Showing papers on "Chamber pressure published in 1990"

Fundamentals of ion‐beam‐assisted deposition. I. Model of process and reproducibility of film composition

Abstract: An ion‐beam‐assisted‐deposition (IBAD) system is under development to fabricate Si1−x Nx films for optical devices. Reproducible film composition requires characterization of the relationship between the incorporated nitrogen atom fraction x and the real time experimental measurable quantities. In this paper a simple model is presented which relates the film composition x to the measured beam current density JF , the vapor impingement rate Q, and the chamber pressure p. Effects included in the model are reflection of energetic particles, sputtering from the film surface, and charge exchange neutralization of the ions. Each term in the model is examined as a potential source of both systematic and random deviations of the data from the model. Data on film composition as a function of the nitrogen ion current to deposition rate ratio are presented for several sets of ion source voltages and chamber pressures. It is shown that by modifying the deposition system so as to minimize the identified sources of err...

Droplet Sizes and Velocities in a Transient Diesel Fuel Spray

Abstract: : Simultaneous droplet sizes and velocities were obtained for a transient diesel fuel spray in a quiescent chamber at atmospheric temperature and pressure. Instantaneous injection pressure, needle lift, and rate of injection were also measured, allowing calculation of the instantaneous nozzle discharge coefficient. Short-exposure still photographs were obtained at various chamber pressure and densities to further investigate this spray. Correlations between droplet size and velocity were determined at each crank angle to observe the detailed nature of the transient events occurring in this transient diesel fuel spray. As expected, peak mean and rms velocities are observed in the center of the spray. Measured average velocities are consistent with a calculated value, using the discharge coefficient for the nozzle and the known rate of fuel injection. The spray was nearly symmetric, with higher velocities occurring near the injector tip, and the radial dependence of velocity consistent with that observed from the spray photographs. Factors observed to effect the droplet size and velocity distributions and history include pump speed, fuel quantity delivered, and needle lift. Reprints. (aw)

Comparison of combustion experiments and theory in polyethylene solid fuel ramjets

Abstract: A research program was carried out to validate numerical simulation of the flow and combustion processes in the combustion chamber of a solid fuel ramjet with experimental results Experimental data were obtained by burning cylindrical fuel grains made of polyethylene in a solid fuel ramjet using a connected pipe facility For numerical simulation a computer code describing two-dimensional, steady-state turbulent flows through channels with and without a sudden expansion was developed Three different combustion models are incorporated, one based on finite-rate chemical kinetics, the other two based on the diffusion flame concept For the validation, emphasis was laid on comparing regression rate data in relation to chamber pressure, air mass flow, inlet air temperature, and step height Attention was also paid to reattachment length, temperature, and C2 and CH concentrations In some cases, a comparison with findings from other investigators was also made The results show good agreement between predicted and observed behavior downstream of the recirculation zone In the recirculation zone, however, the agreement is rather poor and can be attributed to the inability of the k-e model to predict heat transfer behind a rearward facing step accurately It is shown that the effective heat of gasification of the fuel is an important parameter A better understanding of its behavior in relation to combustion chamber conditions is needed Computed regression rate data are relatively insensitive to the combustion model employed

A large-area transition radiation detector

Abstract: The construction and the operation of a large-area transition radiation detector (TRD) for the NA31 experiment at CERN are described. The TRD incorporates several novel features for stabilizing the detector response. The density of the gas mixture (xenon+helium+methane) in the detection chambers is matched to the carbon dioxide gas in the surrounding radiators by tuning the helium concentration to avoid a hydrostatic pressure difference, which would deform the chamber walls. The chamber pressure is continuously regulated by computer control to maintain it to within 1 μbar of the radiator pressure. The gas gain of each of the four chambers is regulated to better than 0.2% by changing the high voltage under computer control, using the pulse-height spectra of 16 109 Ca sources mounted on the chambers. The results of performance studies are described. The detector has a pion efficiency of 98.7% with an electron rejection of a factor of 10.

Variable capacity wobble plate compressor

Abstract: A variable capacity wobble plate compressor includes a wobble plate (36) in the crank chamber (7) for adjusting the piston stroke; a control valve (45) for controlling the chamber pressure in the crank chamber to adjust the angle of the wobble plate; a pressure sensor (53); a rotary speed sensor (56); a heat load sensor (61); and/or a vibration sensor (62); and a control unit responsive to a signal from at least one of the sensors for controlling the control valve to prevent the compressor from entering an unstable zone.

