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Results for “SHOCK MEASURING APPARATUS”

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 NTRS1967

Fluid physics

Three-dimensional viscous disturbances, shock structure of helium-argon mixtures, and magnetohydrodynamic experiments with large interaction parameter

MAGNETOHYDRODYNAMIC STABILITY↗
DOE OSTI2019

Effect of Prolonged Ultraviolet Radiation Exposure on the Blast Response of Fiber Reinforced Composite Plates

An experimental study with corresponding numerical simulations was conducted to evaluate the blast response of composite plates after prolonged exposure to ultraviolet radiation. Two composite materials were used in this study, namely carbon fiber/epoxy and glass fiber/vinyl ester. The composite materials consisted of four unidirectional fiber plies oriented in a [± 45°]s layup. The plates were placed in a QUV Accelerated Weathering Tester for 500 h of exposure on each face, totaling 1000 h of ultraviolet radiation exposure, equivalent to 2.5 MJ/m{sup 2} of energy. The QUV Accelerated Weathering Tester was equipped with eight UVA-340 lamps to provide real service life exposure conditions. Material characterization experiments were performed on virgin specimens, as well as specimens exposed to ultraviolet radiation for 1000 h to determine its effect on the mechanical properties of the composites. Blast experiments were conducted on the composite plates to investigate the dynamic response before and after exposure to ultraviolet radiation. The plates were clamped on all edges and subjected to an air blast using a shock tube apparatus. Three-dimensional digital image correlation was coupled with high-speed photography to obtain full-field displacements of the specimens during blast loading. Furthermore, three piezoelectric pressure transducers were mounted on the shock tube apparatus and utilized to measure the pressure history of the shock wave loading. The quasi-static material characterization showed that the tensile modulus E{sub 1} had minimal change after exposure to ultraviolet radiation for 1000 h. However, matrix-dominated properties such as the in-plane shear modulus G{sub 12} increased after exposure to ultraviolet light for both the carbon and glass fiber composites, which resulted in lower out-of-plane displacements during blast loading. For the carbon fiber plates, the forced vibration frequency induced by the transverse blast load was higher in plates exposed to ultraviolet radiation when compared to virgin specimens. However, for the glass fiber plates exposed to ultraviolet radiation, the forced vibration frequency decreased when compared to virgin specimens. Finally, the finite element simulations were in good agreement with the experimental results. The simulations revealed that the glass fiber plates exposed to ultraviolet radiation had higher failure strains at the boundary than virgin specimens, despite having higher stiffness. A parametric study in which higher loading was simulated also showed that the glass fiber plates experienced more damage after 1000 h of ultraviolet radiation exposure.

36 MATERIALS SCIENCE↗
NASA NTRS1973

Measurement of vibration rate of manually operated percussion machines

A special apparatus for measurement of accelerations of between 1 and 5000 g and shock stress pulses from 20 kg/cu cm up, with durations of 50.1 million sec and higher was designed and built. The amplitudes and shapes of the peak vibroshock pulses, arising during operation of a hammer, are obtained; the recording time of the continuous process is determined by the time of one revolution of the drum of a specially made mechanical photo attachment.

Aleksandrov, Y. V.↗
NASA NTRSDate not supplied

Development and Assessment of a New Particle Image Velocimetry System in the NASA GRC 225 cm2 Wind Tunnel

As part of an ongoing campaign to provide detailed and thorough measurements in a two-dimensional impinging shock-wave/boundary-layer interaction (SWBLI), a custom implementation of the Particle Image Velocimetry (PIV) measurement technique in the NASA Glenn 225 cm2 Wind Tunnel was constructed. The flow seeding apparatus was devised to locally seed the region of interest in the overall flowfield to avoid coating the viewing window with seed material. The ability of the PIV system to provide small particles which faithfully track the underlying gas-phase flowfield was of key importance for the success of this system to make quality measurements in the SWBLI flowfield. In order to optimize and assess the performance of the particle seeding system, PIV measurements were made across a planar oblique shock wave and particle response was analyzed to quantify the particle lag effects due to the finite inertia of the seed droplets. Video recordings from a camera placed in the wind tunnel plenum tank were also used to discern the near-field behavior of the seeded plume and guide the design evolution of the seeding apparatus. The resulting optimized seeding configuration was applied to make PIV measurements in the wind tunnel test section boundary layer to assess the seed particle spatial coverage and concentration. This sample boundary layer dataset provides an analog to the eventual boundary layer measurements to be made in the axisymmetric test section under much more challenged viewing conditions.

PIV↗
NASA NTRSDate not supplied

Development and Assessment of a New Particle Image Velocimetry System in the NASA GRC 225 cm2 Wind Tunnel

As part of an ongoing campaign to provide detailed and thorough measurements in a two-dimensional impinging shock-wave/boundary-layer interaction (SWBLI), a custom implementation of the Particle Image Velocimetry (PIV) measurement technique in the NASA Glenn 225 cm2 Wind Tunnel was constructed. The flow seeding apparatus was devised to locally seed the region of interest in the overall flowfield to avoid coating the viewing window with seed material. The ability of the PIV system to provide small particles which faithfully track the underlying gas-phase flowfield was of key importance for the success of this system to make quality measurements in the SWBLI flowfield. In order to optimize and assess the performance of the particle seeding system, PIV measurements were made across a planar oblique shock wave and particle response was analyzed to quantify the particle lag effects due to the finite inertia of the seed droplets. Video recordings from a camera placed in the wind tunnel plenum tank were also used to discern the near-field behavior of the seeded plume and guide the design evolution of the seeding apparatus. The resulting optimized seeding configuration was applied to make PIV measurements in the wind tunnel test section boundary layer to assess the seed particle spatial coverage and concentration. This sample boundary layer dataset provides an analog to the eventual boundary layer measurements to be made in the axisymmetric test section under much more challenged viewing conditions.

PIV↗
NASA NTRS1974

Stagnation pressure probe

A method and apparatus for measuring the stagnation pressure of supersonic velocity gas streams without the generation of shock waves which interfere with such measurements are given. The technique is insensitive to the type of gas and Mach number and is therefore particularly useful in the study of jet engine exhausts.

Goodyer, M. J.↗
NASA NTRS1990

Investigation of mechanical and thermal properties of microwave-sintered lunar simulant materials using 2.45 GHz radiation

The mechanical and thermal properties of lunar simulant material were investigated. An alternative method of examining thermal shock in microwave-sintered lunar samples was researched. A computer code was developed that models how the fracture toughness of a thermally shocked lunar simulant sample is related to the sample hardness as measured by a micro-hardness indentor apparatus. This technique enables much data to be gathered from a few samples. Several samples were sintered at different temperatures and for different times at the temperatures. The melting and recrystallization characteristics of a well-studied binary system were also investigated to see if the thermodynamic barrier for the nucleation of a crystalline phase may be affected by the presence of a microwave field. The system chosen was the albite (sodium alumino silicate) anorthite system (calcium alumino silicate). The results of these investigations are presented.

Meek, T. T.↗
NASA NTRS1971

Compression of helium to high pressures and temperatures using a ballistic piston apparatus

Some preliminary experiments are described which were carried out in a high enthalpy laboratory to investigate the compression of helium, a typical shock-tube driver gas, to very high pressures and temperatures by means of a ballistic piston. The purpose of these measurements was to identify any problem areas in the compression process, to determine the importance of real gas effects duDC 47355s process, and to establish the feasibility of using a ballistic piston apparatus to achieve temperatures in helium in excess of 10,000 K.

Roman, B. P.↗