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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Electronically controlled mechanical seal for aerospace applications--Part 2: Transient tests

An electronically controlled mechanical seal for use as the purge gas seal in a liquid oxygen turbopump has been fabricated and tested under transient operating conditions. The thickness of the lubricating film is controlled by adjusting the coning of the carbon face. This is accomplished by applying a voltage to a piezoelectric actuator to which the carbon face is bonded. The seal has been operated with a closed-loop control system that utilizes either the leakage rate or seal face temperature as the feedback. Both speed and pressure transients have been imposed on the seal. The transient tests have demonstrated that the seal is capable of maintaing low leakage rates while limiting face temperatures.

Wolff, Paul J.↗
NASA NTRS1976

Computerized thermal transient test console

A system for nondestructively testing electroexplosive devices by the thermal transient test technique is described. The signal, which is generated by pulsing the electroexplosive device bridgewire is reduced to digital form. The data is then interpreted by an appropriate program and the essential electrothermal parameters are resolved. The system is fast, eliminates arbitrary interpretation of the analog, and lends itself to production testing.

Menichelli, V. J.↗
NASA NTRS1990

Analysis of the single-blow transient testing technique for perforated plate heat exchangers

An analysis of the single-blow transient testing technique for heat exchanger surfaces is made for perforated plate and similar discontinuous surfaces. The model assumes that there is no temperature variation across each plate, and allows for axial conduction in spacers: the resulting axial fluid temperature profile is discontinuous, rather than the usual continuous profile. Numerical solutions are obtained to the resulting set of coupled first-order differential equations for a step change in inlet fluid temperature. Results are presented in tabular form, which allow the heat transfer coefficients to be calculated from test data using the maximum slope technique.

Rodriguez, Jose I.↗
NASA NTRS1989

Igniter heater EMI transient test

Testing to evaluate Redesigned Solid Rocket Motor igniter heater electromagnetic interference (EMI) effects on the Safe and Arm (S and A) device was completed. It was suspected that EMI generated by the igniter heater and it's associated electromechanical relay could cause a premature firing of the NASA Standard Initiators (NSIs) inside the S and A. The maximum voltage induced into the NSI fire lines was 1/4 of the NASA specified no-fire limit of one volt (SKB 26100066). As a result, the igniter heaters are not expected to have any adverse EMI effects on the NSIs. The results did show, however, that power switching causes occasional high transients within the igniter heater power cable. These transients could affect the sensitive equipment inside the forward skirt. It is therefore recommended that the electromechanical igniter heater relays be replaced with zero crossing solid state relays. If the solid state relays are installed, it is also recommended that they be tested for EMI transient effects.

Cook, M.↗
NASA NTRS1990

Thermal-Transient Testing Of Turbine Blades

Testing apparatus applies pulses of heat to turbine blade to determine resistance to thermal fatigue. Uses nonintrusive inductive heating and records distribution of temperature on blade with infrared video camera. Allows precise control of heating and cooling. Designed for testing blades used in advanced high-pressure, high-temperature turbines.

Wagner, William R.↗
NASA NTRS1988

Space Shuttle solid rocket motor testing for return to flight - Transient Pressure Test Article test program

The Transient Pressure Test Article (TPTA) test program, which is being conducted at a new facility at NASA-Marshall, is described. The facility is designed to test and verify the sealing capability of the redesigned solid rocket motor's (RSRM) field, igniter, and nozzle joints. The test article consists of full-scale RSRM hardware loaded with inert propellant and assembled in a short stack configuration. The test facility is described as well as test implementation, test effectiveness, and test results.

