Development of mainshaft seals for advanced air breathing propulsion systems, phase 2 Final report
Design and performance of gas-film and oil-film lubricated self sealing mainshaft seals for gas turbine engines
Mckibbin, A. H.↗
SEARCH · Engineering Papers
Results for “Self propulsion”
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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Transient flow thrust prediction for an ejector propulsion concept
A method for predicting transient thrust augmenting ejector characteristics is introduced. The analysis blends classic self-similar turbulent jet descriptions with a mixing region control volume analysis to predict transient effects in a new way. Details of the theoretical foundation, the solution algorithm, and sample calculations are given.
Drummond, Colin K.↗
Transient flow thrust prediction for an ejector propulsion concept
A method for predicting transient thrust augmenting ejector characteristics is introduced. The analysis blends classic self-similar turbulent jet descriptions with a mixing region control volume analysis to predict transient effects in a new way. Details of the theoretical foundation, the solution algorithm, and sample calculations are given.
Drummond, C.↗
Magnetoplasmadynamic thruster development
Current research on self-field MPD thrusters presents the possibility of developing high power/low cost electric propulsion. The interest generated in this propulsion concept within both NASA and the U.S. Air Force has led to a coordinated interagency effort, and the recent completion of several test sites are expected to speed thruster concept development. Efficiencies approaching 40% at 2200 sec have been experimentally demonstrated. Among the characteristics recommending development of MPD thrusters are high thrust density and power handling capability, simplicity, and a wide dynamic range of thrust and specific impulse. MPD thrusters can, moreover, operate either continuously, at high available power levels, or in a pulsed mode, to match lower power levels.
Pawlik, E. V.↗
Towards Integrated Pulse Detonation Propulsion and MHD Power
The interest in pulse detonation engines (PDE) arises primarily from the advantages that accrue from the significant combustion pressure rise that is developed in the detonation process. Conventional rocket engines, for example, must obtain all of their compression from the turbopumps, while the PDE provides additional compression in the combustor. Thus PDE's are expected to achieve higher I(sub sp) than conventional rocket engines and to require smaller turbopumps. The increase in I(sub sp) and the decrease in turbopump capacity must be traded off against each other. Additional advantages include the ability to vary thrust level by adjusting the firing rate rather than throttling the flow through injector elements. The common conclusion derived from these aggregated performance attributes is that PDEs should result in engines which are smaller, lower in cost, and lighter in weight than conventional engines. Unfortunately, the analysis of PDEs is highly complex due to their unsteady operation and non-ideal processes. Although the feasibility of the basic PDE concept has been proven in several experimental and theoretical efforts, the implied performance improvements have yet to be convincingly demonstrated. Also, there are certain developmental issues affecting the practical application of pulse detonation propulsion systems which are yet to be fully resolved. Practical detonation combustion engines, for example, require a repetitive cycle of charge induction, mixing, initiation/propagation of the detonation wave, and expulsion/scavenging of the combustion product gases. Clearly, the performance and power density of such a device depends upon the maximum rate at which this cycle can be successfully implemented. In addition, the electrical energy required for direct detonation initiation can be significant, and a means for direct electrical power production is needed to achieve self-sustained engine operation. This work addresses the technological issues associated with PDEs for integrated aerospace propulsion and MHD power. An effort is made to estimate the energy requirements for direct detonation initiation of potential fuel/oxidizer mixtures and to determine the electrical power requirements. This requirement is evaluated in terms of the possibility for MHD power generation using the combustion detonation wave. Small scale laboratory experiments were conducted using stoichiometric mixtures of acetylene and oxygen with an atomized spray of cesium hydroxide dissolved in alcohol as an ionization seed in the active MHD region. Time resolved thrust and MHD power generation measurements were performed. These results show that PDEs yield higher I(sub sp) levels than a comparable rocket engine and that MHD power generation is viable candidate for achieving self-excited engine operation.