Computation of viscous chemically reacting flows in hybrid rocket motors using an upwind LU-SSOR scheme

Abstract: A time-dependent, two-dimensional, axisymmetric numerical solution technique has been developed to model viscous chemically reactive flow in hybrid solidiiquid rocket motors. The solution empfoys an implicit finite-volume, lower-upper symmetric successive overrelaxation scheme (LU-SSOR) based on fluxdifference splitting of a Roe-type approximate Riemann solver. The combustion process is modeled by a twospecies one-step finite-rate reaction model whereas turbulence is simulated by the Baldwin-Lomax algebraic eddy viscosity turbulence model. The solution provides predictions of flow structure and combustion within. the solid grain pod and throughout the nozzle for any oxidizer flow rate. In addition, motor operating chamber pressure and grain regression rate are also computed. Numerical simulation of a labscale motor firing is presented, and comparison with the experimental data shows good agreement between predicted and measured chamber pressure and regression rate. ,

Particle removal from surfaces by pressure change

Abstract: This invention provides methods and apparatus for removing contaminant particles from a surface of an article (113). In one embodiment, a surface of an article (120) to be cleaned is immersed in cleaning liquid (117) in a pressure vessel chamber (115) and a dissolving gas (119) is dissolved into the cleaning liquid (117) at high pressure. A pressure relief valve (123) is then suddenly opened, bubbles spontaneously form in the liquid, and the contaminants are dislodged from the surface of the article (113) and carried toward the surface of the liquid (117) by the bubbles. A small amount of the cleaning liquid containing the dissolved gas can further be caused to form a thin frozen layer (120) on the surface of a submerged article to be cleaned, before the chamber pressure is then dropped suddenly, causing a spontaneous bubble formation in the frozen layer that moves the contaminant particles away from the surface to be cleaned. The contaminants and cleaning liquid or the frozen layer are then removed from the surface.

IC engine oil pressure regulator - has piston control chamber connected to oil circuit pump assembly

Abstract: The oil pressure regulator in a variable compression piston control chamber is formed between an inner piston joined to a connecting rod and an outer piston adjusting on the inner piston The chamber is connected by channel to an oil circuit pump and chamber pressure is controlled by a pressure regulating valve working as a function of operating parameters The oil pump and regulating valve (20) complete a variable pump used to regulate the oil pressure in the control chamber (42) USE/ADVANTAGE - Ic engines, engine oil Space-saving design offers precise sensitive pressure control for all running conditions, reacting ahead of knocking onset

Process and apparatus for the treatment of tobacco material

Abstract: Process and apparatus for the treatment of tobacco material and other biological materials includes a mechanism comprising a dynamic seal having components having cooperating movable surfaces for sealing a treatment chamber that substantially prevents the passage of fluid at the treatment chamber pressure during movement of the components for introducing material into and removing material from the chamber. The seal components preferably comprise advanced structural ceramic components having a hardness of at least 900 kg/mm 2 and a flatness of at least 70 microinches. The process is preferably conducted at supercritical gaseous conditions.

Pilot regulator for valves

Abstract: A pilot regulator has a main housing with a sensing chamber and a separate receiving chamber. The sensing chamber connects to the system for sensing. The receiving chamber is adapted to connect its inlet to the system upstream of the pilot and to the load line of the valve to be controlled and to connect its outlet downstream thereof, a cartridge containing a complete valve is removably received in the receiving chamber in position to control flow therethrough between the inlet and outlet. And a mechanism is disclosed for opening and closing the valve in response to sensing chamber pressure changes. The cartridge with its valve are removable as a unit for repair, mode change or replacement without disturbing connections to system.

Control apparatus used for a refrigerant circuit having a compressor with a variable displacement mechanism

Abstract: An automobile air conditioner system including a refrigerant circuit having a condenser, expansion element, evaporator and wobble plate type compressor with a variable displacement mechanism. Two passages communicate between the crank chamber and the suction chamber in the cylinder block. A bellows is disposed in a first passage and controls the communication between the crank chamber and the suction chamber response to crank chamber pressure. A control valve is disposed in the second passage and controls communication between the crank chamber and the suction chamber in the second passage in response to a signal representing the temperature of the air immediately leaving from the evaporator. An electric clutch is mounted on the compressor in order to intermittently transmit the rotational motion of an automobile engine to the drive shaft of the compressor in response to the signal. The automobile air conditioning system is provided with a demist switch for preventing the reduction of visibility through the windshield of the automobile. The operation of the control valve overrides the operation of the bellows without regard to the temperature signal when the demist switch is turned on.