Vibbart, Charles M.↗
NASA NTRS1989

Transient Pressure Test Article Test Program

The Transient Pressure Test Article (TPTA) test program is being conducted at a new test facility located in the East Test Area at the National Aeronautics and Space Administration's (NASA's) Marshall Space Flight Center (MSFC) in Huntsville, Alabama. This facility, along with the special test equipment (STE) required for facility support, was constructed specifically to test and verify the sealing capability of the Redesigned Solid Rocket Motor (RSRM) field, igniter, and nozzle joints. The test article consists of full scale RSRM hardware loaded with inert propellant and assembled in a short stack configuration. The TPTA is pressurized by igniting a propellant cartridge capable of inducing a pressure rise rate which stimulates the ignition transient that occurs during launch. Dynamic loads are applied during the pressure cycle to simulate external tank attach (ETA) strut loads present on the ETA ring. Sealing ability of the redesigned joints is evaluated under joint movement conditions produced by these combined loads since joint sealing ability depends on seal resilience velocity being greater than gap opening velocity. Also, maximum flight dynamic loads are applied to the test article which is either pressurized to 600 psia using gaseous nitrogen (GN2) or applied to the test article as the pressure decays inside the test article on the down cycle after the ignition transient cycle. This new test facility is examined with respect to its capabilities. In addition, both the topic of test effectiveness versus space vehicle flight performance and new aerospace test techniques, as well as a comparison between the old SRM design and the RSRM are presented.

Vibbart, Charles M.↗
NASA NTRS1988

Transient Pressure Test Article test program

The Transient Pressure Test Article test program being conducted at NASA-Marshall is described. The main goal of the TPTA test program is to provide data to verify the sealing capability of the redesigned SRM field joints, the nozzle-to-case joint, and the igniter joint. The TPTA test program can be used to demonstrate the assembly/disassembly and reusability of the redesigned joints along with the adequacy of assembly/disassembly tooling, procedures, and inspections.

Vibbart, Charles M.↗
NASA NTRS1984

Transient vibration test criteria for spacecraft hardware

Transient vibration test criteria, developed for spacecraft hardware, provide a test rationale to verify the capability of the hardware to withstand the low and mid frequency transient vibration environments induced by launch vehicle events. A test method, consisting of a series of discrete frequency, limited cycle, modulated sine wave pulses, was developed to avoid the slow swept sine drawbacks, yet provide a repeatable test that would excite all frequencies. The shape of the waveform is that of the classic response of the mass of a one degree of freedom system when it is base-excited by an exponentially decayed sine wave transient. Criteria were developed to define pulse amplitudes, shapes, and center frequencies from spacecraft loads analyses. Test tolerance criteria were also developed and specified. The transient vibration test criteria were implemented on spacecraft flight hardware and provided a more realistic test simulation (i.e., less conservative) for qualification of spacecraft hardware without risk of undertest.

Kern, D. L.↗
NASA NTRS1991

The new Section 23 of DO160C/ED14C lightning testing of externally mounted electrical equipment

The new Section 23 is introduced which has only very recently been fully approved by the RTCA for incorporation into the first revision of DO160C/ED14C. Full threat lightning direct effects testing of equipment is entirely new to DO160, the only existing lightning testing is transient testing for LRU's (Line Replaceable Units) by pin or cable bundle injection methods, for equipment entirely contained within the airframe and assumed to be unaffected by direct effects. This testing required transients of very low amplitude compared with lightning itself, whereas the tests now to be described involve full threat lightning testing, that is using the previously established severe parameters of lightning appropriate to the Zone, such as 200 kA for Zone 1A as in AC20-136. Direct effects (i.e., damage) testing involves normally the lightning current arc attaching to the object under test (or very near to it) so submitting it to full potential for the electric, mechanical, thermal and shock damage which is caused by high current arcing. Since equipment for any part of the airframe require qualification, tests to demonstrate safety of equipment in fuel vapor regions of the airframe are also included.