Litchford, Ron J.↗
Technology programs and related policies - Impacts on communications satellite business ventures
The DOMSAT II stochastic communication satellite business venture financial planning simulation model is described. The specification of business scenarios and the results of several analyses are presented. In particular, the impacts of NASA on-orbit propulsion and power technology programs are described. The effects of insurance rates and self-insurance and of the use of the Space Shuttle and Ariane transportation systems on a typical fixed satellite service business venture are discussed.
Greenberg, J. S.↗
On Study of Air/Space-borne Dual-Wavelength Radar for Estimates of Rain Profiles
In this study, a framework is discussed to apply air/space-borne dual-wavelength radar for the estimation of characteristic parameters of hydrometeors. The focus of our study is on the Global Precipitation Measurements (GPM) precipitation radar, a dual-wavelength radar that operates at Ku (13.8 GHz) and Ka (35 GHz) bands. As the droplet size distributions (DSD) of rain are expressed as the Gamma function, a procedure is described to derive the median volume diameter (D(sub 0)) and particle number concentration (N(sub T)) of rain. The correspondences of an important quantity of dual-wavelength radar, defined as deferential frequency ratio (DFR), to the D(sub 0) in the melting region are given as a function of the distance from the 0 C isotherm. A self-consistent iterative algorithm that shows a promising to account for rain attenuation of radar and infer the DSD without use of surface reference technique (SRT) is examined by applying it to the apparent radar reflectivity profiles simulated from the DSD model and then comparing the estimates with the model (true) results. For light to moderate rain the self-consistent rain profiling approach converges to unique and correct solutions only if the same shape factors of Gamma functions are used both to generate and retrieve the rain profiles, but does not converges to the true solutions if the DSD form is not chosen correctly. To further examine the dual-wavelength techniques, the self-consistent algorithm, along with forward and backward rain profiling algorithms, is then applied to the measurements taken from the 2nd generation Precipitation Radar (PR-2) built by Jet Propulsion Laboratory. It is found that rain profiles estimated from the forward and backward approaches are not sensitive to shape factor of DSD Gamma distribution, but the self-consistent method is.
Liao, Liang↗
Sensor Needs for Control and Health Management of Intelligent Aircraft Engines
NASA and the U.S. Department of Defense are conducting programs which support the future vision of "intelligent" aircraft engines for enhancing the affordability, performance, operability, safety, and reliability of aircraft propulsion systems. Intelligent engines will have advanced control and health management capabilities enabling these engines to be self-diagnostic, self-prognostic, and adaptive to optimize performance based upon the current condition of the engine or the current mission of the vehicle. Sensors are a critical technology necessary to enable the intelligent engine vision as they are relied upon to accurately collect the data required for engine control and health management. This paper reviews the anticipated sensor requirements to support the future vision of intelligent engines from a control and health management perspective. Propulsion control and health management technologies are discussed in the broad areas of active component controls, propulsion health management and distributed controls. In each of these three areas individual technologies will be described, input parameters necessary for control feedback or health management will be discussed, and sensor performance specifications for measuring these parameters will be summarized.
Simon, Donald L.↗
Model-Based Control of a Nonlinear Aircraft Engine Simulation using an Optimal Tuner Kalman Filter Approach
This paper covers the development of a model-based engine control (MBEC) methodology featuring a self tuning on-board model applied to an aircraft turbofan engine simulation. Here, the Commercial Modular Aero-Propulsion System Simulation 40,000 (CMAPSS40k) serves as the MBEC application engine. CMAPSS40k is capable of modeling realistic engine performance, allowing for a verification of the MBEC over a wide range of operating points. The on-board model is a piece-wise linear model derived from CMAPSS40k and updated using an optimal tuner Kalman Filter (OTKF) estimation routine, which enables the on-board model to self-tune to account for engine performance variations. The focus here is on developing a methodology for MBEC with direct control of estimated parameters of interest such as thrust and stall margins. Investigations using the MBEC to provide a stall margin limit for the controller protection logic are presented that could provide benefits over a simple acceleration schedule that is currently used in traditional engine control architectures.
