction by the increased effects of interfacial phenomena (thermal quenching and radical quenching) that occur at the combustor walls due to higher surface to volume ratio. Heat recirculation, where in a portion of the energy from the products is fed back to the reactants through structural conduction is one of the strategies employed in meso-scale combustors to overcome the problems of thermal quenching of the flame. When liquid fuels are employed, structural conduction can help pre-vaporize the fuel and thereby removes the necessity for a fuel atomizer. This dissertation focuses on the design, development and operational characteristics of meso-scale combustors employing heat recirculation principle. Self-sustained combustion of propane-air and methanol-air flames were achieved in sub centimeter dimensions (32.6 mm3). The effects of design and operational parameters like wall thermal conductivity, heat exchanger size/channel length, combustion chamber geometry, equivalence ratio, Reynolds number, and external heat transfer (loss) coefficient on the combustor performance were investigated experimentally and numerically. The experimental procedure involved fabrication of combustors with different geometric features employing materials of different thermal conductivities and then obtaining their operating limits. Thermal performance with respect to various flow conditions was obtained by measuring the reactant preheating and exhaust gas temperatures using thermocouples. Numerical simulations were performed for both reacting and non-reacting flow cases to understand the heat transfer characteristics with respect to various design and operational conditions. Both experiments and numerical simulations revealed that wall thermal conductivity is one of the most important parameters for meso-scale combustor design. For typical meso-scale dimensions wall materials with minimal thermal conductivity (< 1W/m-K), especially ceramics would yield the best performance. Results showed that the most thermally efficient operating condition occurs for fuel lean cases at higher Reynolds numbers. Flame dynamics inside the combustor were investigated through high-speed imaging and flame acoustic spectrum mapping. Due to the small length scales involved, hydrodynamic instabilities have negligible effect on meso-scale combustion. Flame was observed to be extremely stable with negligible fluctuations. However, a significant amount of thermoacoustic phenomena is present within the combustion regime. Chemiluminescence imaging was employed to correctly map the flame zone inside the combustor

Research and technology

The NASA Lewis Research Center's research and technology accomplishments for fiscal year 1987 are summarized. It comprises approximately 100 short articles submitted by staff members of the technical directorates and is organized into four sections: aeronautics, aerospace technology (which includes space communications), space station systems, and computational support. A table of contents by subject was developed to assist the reader in finding articles of special interest

Research and Technology 1996

This report selectively summarizes the NASA Lewis Research Center's research and technology accomplishments for fiscal year 1996. It comprises 116 short articles submitted by the staff scientists and engineers. The report is organized into six major sections: Aeronautics, Aerospace Technology, Space Flight Systems, Engineering & Computational Support, Lewis Research Academy, and Technology Transfer. The diversity of topics attests to the breadth of research and technology being pursued and to the skill mix of the staff that makes it possible. This report is not intended to be a comprehensive summary of all research and technology work done over the past fiscal year

Bibliography of Lewis Research Center technical publications announced in 1986

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1986. All the publications were announced in the 1986 issues of Scientific and Technical Aerospace Reports (STAR) and/or International Aerospace Abstracts (IAA). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses