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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Single Degree-of-Freedom Modeling of SLS Liquid Hydrogen Pre-Valve Flow Guide to Enable Rapid Transient Analysis

A unique single degree-of-freedom approximation technique has been developed to enable rapid application of a temporally-defined multi-spectral semi-narrow-band loading for generation of realistic stress/cycle values compared to a resonant analysis. The technique uses the harmonic analysis at resonance of a high-fidelity finite element model to produce a transfer function, which is then used to calibrate the response of the SDOF model. A standard numerical ordinary differential equation solver is then used to obtain the temporal response, and its histogram is used in a fatigue/fracture model. This technique is related to other SDOF methods used widely in industry, such as Miles' Equation and the Shock Response Spectra, but it is unique in that it produces a realistic time history of the response. The most obvious error in the process, which is the effect of closely-spaced modes, was also assessed using the parallel application of several SDOF models, and the error is shown to be small. The application of this unique and tractable reduced-order methodology has enabled the SLS program to avoid substantial cost and schedule penalties if a redesign or change of material were required. It has also enabled quick analysis of a number of other structures undergoing the same or similar excitation fields, and quick assessment when the excitation and structural configuration has been altered due to design changes in the system.

Brown, Andrew M.↗
NASA NTRS2019

On-Orbit Xenon Refueling Loading Times and Transient Analysis

The Power and Propulsion Element (PPE) of the Lunar Orbital Platform-Gateway will demonstrate the first on-orbit refueling of xenon propellant for a solar electric propulsion system. An analysis was performed in Microsoft Excel to determine what factors influence the overall refueling time of a single 2,000-kilogram capacity xenon propellant tank, as well as provide estimates for overall refueling duration. Due to the high heat of compression of xenon, the propellant tank could exceed its maximum allowable temperature during refueling if the xenon flow rate and temperature are unregulated. In order to prevent overheating, a logic based "bang-bang" operation was used for refueling, shutting off the mass feed when the tank reached a maximum temperature. Heat is removed from the tank via radiation to the surrounding spacecraft bus. The analysis shows that optimizing key parameters such as mass flow rate into the tank, residual propellant in the tank during the onset of refueling, and tank diameter significantly reduces the overall refueling duration. Optimization is not straightforward, however, as the loading time does not trend monotonically with the parameters. Overall, the most significant impact on loading duration comes from altering the residual propellant in the tank. Increasing the mass of residual propellant from 2 percent to 20 percent reduces the overall refueling duration by 56 percent. Future work based on this analysis includes creation of a SINDA/FLUINT model and building a ground-based xenon refueling system emulator.

Xenon↗
NASA NTRS1997

Thermal Radiation Effects Analyzed in Translucent Composite and Thermal Barrier Coating

Ceramic parts and coatings are needed to withstand high temperatures in advanced aircraft engines. In hot environments, such as in the combustion chambers of these engines, infrared and visible radiation can penetrate into some ceramics and heat them internally. The internal temperatures depend on radiative effects combined with heat conduction, and on convection and radiation at the material boundaries. Since engine temperatures are high, radiant emission can be large from within translucent parts and coatings, and this must be included in the analysis. Transient and steady-state behavior are both important. During a transient, radiant penetration provides more rapid internal heating than conduction alone, and the temperature distributions are usually considerably different than for steady-state conditions; this can produce transient thermal stresses. Analytical and numerical methods are being used at the NASA Lewis Research Center to predict transient temperatures and heat flows in translucent materials. A transient analysis was done for a composite of two translucent layers. The layer refractive indices were larger than 1, producing internal reflections at the boundaries and at the internal interface. In addition, steady-state results were computed for a two-layer composite with one layer opaque. The results were used to assess the importance of internal radiation in a zirconia thermal barrier coating on a cooled metal wall. Since the radiative transfer equations are rather complex, especially when internal scattering is included, approximate methods are being investigated that might be convenient for computer design programs. An approximate two-flux method was used and verified by comparisons with solutions that used exact radiative transfer relations. The two-flux equations include scattering without increasing solution difficulty.

Siegel, Robert↗
NASA NTRS1989

Flight motor set 360L001 (STS-26R). (Reconstructed dynamic loads analysis)

A transient analysis was performed to correlate the predicted versus measured behavior of the Redesigned Solid Rocket Booster (RSRB) during Flight 360L001 (STS-26R) liftoff. Approximately 9 accelerometers, 152 strain gages, and 104 girth gages were bonded to the motors during this event. Prior to Flight 360L001, a finite element model of the RSRB was analyzed to predict the accelerations, strains, and displacements measured by this developmental flight instrumentation (DFI) within an order of magnitude. Subsequently, an analysis has been performed which uses actual Flight 360L001 liftoff loading conditions, and makes more precise predictions for the RSRB structural behavior. Essential information describing the analytical model, analytical techniques used, correlation of the predicted versus measured RSRB behavior, and conclusions, are presented. A detailed model of the RSRB was developed and correlated for use in analyzing the motor behavior during liftoff loading conditions. This finite element model, referred to as the RSRB global model, uses super-element techniques to model all components of the RSRB. The objective of the RSRB global model is to accurately predict deflections and gap openings in the field joints to an accuracy of approximately 0.001 inch. The model of the field joint component was correlated to Referee and Joint Environment Simulation (JES) tests. The accuracy of the assembled RSRB global model was validated by correlation to static-fire tests such DM-8, DM-9, QM-7, and QM-8. This validated RSRB global model was used to predict RSRB structural behavior and joint gap opening during Flight 360L001 liftoff. The results of a transient analysis of the RSRB global model with imposed liftoff loading conditions are presented. Rockwell used many gage measurements to reconstruct the load parameters which were imposed on the RSRB during the Flight 360L001 liftoff. Each load parameter, and its application, is described. Also presented are conclusions and recommendations based on the analysis of this load case and the resulting correlation between predicted and measured RSRB structural behavior.

Call, V. B.↗
NASA NTRS1991

Transient multidimensional analysis of nonconventional heat pipes with uniform and nonuniform heat distributions

A numerical analysis of transient heat pipe performance including nonconventional heat pipes with nonuniform heat distributions is presented. A body-fitted grid system was applied to a three-dimensional wall and wick model, which was coupled with a transient compressible quasi-one-dimensional vapor flow model. The numerical results were first compared with experimental data from cylindrical heat pipes with good agreement. Numerical calculations were then made for a leading edge heat pipe with localized high heat fluxes. Performance characteristics different from conventional heat pipes are illustrated and some operating limits concerning heat pipe design are discussed.

Cao, Y.↗
NASA NTRS1992

Transient loads analysis for space flight applications

A significant part of the flight readiness verification process involves transient analysis of the coupled Shuttle-payload system to determine the low frequency transient loads. This paper describes a methodology for transient loads analysis and its implementation for the Spacelab Life Sciences Mission. The analysis is carried out using two major software tools - NASTRAN and an external FORTRAN code called EZTRAN. This approach is adopted to overcome some of the limitations of NASTRAN's standard transient analysis capabilities. The method uses Data Recovery Matrices (DRM) to improve computational efficiency. The mode acceleration method is fully implemented in the DRM formulation to recover accurate displacements, stresses, and forces. The advantages of the method are demonstrated through a numerical example.

Thampi, S. K.↗
NASA NTRS1980

Recovered transient load analysis for payload structural systems

A recovered transient analysis technique is proposed wherein the results of a previous launch vehicle/payload system can be used to obtain the information on a new payload structure to be launched by an identical launch vehicle. The advantage of the proposed method is that the complete analysis can be performed within the payload organization with the same accuracy as that of a full scale, multiorganizational loads analysis. Also, the flight measured interface accelerations can be used as the forcing functions for more realistic representations of the dynamic environments.

Chen, J. C.↗
NASA NTRS1975

Shuttle LOX loading transient study. Task 2 milestone report. National space and technology laboratories (NSTL) LOX loading facility analysis

Transient thermodynamic analyses were made of the LOX loading system proposed for the space shuttle main propulsion test article (MPTA). This system is made up of a LOX replenish system and a main LOX line which include the barge tank, the lines, pumps, and valves between the barge and the orbiter (ORB) ground service equipment (GSE) interface, the MPTA fill system, the space shuttle main engine (SSME) chilldown bleed system, and the GSE vent system. System analyses include predictions of system performance sensitivity to operating sequence and LOX flowrate, temperature, and quality at the ORB/GSE interface. The transient thermodynamic conditions at the SSME feed line entrance, ET entrance (tank bottom), and the SSME bleed/GSE vent TEE are also included. The analyses are based on continuous SSME bleed flow during GSE facility chilldown.

Glasgow, V. L.↗
NASA NTRS1982

Transient thermal analysis of a titanium multiwall thermal protection system

The application of the SPAR thermal analyzer to the thermal analysis of a thermal protection system concept is discussed. The titanium multiwall thermal protection system concept consists of alternate flat and dimpled sheets which are joined together at the crests of the dimples and formed into 30 cm by 30 cm (12 in. by 12 in.) tiles. The tiles are mechanically attached to the structure. The complex tile geometry complicates thermal analysis. Three modes of heat transfer were considered: conduction through the gas inside the tile, conduction through the metal, and radiation between the various layers. The voids between the dimpled and flat sheets were designed to be small enough so that natural convection is insignificant (e.g., Grashof number 1000). A two step approach was used in the thermal analysis of the multiwall thermal protection system. First, an effective normal (through-the-thickness) thermal conductivity was obtained from a steady state analysis using a detailed SPAR finite element model of a small symmetric section of the multiwall tile. This effective conductivity was then used in simple one dimensional finite element models for preliminary analysis of several transient heat transfer problems.

Blosser, M. L.↗
NASA NTRS1977

Transient thermal analysis of fluid systems

Computer program performs transient thermal analysis of any 2-node to 200-node-thermal network, which transports heat by fluid flow convection. Program can be modified to add conduction along tubes and radiation.

Chandler, G. D.↗