Control Theory↗
High Power Thruster Based on Inductive Magnetized Plasmoid Acceleration
Regardless of the power source, deep space missions will require both high specific impulse (greater than 500 s) and high thrust power (greater than 100kW). These high Isp thrusters will need to have high electrical efficiency (approx. 90%) and low specific mass (alpha approximately less than 10 kg/kW) as well. Additionally they should have high thrust to allow greater mission flexibility. All these requirements can potentially be achieved with the pulsed formation and acceleration of magnetically self-confined plasmoids commonly referred to as compact toroids (CTs). An electromagnetic plasma thruster based on CT acceleration makes an ideal candidate for a high power, high Isp thruster, since the CT is magnetically isolated from the accelerator so that there is no contact between the propellant and the accelerator. The transfer of momentum to the CT occurs through an electromagnetic interaction with the magnetic field. By maintaining an axial magnetic field gradient across it, the directed velocity of the CT can be increased indefinitely. In previous experiments carried out at the University of Washington, CT's of near milligram mass were accelerated to velocities of 250 km/s in a single pulse. The ejection of the plasmoid by an external axial field also avoids the serious problem of detachment, which would occur in thrusters that employ a magnetic mirror or magnetic nozzle. To employ the CT for propulsion, one must design, construct and test a plasma source that is capable of generating a self-confined plasma inductively, and to do it repeatedly at a sufficiently high rep rate. A repetitively pulsed 100 kW level FRC thruster was built and was operated for short bursts at a 10 kHz rep rate and will be described. Another regime for the FRC thruster however is to produce an FRC in a more conventional manner at high voltage and magnetic field. With the large energy transfer with each pulse, the rep rate for this approach is much lower (approximately 100 Hz). This is the approach that is being evaluated at MSFC in the FAST experiment. The purpose of this experiment is to build an FRC thruster, measure its performance characteristics e.g. specific impulse, thrust, and efficiency. This experiment will also be described as well as various mission scenarios that that are well matched for this type of propulsion.
Slough, John↗
Probing surface-adsorbate interactions through active particle dynamics
Adsorbate molecules present in a reaction mixture may bind to and block catalytic sites. Measurement of the surface coverage of these molecules via adsorption isotherms is critical for modeling and design of catalytic reactions on surfaces. However, it is challenging to measure isotherms in solution in a way that is directly relevant to catalytic activity under reaction conditions, particularly since adsorbates may bind with an enormous range of surface affinity parameters. Here we used the motion of self-propelled catalytic Janus particles, which employ the decomposition of hydrogen peroxide fuel as a propulsion mechanism, to determine the effective surface coverage of thioglycerol, furfural, and ethanol on a platinum surface as a function of concentration in aqueous solution by measuring the decrease in active motion due to the blocking of active sites. For strongly adsorbing thioglycerol, this effective coverage was compared and contrasted to the total adsorbed amount measured using inductively-coupled plasma analysis. Demonstrating the broad applicability of this approach, the surface affinity of the three adsorbates spanned more than four orders of magnitude. For each species, the adsorbate-mediated attenuation of active motion occurred over a wide concentration range and was well-described by a Langmuir isotherm. The strongly interacting thioglycerol had the highest affinity towards the surface (K a = 15.5 ± 4.3 mM –1 ) and fully deactivated the active particle motion at surface saturation. Furfural had an intermediate affinity (K a = 0.42 ± 0.07 mM –1 ) but did not fully block H 2 O 2 access to the surface at apparent saturation, consistent with a maximum fractional surface coverage of θ max = 0.67. Ethanol exhibited even lower affinity (K a = 0.0025 ± 2x10 -4 mM –1 ) and its coverage saturated at only θ max = 0.38. Analysis of isotherms at elevated temperatures enabled direct extraction of the enthalpies of adsorption. The degree of surface coverage at adsorbate saturation appeared to correlate with the relative energies of adsorption for the different adsorbate species and was consistent with adsorbate saturation of one of multiple active site populations towards H 2 O 2 decomposition. Furthermore, computational investigations into solvent effects on furfural adsorption showed good quantitative agreement with the experimental results. This work leverages unique properties of active particles to explore fundamental catalysis questions and demonstrates a novel paradigm for significant and experimentally accessible multidisciplinary research.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Conference on Advanced Technology for Future Space Systems, Hampton, Va., May 8-10, 1979, Technical Papers