Burrows, B. J. C.↗
NASA NTRS1988

Transient Pressure Test Article (TPTA) 1.1 and 1.1A, volume 1

This final test report presents the results obtained during the static hot firing and cold-gas high Q tests of the first Transient Pressure Test Article (TPTA) 1.1. The TPTA consisted of field test joints A and B, which were the original RSRM J-insulation configuration, with a metal capture feature. It also consisted of a flight configuration nozzle-to-case test joint (Joint D) with shorter vent slots. Fluorocarbon O-rings were used in all the test joints. The purpose of the TPTA tests is to evaluate and characterize the RSMR field and nozzle-to-case joints under the influence of ignition and strut loads during liftoff anf high Q. All objectives of the cold-gas high Q (TPTA 1.1A) test were met and all measurements were close to predicted values. During the static hot-firing test (TPTA 1.1), the motor was inadvertently plugged by the quench injector plug, making it a more severe test, although no strut loads were applied. The motor was depressurized after approximately 11 min using an auxiliary system, and no anomalies were noted. In the static hot-firing test, pressure was incident on the insulation and the test joint gaps were within the predicted range. During the static hot-firing test, no strut loads were applied because the loading system malfunctioned. For this test, all measurements were within range of similar tests performed without strut loads.

Rebells, Clarence A.↗
NASA NTRS1997

A Technique for Transient Thermal Testing of Thick Structures

A new open-loop heat flux control technique has been developed to conduct transient thermal testing of thick, thermally-conductive aerospace structures. This technique uses calibration of the radiant heater system power level as a function of heat flux, predicted aerodynamic heat flux, and the properties of an instrumented test article. An iterative process was used to generate open-loop heater power profiles prior to each transient thermal test. Differences between the measured and predicted surface temperatures were used to refine the heater power level command profiles through the iteration process. This iteration process has reduced the effects of environmental and test system design factors, which are normally compensated for by closed-loop temperature control, to acceptable levels. The final revised heater power profiles resulted in measured temperature time histories which deviated less than 25 F from the predicted surface temperatures.

Horn, Thomas J.↗
NASA NTRS1991

Diffuse dispersive delay and the time convolution/attenuation of transients

Test data and analytic evaluations are presented to show that relatively poor 100 KHz shielding of 12 Db can effectively provide an electromagnetic pulse transient reduction of 100 Db. More importantly, several techniques are shown for lightning surge attenuation as an alternative to crowbar, spark gap, or power zener type clipping which simply reflects the surge. A time delay test method is shown which allows CW testing, along with a convolution program to define transient shielding effectivity where the Fourier phase characteristics of the transient are known or can be broadly estimated.

Bittner, Burt J.↗
NASA NTRS1993

Actively controlled shaft seals for aerospace applications

An electronically controlled mechanical seal for use as the purge gas seal in a liquid oxygen turbo pump has been fabricated and tested under transient operating conditions. The thickness of the lubricating film is controlled by adjusting the coning of the carbon face. This is accomplished by applying a voltage to a piezoelectric actuator to which the carbon face is bonded. The seal has been operated with a closed-loop control system that utilizes either the leakage rate or the seal face temperature as the feedback. Both speed and pressure transients have been imposed on the seal. The transient tests have demonstrated that the seal is capable of maintaining low leakage rates while limiting the face temperatures.

Salant, Richard F.↗
NASA NTRS1992

Multi-axis transient vibration testing of space objects: Test philosophy, test facility, and control strategy

IABG has been using various servohydraulic test facilities for many years for the reproduction of service loads and environmental loads on all kinds of test objects. For more than 15 years, a multi-axis vibration test facility has been under service, originally designed for earthquake simulation but being upgraded to the demands of space testing. First tests with the DFS/STM showed good reproduction accuracy and demonstrated the feasibility of transient vibration testing of space objects on a multi-axis hydraulic shaker. An approach to structural qualification is possible by using this test philosophy. It will be outlined and its obvious advantages over the state-of-the-art single-axis test will be demonstrated by example results. The new test technique has some special requirements to the test facility exceeding those of earthquake testing. Most important is the high reproduction accuracy demanded for a sophisticated control system. The state-of-the-art approach of analog closed-loop control circuits for each actuator combined with a static decoupling network and an off-line iterative waveform control is not able to meet all the demands. Therefore, the future over-all control system is implemented as hierarchical full digital closed-loop system on a highly parallel transputer network. The innermost layer is the digital actuator controller, the second one is the MDOF-control of the table movement. The outermost layer would be the off-line iterative waveform control, which is dedicated only to deal with the interaction of test table and test object or non-linear effects. The outline of the system will be presented.

Lachenmayr, Georg↗