Showing papers on "Chamber pressure published in 1986"

A comparison of the thermocouple psychrometer and the pressure plate methods for determination of soil water characteristic curves

Abstract: SUMMARY The thermocouple psychrometer method and the pressure plate apparatus method werecompared for determining the energy status of soil water, and it has been shown that the resulting soil water characteristic curves might differ significantly. Ψt determined by the psychrometer method was always higher than Ψm, determined with the pressure plate method. Thus, the soil water characteristic curve determined with the pressure plate method may not represent the true condition of soil water, and the actual matric potential may be considerably higher than that assumed from the applied chamber pressure. This suggests the need for careful examination of the pressure plate method for determining the soil water characteristic curve.

Augmented carbonaceous substrate alteration

Abstract: Accurately altering a precisely located site on a substrate by: (a) providing a vacuum chamber; (b) providing an energy beam; (c) providing a source of a hydrocarbon and a conduit extending between the source and the chamber, the hydrocarbon being capable of being adsorbed in the substrate and of interacting with the energy beam to alter the substrate; (d) positioning the substrate in the chamber to be exposed to hydrocarbon delivered by the conduit; (e) introducing into the conduit a carrier having a vapor pressure above the vapor pressure of the hydrocarbon, the carrier being in vapor form under conditions existing in the conduit and having a bulk velocity that transports the hydrocarbon by molecular collisions into the chamber, the hydrocarbon being adsorbed on the surface of the substrate, free carrier molecules being drawn off sufficiently rapidly to maintain low pressure in the chamber; and (e) while maintaining the low chamber pressure, directing the energy beam to the site in the presence of the absorbed hydrocarbon, in a manner to convert the hydrocarbon to a coherent carbonaceous deposit of predetermined desired form, adherent to the substrate at the site to render the site opaque. Most preferably, a focused ion beam is used to repair an opaque defect in a photolithographic mask.

Fluid flow sensor having multiplying effect

Abstract: A sensor has two independent pressure chambers, each of which is in fluid communication through a plurality of relatively small passages to the flow within a duct; the passages for the first chamber being directed upstream, the passages for the second chamber being directed otherwise than upstream, usually downstream. The chambers are arranged so that their axes are parallel to each other, with the axis of the first chamber upstream of the axis of the second chamber. Depending upon the profile of the sensor, the dynamic pressure and changes therein are a constant multiplier function of the first chamber pressure minus static pressure. The constant multiplier is greater than 1.0, and is constant for a given sensor across a wide variation of measured pressures. When the profile of the sensor is essentially cruciform, with upwardly and downwardly extending wings, the multiplier effect may be in the order of 3.5 to 5.0, thereby permitting very low differential pressures to be detected and measured.

Internal stress in ion beam sputtered molybdenum films

Abstract: Stress in molybdenum films deposited by ion beam sputtering has been studied as a function of deposition parameters, such as accelerating voltage, incident angle, and chamber pressure. It has been found that the physical properties of deposited molybdenum films controlled primarily by the ion beam accelerating voltage and substrate orientation with respect to the ion beam. For films deposited at near normal incidence, measured stresses are highly compressive (2–5 GPa) and increase almost linearly with the accelerating voltage (600–1500 V). Under these conditions, deposited molybdenum films exhibit low resistivity and high optical reflectance. As the substrates are rotated to near grazing incidence, measured stress is either negligible or slightly tensile and are almost independent of accelerating voltage. The extremely high resistivity and low reflectance measured indicates the poor quality of the deposited film at grazing incidence. No significant effect was observed when the chamber pressure was varied ...

Vacuum chamber pressure effects on thrust measurements of low Reynolds number nozzles

Abstract: Tests were conducted to investigate the effect of vacuum facility pressure on the performance of small thruster nozzles. Thrust measurements of two converging-diverging nozzles with an area ratio of 140 and an orifice plate flowing unheated nitrogen and hydrogen were taken over a wide range of vacuum facility pressures and nozzle throat Reynolds numbers. In the Reynolds number range of 2200 to 12,000 there was no discernable viscous effect on thrust below an ambient to total pressure ratio of 1000. In nearly all cases, flow separation occurred at a pressure ratio of about 1000. This was the upper limit for obtaining an accurate thrust measurement for a conical nozzle with an area ratio of 140.

Finite-element application to rocket nozzle aeroelasticity

Abstract: The trend in rocket technology is toward thinner, larger expansion ratios and more flexible exit cones. Hence, susceptibility to aerodynamically induced flutter has been and is a concern to both designer and analyst. The objective of this investigation is to develop an analytical tool for treating the aeroelastic stability of thin, truncated conical shells subjected to internal supersonic flow, with particular application to rocket nozzle structures. Stiffness, mass, and damping matrices are derived for an axisymmetric conical shell frustum finite element. The matrix equation of motion for a prescribed circumferential harmonic is developed and an eigenproblem formed from which flutter instability is deduced by tracking complex eigenvalue part variation with increasing dynamic pressure. Several check problems are considered to validate the various aspects of the analytics and computer code. Following this, the flutter analysis of a gas-deployed skirt, a typical rocket nozzle element, is presented to illustrate its application to rocket nozzle hardware. For this particular case, the analytical results indicate flutter at a motor chamber pressure well above the operating chamber pressure.

Low fluid level warning system

Abstract: A low fluid level warning system (100) is adapted for use with a conventional oil circulation and low pressure warning system in an engine-driven vehicle. Oil from a crankcase reservoir (102) is pumped through an inlet conduit (110) to varius engine supply lines (116). A portion of the oil is also pumped into an enclosed chamber (124). A pressure sensor diaphragm (132) and switch contacts (130) sense the chamber pressure and illuminate a warning lamp (142) when the pressure is below a predetermined pressure. A drain conduit (160) extends from the bottom of the chamber at the bottom of the oil reservoir (102). A vent conduit (150) extends from the top of the chamber to a predetermined level in the reservoir (102). If the oil in the reservoir (102) is below the predetermined level, the chamber (124) drains completely when the engine is turned off. If the oil in the reservoir (102) is above the predetermined level, the chamber oil does not drain. When the engine is next started, the duration of time (short or extended) necessary for the chamber pressure to build up, and extinguish the warning lamp, is indicative of whether the oil in the reservoir is above or below the predetermined level.

Experimental investigation of combustion efficiency of air-augmentedrockets

Abstract: This paper reports the results of an experimental study concerned with the mixing and combustion processes in air-augmented rockets. A combustor assembly consisting of the primary rocket and the secondary, constant-area combustion chamber were utilized to simulate a typical tactical missile. Several different configurations of the primary chamber rocket nozzles have been designed and tested in order to evaluate the mixing in the afterburning combustion chamber. On the basis of the experimental results, the secondary combustor using the subsonic primary nozzle with multiple jets has been shown to achieve the highest combustion efficiency, about 30% greater than that of the single-sonic or supersonic nozzles. Instrumentation was also provided for measurements of the pressures and velocities of the ducted flow. These measurements provide a basis for an understanding of the combustion process.

Liquid oxygen cooling of high pressure LOX/hydrocarbon rocket thrust chambers

Abstract: An experimental program using liquid oxygen (LOX) and RP-1 as the propellants and supercritical LOX as the coolant was conducted at 4.14, 8.27, and 13.79 MN/sq m (600, 1200, and 2000 psia) chamber pressure. The objectives of this program were to evaluate the cooling characteristics of LOX with the LOX/RP-1 propellants, the buildup of the soot on the hot-gas-side chamber wall, and the effect of an internal LOX leak on the structural integrity of the combustor. Five thrust chambers with throat diameters of 6.6 cm (2.5 in.) were tested successfully. The first three were tested at 4.14 MN/sq m (600 psia) chamber pressure over a mixture ratio range of 2.25 to 2.92. One of these three was tested for over 22 cyclic tests after the first through crack from the coolant channel to the combustion zone was observed with no apparent metal burning or distress. The fourth chamber was tested at 8.27 MN/sq m (1200 psia) chamber pressure over a mixture range of 1.93 to 2.98. The fourth and fifth chambers were tested at 13.79 MN/sq m (2000 psia) chamber pressure over a mixture ratio range of 1.79 to 2.68.