Propulsion systems for spacecraft, satellite communications technology, the design of large light-weight erectable structures for assembly in space, electronics and information processing for spacecraft, and self-diagnostic, fault-tolerant controls based on high memory and processing capabilities are discussed. Topics of the papers include the design of large delta wings for earth-to-orbit transports, dual-fuel propulsion units, magnetoplasmadynamic thrusters, heating rates on blunt-nosed bodies at various angles of attack, remote manipulators for space assembly tasks, solar electric propulsion for planetary missions, deployable space platforms with multiple payloads, the design of large offset-fed antennas, a nonlinear stress-strain relationship for metallic meshes, and adaptive sensors for spacecraft.
Source record↗
Communications satellite business ventures - Measuring the impact of technology programmes and related policies
An economic evaluation and planning procedure which assesses the effects of various policies on fixed satellite business ventures is described. The procedure is based on a stochastic financial simulation model, the Domsat II, which evaluates spacecraft reliability, market performance, and cost uncertainties. The application of the Domsat II model to the assessment of NASA's ion thrusters for on-orbit propulsion and GaAs solar cell technology is discussed. The effects of insurance rates and the self-insurance option on the financial performance of communication satellite business ventures are investigated. The selection of a transportation system for placing the satellites into GEO is analyzed.
Greenberg, J. S.↗
The Moon as a way station for planetary exploration
The Moon can be on the pathway to the exploration of other planets in the solar system in three distinct ways: science, systems and technology experience, and as a fuel depot. The most important of these from the point of view of near term potential is to provide systems and technology development that increases capability and reduces the cost and risk of Mars exploration. The development of capability for a lunar program, if planned properly, can significantly influence strategies for sending humans to Mars. In conclusion, the exploration of the Moon should come before the exploration of Mars. This is a statement of developmental and operational logic that is almost self evident. Technological advancement could, however, make a different strategy reasonable. Principally, the development of a propulsion capability that could substantially reduce round trip mission times to Mars (to say 6 to 12 months) could eliminate much of the argument that the Moon is an essential stepping stone. This would reduce the problem to one of similitude with current space station program concepts. However, for any reasonably near term program, such technology does not appear likely to be available. Thus, the answer remains that lunar exploration should come first, and the expectation that it will make Mars exploration much more affordable and safe. The use of lunar propellant in an Earth-Mars transportation system is not practical with current propulsion systems; however, the discovery of caches of water ice at a lunar pole could change considerably the strategy for utilization of lunar resources in planetary exploration.
Duke, M. B.↗
Exhaust flow and propulsion characteristics of a pulsed MPD arc thruster.
Experimental investigation of the near-field, megawatt, single-shot exhaust for the self-field and auxiliary field cases (0 to 2 tesla) for a pulsed MPD arc thrustor. Plasma impact pressure and number density are correlated to provide velocity profiles (30,000 to 70,000 m/sec), thrust (10 to 120 N), impulse (3 to 16 N-sec) and mass accounting. The data agree with Hugel's self-field theory for the case where thrust is produced entirely by electromagnetic force. The data show that the thrust monotonically increases with auxiliary field.
