Chamber pressure

About: Chamber pressure is a research topic. Over the lifetime, 2988 publications have been published within this topic receiving 30725 citations.

Effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties of amorphous carbon films prepared by pulsed laser deposition

Abstract: We have investigated the effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties of amorphous carbon thin films prepared by pulsed laser deposition. The amorphous carbon films were deposited in various atmospheres such as nitrogen and argon at different chamber pressures. We used Raman spectroscopy to study the bonding characteristics of the deposited amorphous carbon films. Atomic force microscopy and optical microscopy were utilized to observe the surface conditions and the microstructures of the deposited films. Nanoindentation measurements were carried out on various samples prepared under different conditions to study the effect of chamber pressure and atmosphere on the elastic modulus and nanohardness of the films. It was found that reduced vacuum leads to formation of amorphous carbon films with reduced elastic modulus and nanohardness. Amorphous carbon films prepared under higher chamber pressures exhibit an increased density of particulates and significantly ...

Thermal Decomposition of Hydrogen Peroxide, Part I: Experimental Results

Abstract: Thermal decomposition is an important process in propulsion systems that use hydrogen peroxide (HP). Neither a combined vaporization-decomposition model nor a fundamental understanding of the way liquid HP vaporizes and decomposes in these rocket applications exist. Results are presented from an experimental study of the combined thermal decomposition of HP at rocket-type conditions. A liquid spray of HP is injected into a cross stream of HP decomposition products at chamber pressures ranging from 2.0 to over 5.5 MPa. Two injectors with different orifice diameters are used. Experimental parameters include flow rates of the decomposition products and liquid injectant, HP concentration, chamber geometry, and momentum ratio between the liquid injectant and the decomposition stream. A decomposition efficiency of the liquid HP is determined based on the ratio between measured chamber pressure and chamber pressure calculated by equilibrium chemistry. An analysis of the crossflow injection is used to assess the effects of spray trajectory. Decomposition efficiencies ranging between 10 and 90% were measured. The results show that decomposition efficiency is inversely proportional to the fractional amount of liquid injectant flow rate, linearly proportional to residence time, and that higher concentration HP decomposes at a faster rate.

Pneumatic die cushion equipment

Abstract: A closed type cylinder unit, instead of the open-to-atmosphere type cylinder unit of conventional equipment forms part of the die cushion apparatus. Based on the principle that the die cushion capability by the closed type cylinder unit is determined by the differential pressure between the lower chamber pressure and the upper chamber pressure, the differential pressure is controlled in such manner that the lower chamber and the upper chamber communicate with each other through a check valve, which is opened when the differential pressure exceeds a preset differential pressure value. As the upper and lower chambers communicate through a shut-off valve, which hinders the excessive increase of the upper chamber pressure when the piston goes up. Further, the form of the check valve is changed for conveniently changing and adjusting the die cushion apparatus during press fabrication.

Effects of liquid-oxygen post biasing on SSME injector wall compatibility

Abstract: An experimental investigation has been carried out to examine the effects of liquid-oxygen (LOX) post biasing of a shear coaxial injector on the behavior of the spray near a chamber wall. The experimental work was performed with inert propellant simulants in a high-pressure chamber. Injector flow rates and chamber pressure were designed to match the space-shuttle-main-engine (SSME) injector gas-to-liquid density and velocity ratio at the point of propellant injection. Measurements of liquid mass-flux, gas-phase velocity, and droplet size were made using mechanical patternation and phase Doppler interferometry techniques. The measurements revealed that the liquid mass-flux distribution shifts away from the wall with increasing LOX postbias away from the wall. The shift in the liquid flux distribution was much greater than that caused by the angling of the LOX post alone. Gas velocity near the wall simultaneously increased with increasing LOX post bias away from the wall. The increase in wall-side gas velocity was caused by the higher fraction of gas injected on the wall side of the injector as a result of the eccentricity at the injector exit. The net result was a decrease in mixture ratio near the wall. Estimates of heat transfer and engine performance relative to the unbiased case are presented.