Chamber pressure

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

Pressure-regulating composite cartridge with gas expansion zone

Abstract: A plastic-cased metal-headed ammunition casing for high-powered rifle and cannon cartridges is described in which the plastic case (12) has a pressure regulating baffle (44) or wall in the forward end thereof to regulate and control the development of chamber pressure and directs pressure into a space around the bore of the projectile (10) prior to movement of the projectile The cartridge is charged with a given charge of powder (38) and the cap or head (14) securely fastened to the rearward portion of the plastic casing An expandable sleeve (124) may be used to stabilize the head-casing interfit The head provides sufficient resistance to the residual pressure after firing so that the cartridge can be used in rapid fire automatic weapons

Jet recirculation method for vacuum carburizing

Abstract: A method and apparatus for recirculation of atmosphere in a vacuum furnace which comprises a recirculation loop in which there is a low pressure line from the furnace chamber leading to a recirculation pump which pumps the recycled gas at a higher pressure to a high pressure line back into the furnace chamber. A means to analyze the furnace atmosphere is in communication with the high pressure line and signals its measurements of the atmosphere analysis to a valve on an enriching line. The enriching line passes enriched gas into either the high pressure line or the furnace chamber as the valve opens or closes. A means is provided to withdraw the gas from the furnace chamber in order to maintain the desired furnace chamber pressure as enriching gas is added.

Experimental Study of a Nanoparticle Virtual Impactor

Abstract: A nanoparticle virtual impactor was constructed and its performance under different operating conditions was investigated. Experimental evaluations showed that the nanoparticle virtual impactor has a 50% cutoff size ranging from 15 to 60nm. Further, the cutoff size of 60nm can be achieved at an impactor chamber pressure of 220torr when the nozzle upstream pressure is 760torr. This pressure level is much higher than that of thin-plate orifice nozzle impactors, which require 12torr to achieve the cutoff size of 66nm. Thus, the proposed virtual impactor can be operated with a small vacuum pump, which is more preferable for practical applications.

Gassing arc chamber wall material effect on post current-zero recovery voltage breakdown

Abstract: Experimental measurements and theoretical calculations were used to identify and quantify important factors that arc chamber insulation has on post-current zero recovery voltage. Gas analysis, pressure measurements, and post current-zero breakdown voltages were used to rank arc chamber wall material according to breakdown voltage. Generally, breakdown voltage increased with pressure at breakdown. However, nylon 6/6, which had a reduced pressure rise but still had a relatively high breakdown strength, was an exception. Pyrolysis of each material was performed to identify gases produced by arc chamber materials. Gas chromatography was used to determine the types and amounts of gases emitted by the various wall materials. Unlike most other materials, nylon 6/6 sample showed a relatively low percentage of hydrogen but high ethylene percentage, along with no carbon residue. The combination of gases that produced high pressures and low solid carbon had the higher breakdown strength. Theoretical calculations showed breakdown strength to depend on the pressure at breakdown, cathode temperature, and contact material (Ag/W), and carbon (C) deposits on the contacts. Based on theoretical calculations, it was postulated that the wall materials not only determined the pressure at breakdown but also, the amount of carbon deposited on the cathode surface (C, along with the W and oxides, provided a good source for thermionic emission). The greater the amount of carbon deposited on the cathode surface, produced from the insulation, the lower the breakdown strength for a given amount of W. This could explain why nylon performed well, since it produced no carbon residue during pyrolysis. Theoretical calculations of the breakdown voltage, based on dielectric breakdown of the plasma sheath formed in front of the cathode, were also compared to experimental values to obtain estimates of sheath thickness and cathode temperatures. Sheath breakdown values were obtained numerically by solving Townsend's criteria for various sheath thickness and cathode temperatures. Experimental values were plotted on the theoretical curves to obtain estimates of the plasma parameters. In addition to ranking the insulation, peak chamber pressure and arc voltages are given for practical molded case circuit breaker (MCCB) design.

Numerical and Experimental Investigation on Vortex Injection in Hybrid Rocket Motors

Abstract: A study on vortex injection in hybrid rocket motors with nitrous oxide as the oxidizer and paraffin as the fuel has been performed. The investigation followed two paths: first of all, the flow field was simulated with a CFD code, and then burn tests were performed on a lab-scale rocket. The CFD analysis had the dual purpose to help the design of the lab motor and to understand the physics underlying the vortex flow coupled with the combustion process. Numerical analysis was focused on the comparison with axial injection. Vortex injection produces a more diffuse flame in the combustion chamber and improves the mixing process of the reactants, both aspects concurring to increase the efficiency of the motor. A helical streamline develops downstream the injection region, and the pitch is highly influenced by combustion, that tends to straighten the flow due to the acceleration imposed by the temperature rise to the axial velocity component. The tangential velocity, on the contrary, is far less influenced by this effect. Experimental tests with the same chamber geometry have been performed with both pressurized and self-pressurized oxidizer. Measured performances showed an increase in regression rate up to 51% and a combustion efficiency that rises from values lower than 80% in the axial injection configuration up to more than 90% with vortex. Moreover, a reduction of the instabilities in the chamber pressure has been measured. Issues requiring further investigation concern the motor exhausts: both experimental and numerical analyses showed that there is a residual tangential velocity component in the plume; this, coupled with a noise suppressor system downstream the nozzle in the test apparatus, showed severe instabilities in the vortex configuration thrust measurements, not reported in chamber pressure burn data and not affecting axial injection.