ASRC Aerospace Corporation

About: ASRC Aerospace Corporation is a based out in . It is known for research contribution in the topics: In situ resource utilization & Propulsion. The organization has 194 authors who have published 404 publications receiving 4748 citations.

Operability of an Ejector Enhanced Pulse Combustor in a Gas Turbine Environment

Abstract: A pressure-gain combustor comprised of a mechanically valved, liquid fueled pulsejet, an ejector, and an enclosing shroud, was coupled to a small automotive turbocharger to form a self-aspirating, thrust producing gas turbine engine. The system was constructed in order to investigate issues associated with the interaction of pulsed combustion devices and turbomachinery. Installed instrumentation allowed for sensing of distributed low frequency pressure and temperature, high frequency pressure in the shroud, fuel flow rate, rotational speed, thrust, and laboratory noise. The engine ran successfully and reliably, achieving a sustained thrust of 5 to 6 lbf, and maintaining a rotor speed of approximately 90,000 rpm, with a combustor pressure gain of approximately 4 percent. Numerical simulations of the system without pressure-gain combustion indicated that the turbocharger would not operate. Thus, the new combustor represented a substantial improvement in system performance. Acoustic measurements in the shroud and laboratory indicated turbine stage sound pressure level attenuation of 20 dB. This is consistent with published results from detonative combustion experiments. As expected, the mechanical reed valves suffered considerable damage under the higher pressure and thermal loading characteristics of this system. This result underscores the need for development of more robust valve systems for this application. The efficiency of the turbomachinery components did not appear to be significantly affected by unsteadiness associated with pulsed combustion, though the steady component efficiencies were already low, and thus not expected to be particularly sensitive.

Comparative Oxidation Kinetics of a NiPtTi High Temperature Shape Memory Alloy

Abstract: A high temperature shape memory alloy, Ni–30Pt–50Ti (at.%), with an M s near 600 °C, was isothermally oxidized in air for 100 h over the temperature range of 500–900 °C. Nearly parabolic kinetics were observed in log–log and parabolic plots, with no indication of initial fast transient oxidation. On average the rates were about a factor of 4 lower than values measured here for a binary Ni–49Ti commercial SMA. The overall behavior could be best described by the Arrhenius relationships: $${\text{Ni}}{\text{Pt}}{\text{Ti}}{:}\,k_{\text{p}} = 1.54 \times 10^{12} \exp \left[(- 250\,{\text{kJ}}/{\text{mol}}) {RT} \right]{\text{mg}}^{2}/{\text{cm}}^{4} {\text{h}} $$ $${\text{Ni}}{\text{Ti}}{:}\,k_{\text{p}} = 6.39 \times 10^{12} \exp \left[(- 249\,{\text{kJ}}/{\text{mol}}) {RT} \right]{\text{mg}}^{2}/{\text{cm}}^{4} {\text{h}} $$ The activation energy was consistent with literature values for TiO2 scale growth measured for elemental Ti and some NiTi alloys, at ~210–260 kJ/mol. However, a number of other studies produced activation energies in the range of 135–150 kJ/mol. This divergence may be related to various complex scale layers and depletion zones, however, no specific correlation can be identified at present.

Addressing Machining Issues for the Intermetallic Compound 60-NITINOL

Abstract: 60-NITINOL (60 wt.% Ni - 40 wt.% Ti) is being studied as a material for advanced aerospace components. Frequent wire breakage during electrical-discharge machining of this material was investigated. The studied material was fabricated from hot isostatically pressed 60-NITINOL powder obtained through a commercial source. Bulk chemical analysis of the material showed that the composition was nominal but had relatively high levels of certain impurities, including Al and O. It was later determined that Al2O3 particles had contaminated the material during the hot isostatic pressing procedure and that these particles were the most likely cause of the wire breakage. The results of this investigation highlight the importance of material cleanliness to its further implementation.

Engine Icing Modeling and Simulation (Part 2): Performance Simulation of Engine Rollback Phenomena

Abstract: Ice buildup in the compressor section of a commercial aircraft gas turbine engine can cause a number of engine failures. One of these failure modes is known as engine rollback: an uncommanded decrease in thrust accompanied by a decrease in fan speed and an increase in turbine temperature. This paper describes the development of a model which simulates the system level impact of engine icing using the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k). When an ice blockage is added to C-MAPSS40k, the control system responds in a manner similar to that of an actual engine, and, in cases with severe blockage, an engine rollback is observed. Using this capability to simulate engine rollback, a proof-of-concept detection scheme is developed and tested using only typical engine sensors. This paper concludes that the engine control system s limit protection is the proximate cause of iced engine rollback and that the controller can detect the buildup of ice particles in the compressor section. This work serves as a feasibility study for continued research into the detection and mitigation of engine rollback using the propulsion control system.

Neutralizer hollow cathode simulations and comparisons with ground test data

Abstract: The fidelity of electric propulsion physics-based models depends largely on the validity of their predictions over a range of operating conditions and geometries. In general, increased complexity of the physics requires more extensive comparisons with laboratory data to identify the region(s) that lie outside the validity of the model assumptions and to quantify the uncertainties within its range of application. This paper presents numerical simulations of neutralizer hollow cathodes at various operating conditions and orifice sizes. The simulations were performed using a two-dimensional axisymmetric model that solves numerically a relatively extensive system of conservation laws for the partially ionized gas in these devices. A summary of the comparisons between simulation results and Langmuir probe measurements is provided. The model has also been employed to provide insight into recent ground test observations of the neutralizer cathode in NEXT. It is found that a likely cause of the observed keeper voltage drop is cathode orifice erosion. However, due to the small magnitude of this change, is approx. 0.5 V (less than 5% of the beginning-of-life value) over 10 khrs, and in light of the large uncertainties of the cathode material sputtering yield at low ion energies, other causes cannot be excluded. Preliminary simulations to understand transition to plume mode suggest that in the range of 3-5 sccm the existing 2-D model reproduces fairly well the rise of the keeper voltage in the NEXT neutralizer as observed in the laboratory. At lower flow rates the simulation produces oscillations in the keeper current and voltage that require prohibitively small time-steps to resolve with the existing algorithms.