Vaporizer for internal combustion steam engine

Abstract: An alcohol/water fuel vaporizer for use in an internal combustion steam engine. The vaporizer comprises an exhaust gas chamber through which engine exhaust is passed and a vapor chamber for the generation and retention of pressurized fuel vapor. The exhaust gas chamber includes a plurality of baffles to direct the flow of the gas against a crown sheet, the latter sheet being heated thereby. The crown sheet forms the dividing partition between the vapor and exhaust gas chambers. A fuel preheater is positioned in the vapor chamber through which engine coolant is passed. A plurality of switchable fuel injectors in the vapor chamber controllably admit and spray fuel onto the preheater and crown plate in response to engine power demands and vapor chamber pressure.

Process and apparatus for the treatment of material such as tobacco

Abstract: Process and apparatus for the treatment of tobacco material and other biological materials includes a mechanism comprising a dynamic seal having components (120,122) having cooperating movable surfaces for sealing a treatment chamber (50) that substantially prevents the passage of fluid at the treatment chamber pressure during movement of the components for introducing material into and removing material from the chamber. The seal components preferably comprise advanced structural ceramic components having a hardness of at least 900 kg/mm² and a flatness of at least 70 microinches (1.8 micrometres). The process is preferably conducted at supercritical gaseous conditions.

Optimization of the propulsion cycles for advanced shuttles. II - Performance model methodology

Abstract: In 1988 computer codes from NASA and DLR were combined to analyze and optimize rocket engines for advance launch vehicles. Further effort has addressed performance propulsion parameters such as chamber pressure, cycle selection (including mixed and tripropellant cycles), nozzle extension, and new technologies. Results of the study indicate that lower dry masses can be reached with the staged combustion cycle than with the gas-generator cycle, using oxygen/hydrogen at relatively high mixture ratio (7:1) and modest chamber pressure (220 bar). For low dry masses the staged combustion cycle is only excelled by the dual-expander cycle using hydrogen and propane as fuels. The emphasis here is to explain the procedure and boundary conditions used for the analysis and the variety of configurations treated, as well as to demonstrate the methods used by presenting some of the major results.

Cooling of rocket thrust chambers with liquid oxygen

Abstract: Rocket engines using high pressure liquid oxygen (LOX) and kerosene (RP-1) as the propellants have been considered for future launch vehicle propulsion. Generally, in regeneratively cooled engines, the fuel is used to cool the combustion chamber. However, hydrocarbons such as RP-1 are limited in their cooling capability at high temperatures and pressures. Therefore, LOX is being considered as an alternative coolant. However, there has been concern as to the effect on the integrity of the chamber liner if oxygen leaks into the combustion zone through fatigue cracks that may develop between the cooling passages and the hot-gas side wall. To address this concern, an investigation was previously conducted with simulated fatigue cracks upstream of the thrust chamber throat. When these chambers were tested, an unexpected melting in the throat region developed which was not in line with the simulated fatigue cracks. The current experimental program was conducted in order to determine the cause for the failure in the earlier thrust chambers and to further investigate the effects of cracks in the thrust chamber liner upstream of the throat. The thrust chambers were tested at oxygen-to-fuel mixture ratios from 1.5 to 2.86 at a nominal chamber pressure of 8.6 MPa. As a result of the test series, the reason for the failure occurring in the earlier work was determined to be injector anomalies. The LOX leaking through the simulated fatigue cracks did not affect the integrity of the chambers.

Shallow Underground Tunnel/Chamber Explosion Test Program Summary Report

Abstract: : The Shallow Underground Tunnel/Chamber Explosion Test Program was a large-scale test simulating an accidental explosion in a shallow underground magazine. The purpose of the test was to record the nature and extent of hazardous effects produced by the explosion. The program was divided into four study areas; tunnel/chamber pressure, external airblast, external ground motion, and ejecta/debris. The tunnel/chamber pressure measurements provided data on the internal explosion environment and the exit pressure at the access tunnel portal. The external airblast measurements established the airblast hazard ranges from the tunnel portal. Ground motion and artificial debris measurements furnished data on hazard ranges for ejecta produced by rupture of the chamber overburden, and for debris blown from the tunnel portal. An analysis of the data was presented comparing the results to current hazard range criteria specified in the DOD and NATO manuals for ammunition and explosives safety.