Michels, C. J.↗
Benchmarking Model Variants in Development of a Hardware-in-the-Loop Simulation System
Distributed engine control architecture presents a significant increase in complexity over traditional implementations when viewed from the perspective of system simulation and hardware design and test. Even if the overall function of the control scheme remains the same, the hardware implementation can have a significant effect on the overall system performance due to differences in the creation and flow of data between control elements. A Hardware-in-the-Loop (HIL) simulation system is under development at NASA Glenn Research Center that enables the exploration of these hardware dependent issues. The system is based on, but not limited to, the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k). This paper describes the step-by-step conversion from the self-contained baseline model to the hardware in the loop model, and the validation of each step. As the control model hardware fidelity was improved during HIL system development, benchmarking simulations were performed to verify that engine system performance characteristics remained the same. The results demonstrate the goal of the effort; the new HIL configurations have similar functionality and performance compared to the baseline C-MAPSS40k system.
Networked Systems↗
Benchmarking Model Variants in Development of a Hardware-in-the-Loop Simulation System
Distributed engine control architecture presents a significant increase in complexity over traditional implementations when viewed from the perspective of system simulation and hardware design and test. Even if the overall function of the control scheme remains the same, the hardware implementation can have a significant effect on the overall system performance due to differences in the creation and flow of data between control elements. A Hardware-in-the-Loop (HIL) simulation system is under development at NASA Glenn Research Center that enables the exploration of these hardware dependent issues. The system is based on, but not limited to, the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k). This paper describes the step-by-step conversion from the self-contained baseline model to the hardware in the loop model, and the validation of each step. As the control model hardware fidelity was improved during HIL system development, benchmarking simulations were performed to verify that engine system performance characteristics remained the same. The results demonstrate the goal of the effort; the new HIL configurations have similar functionality and performance compared to the baseline C-MAPSS40k system.
Propulsion Simulation↗
Structures Self-Assembled Through Directional Solidification
Nanotechnology has created a demand for new fabrication methods with an emphasis on simple, low-cost techniques. Directional solidification of eutectics (DSE) is an unconventional approach in comparison to low-temperature biomimetic approaches. A technical challenge for DSE is producing microstructural architectures on the nanometer scale. In both processes, the driving force is the minimization of Gibb's free energy. Selfassembly by biomimetic approaches depends on weak interaction forces between organic molecules to define the architectural structure. The architectural structure for solidification depends on strong chemical bonding between atoms. Constituents partition into atomic-level arrangements at the liquid-solid interface to form polyphase structures, and this atomic-level arrangement at the liquid-solid interface is controlled by atomic diffusion and total undercooling due to composition (diffusion), kinetics, and curvature of the boundary phases. Judicious selection of the materials system and control of the total undercooling are the keys to producing structures on the nanometer scale. The silicon-titanium silicide (Si-TiSi2) eutectic forms a rod structure under isothermal cooling conditions. At the NASA Glenn Research Center, directional solidification was employed along with a thermal gradient to promote uniform rods oriented with the thermal gradient. The preceding photomicrograph shows the typical transverse microstructure of a solidified Si-TiSi2 eutectic composition. The dark and light gray regions are Si and TiSi2, respectively. Preferred rod orientation along the thermal gradient was poor. The ordered TiSi2 rods have a narrow distribution in diameter of 2 to 3 m, as shown. The rod diameter showed a weak dependence on process conditions. Anisotropic etch behavior between different phases provides the opportunity to fabricate structures with high aspect ratios. The photomicrographs show the resulting microstructure after a wet chemical etch and a dry plasma etch. The wet chemical etches the silicon away, exposing the TiSi2 rods, whereas plasma etching preferentially etches the Si-TiSi2 interface to form a crater. The porous architectures are applicable to fabricating microdevices or creating templates for part fabrication. The porous rod structure can serve as a platform for fabricating microplasma devices for propulsion or microheat exchangers and for fabricating microfilters for miniatured chemical reactors. Although more work is required, self-assembly from DSE can have a role in microdevice fabrication.
Dynys, Frederick W.↗