Monitoring spray action of spray gun - measuring pressure in chamber and comparing with predetermined pressure threshold value

Abstract: The spray gun has a chamber for the substance to be sprayed which is ejected under pressure and filled up in the pauses. A control signal for a pressure amplifier starts the spraying process. The chamber pressure is measured. When the spraying starts the pressure is compared with a predetermined pressure threshold value (7). A check is made to ascertain if the exceeding of the latter lies within a predetermined period. An indication is given if the threshold value is not attained or is exceeded during the set period. USE - Ensuring good, even spray work.

Automatic switching valve

Abstract: A valve including spools each responsive to fluid pressure and each spring biased to an open position. Multiple sources of pressure, such as tanks, serve the valve. Tank pressure is directed in sequence through a spool in the open position to an end chamber of the remaining spool to shift the latter spool for uninterrupted passage of fluid pressure into an outlet of the end chamber and past a flow separator spool to a pressure regulator. Switching to a second tank occurs automatically upon a drop in end chamber pressure permitting shifting of a spool to an open position to direct fluid pressure to the end chamber of the remaining spool.

Hydraulic valve lifter

Abstract: A hydraulic valve lifter is disclosed which does not require a source of pressurized lubricating fluid, and is particularly suitable for engines using a splash lubrication system. The engine crankcase oil is transferred from the cam surface through a check valve into the pressure chamber of the lifter. The check valve is operated by the pressure differential between the chamber pressure and the pressure at the cam surface. The check valve may also be operated by the cam itself.

Evaluation circuit for piezo-resistive pressure sensor - has resistive bridge contg. two piezo-resistive arms, operational amplifier all fitting on single hybrid

Abstract: The evaluation circuit for a piezoresistive pressure sensor contains a bridge circuit of four resistances (R1-R4) with one diagonal connected between the supply voltage and earth and with the other diagonal connected to an operational amplifier (OP) with a feedback resistor (R5). One side (R1, R2) of the bridge consists of piezoresistive resistors. The d.c. operating point is adjusted to a predetermined value by trimming the resistances and the sensitivity is adjusted by trimming the feedback resistor. Only one (R2) of the piezoresistors is exposed to the measurement pressure. USE/ADVANTAGE - For i.c. engine ignition chamber pressure measurement. Entire pressure sensor including evaluation circuit can be implemented on single hybrid.

Variable capacity type swingable compressor

Abstract: PURPOSE:To secure the degree of freedom in control by controlling the pressure in an intermediate chamber to an arbitrary pressure between the internal pressure of a discharge chamber and the internal pressure in a suction chamber by opening/closing- controlling the second controller and shifting the valve opening/closing operation point of the first controller according to the pressure in the intermediate chamber. CONSTITUTION:An intermediate chamber 16 communicates to a discharge chamber 15 through an orifice 60 formed in a communication passage 210, and communicates to a suction chamber 14 through a communication passage 220 and an electromagnetic flow-rate control valve (second controller) 70. The control valve 70 is in opening during electric conduction, and the valve opening area is set so that the discharge gas flows into the suction chamber 14 from the intermediate chamber 16, with equal flow-rate to the max. discharge gas introducing quantity which flows into the intermediate chamber 16 through the orifice 60 from the discharge chamber 15. Therefore, the intermediate chamber 16 can be set to an arbitrary pressure from the discharge chamber pressure to the suction chamber pressure by controlling the time ratio between the electric conduction time and the electric nonconduction time of the control valve 70 and controlling the substantial valve opening degree of the control valve 70.

Influence of chamber pressure on hydrogen bonding configurations in a-SiGe: H films prepared by photo-CVD

Abstract: Hydrogenated amorphous silicon-germanium (a-SiGe:H) thin films have been deposited by the process of mercury sensitized photo-CVD method from a mixture of silane and germane gases. The growth processes of a-Si:H and a-Ge:H films have been studied at different chamber pressures and from these data optimum pressures for the deposition of a-SiGe:H films have been selected. The variations of the electrical and structural properties of these films with optical band gap have been studied with films deposited at different chamber pressures. The properties of a-SiGe:H films have been found to be better at lower chamber pressure and the data is interpretated on the basis of changes in hydrogen bonding configuration with pressure.

Growing method for silicon nitride fluoride film

Abstract: PURPOSE:To form at a high growing velocity by previously depositing a nitride film on the inner face of the reaction chamber of a plasma vapor growing apparatus with SiH4-NH3-N2 gas as material gas, and plasma vapor growing a silicon fluoride nitride film on a substrate in the chamber. CONSTITUTION:A nitride film having a predetermined thickness is grown and deposited on the inner wall of a reaction chamber by applying plasma by means of a plasma exciting vapor growing method with 180sccm of SiH4 gas, 600sccm of N2 gas and 72sccm of NH3 gas as material gases under 300mTorr of chamber pressure at 3.0A of parallel flat plate electrode current. Thereafter, in the cham ber, plasma is generated under the conditions of 300mTorr of pressure of the mixture gas of 45sccm of SiF4 gas, 300sccm of N2 gas and 90sccm of H2 gas, 3.0A of parallel flat plate electrode current and 300 deg.C of substrate temperature, and a silicon fluoride nitride film is grown and formed on the substrate. Thus, a film having a uniform thickness is stably formed at a high growing velocity.

Combustor design and analysis using the ROCket Combustor Interactive Design (ROCCID) Methodology

Abstract: The ROCket Combustor Interactive Design (ROCCID) Methodology is a newly developed, interactive computer code for the design and analysis of a liquid propellant rocket combustion chamber. The application of ROCCID to design a liquid rocket combustion chamber is illustrated. Designs for a 50,000 lbf thrust and 1250 psi chamber pressure combustor using liquid oxygen (LOX)RP-1 propellants are developed and evaluated. Tradeoffs between key design parameters affecting combustor performance and stability are examined. Predicted performance and combustion stability margin for these designs are provided as a function of the combustor operating mixture ratio and chamber pressure.

Load pressure compensation type logic valve control circuit

Abstract: PURPOSE:To aim at improvement of the stroke control accuracy of a logic valve by adding the spring chamber pressure of the logic valve to a pilot spool opposite against its spring force and adding the load pressure of an inlet chamber in a direction same as the spring force. CONSTITUTION:The pressure of the spring chamber 5 of a logic valve 1 is introduced to a pressure chamber 9 opposite to the spring 12 of a pilot spool 16 via detecting passages 7, 7b, the load pressure of an inlet chamber 2 is introduced to a pressure chamber 13 via a detecting passage 14, a spool 18 is urged in a direction same as the spring 12, the secondary pressure is not generated when the operation lever of a pilot valve 19 is at a neutral position and the spool 16 is abutted to a seat 17. The operation lever is operated, the secondary pressure is introduced in an oil chamber 10, a taper portion 16a is slightly floated from the seat 17, the pressure in the spring chamber 5 is flowed via an oil chamber 8 to an oil discharge chamber 11 side and the logic valve 1 is moved with resistance to a spring 6 due to differential pressure between the inlet port 2 and the spring chamber 5 via an orifice 22 and balance with the secondary pressure. Thus, the stroke control of the logic valve can be achieved accurately.

Relay valve control chamber pressure control method - switching changeovervalve before blocking valve when load circuit pressure rises

Abstract: A relay valve (13) control chamber (23) pressure control method involves switching a change-over valve (30) temporarily into its operating position (30b) before a blocking valve (29) is switched into its operating position (29b) in the event of a rise in the pressure in the load circuit. In the event of a limitation of the pressure drop in the load circuit the change-over valve is switched into its rest position (30a) before the blocking valve is switched into its operating position. USE/ADVANTAGE - Prevents excessive operating pressure increase in load circuit, e.g. brake installation of commercial vehicle.

A two-phase fluid volume compensation chamber for an electric ventricular assist device.

Abstract: A volume compensation chamber is a device used to reduce large pressure fluctuations created in electric ventricular assist devices during the emptying and filling of the blood sac. In this study, the effect of motor casing pressure variation (pressure swing) on the performance of the Penn State electric ventricular assist device (EVAD) was investigated. Design criteria were established for the maximum pressure swing tolerated by the EVAD and the optimal mean chamber pressure at which to operate. At the chosen mean chamber pressure of -15 mm Hg, it was found that pressure swing should be maintained below 45 mm Hg. A two-phase fluid volume compensation chamber was developed that reduced the pressure swing enough to ensure adequate pump performance. The device consists of a metal chamber with a high-heat-flux porous coating applied to the inside surface. The chamber uses Freon as the working fluid and is isolated from the EVAD by a metal bellows. It was found that the high-flux coating significantly reduces the pressure swing, in some cases by as much as 50% when compared with an identical chamber with no coating. In the coated chamber the pressure swing was maintained between 22 and 30 mm Hg at a beat rate of 60 beats/min, for a wide range of Freon volumes (4-38 ml). Even at 100 beats/min the pressure swings obtained with the coated chamber are well within an acceptable range.