Refrigeration system including capacity modulation

Abstract: A refrigeration system adapted particularly for a vehicle air conditioning system and including a capacity modulation mechanism. A portion of the liquid refrigerant at the outlet of the condenser (18) is fed back to the suction chamber (106) of the compressor through the orifice (130) of a bypass valve (30). The valve is mounted on the compressor and is responsive to suction chamber pressure. As the evaporator temperature decreases, suction chamber pressure also decreases thereby opening the valve to meter a small amount of bypassed liquid refrigerant into the suction chamber of the compressor. A portion of the hot discharge gas may also be bypassed back into the suction chamber through the same valve (30) that meters the bypassed liquid refrigerant.

Anti-locking brake modulator with independent input and output solenoid actuated valves including check valve and pressure relief valve

Abstract: An anti-locking modulator for reducing braking pressure applied to brakes during anti-locking operation dependent upon pressure in a pressure chamber. An input solenoid valve supplies pressurized fluid to the control chamber and is weakly biased to be closed so that a reduction of pressure in the pressure chamber opens the input solenoid valve for repressurization. Electrical activation of the input solenoid positively closes the input solenoid valve. An output solenoid connecting the pressure chamber to near atmospheric pressure valve is biased against the chamber pressure to be closed to thereby prevent overpressurization. Electrical activation of the output solenoid opens the output solenoid valve, thereby depressurizing the pressure chamber.

Turbine shaft fuel pump

Abstract: A fuel pump within the main shaft of a turbine engine comprises a fuel tube extending axially through the shaft, a first shaft wall and the second shaft wall spaced apart from each other at one end of the tube to define a flow passage therebetween, a plurality of substantially radially aligned vanes extending across the passageway, an annular cavity in fluid communication with the outlet of the vaned passageway and a plurality of circumferentially spaced injector nozzles in fluid communication with the annular cavity and opening into the combustion chamber of turbine engine. The pump vanes impart sufficient energy to the fuel to overcome friction losses in the injector nozzles and to overcome the pressure within the combustor chamber. In addition, the energy imparted to the fuel forms a fuel barrier which separates the combustor chamber pressure from pressure within the fuel tube. Fuel is delivered to the fuel tube by pumping and metering means which can be downsized from previously known fuel pump mechanisms since it only needs to meter a desired amount of fuel and provide pressure only to overcome friction losses in the flow path up to fuel tube within main shaft of the turbine.

Effect of pressure on the sublimation rate of ice.

Abstract: This paper considers the effect that chamber pressure has on the sublimation rate of ice and primary drying time. It is shown that the effect of increasing the chamber pressure results in a decrease rather than an increase in the sublimation as was previously reported. The increase in chamber pressure can increase the heat transfer by the wall of the container and result in an increase in the sublimating area. The increase in the sublimating area may more than offset the decrease in the sublimating rate and lead to a reduction in the primary drying time. Upper and lower chamber pressure limits for the lyophilization process are considered.

Assessment of Fiber Strength in a Urinary Bladder by Using Experimental Pressure Volume Curves: An Analytical Method

Abstract: In the present study, an analytical method is developed to deduce the constitutive equations of fibers embedded in a thick shell from the time-variant pressure volume curves obtained by experimental procedures. It is assumed that the spherical shell under consideration is composed of a fiber reinforced material and undergoes radial deflection, modeling the behavior of some biological shells such as urinary bladder. The fiber stress is expressed as a function of fiber strain, rate of strain and the degree of biochemical activation. The function form is chosen such that equations of mechanical equilibrium can be integrated analytically to yield chamber pressure as a function of chamber volume, time rate of change of volume and activation. Arbitrary coefficients appearing in the fiber stress-equation are also present in the resultant time-variant pressure-volume relation. These coefficients can be determined by curve-fitting commonly used clinical data such as cystometry measurements.

On Performance Evaluation of a New Liquid Propellant

Abstract: A blend of 3-carene and cardanol in 70:30 weight proportion exhibits synergistic hypergolic ignition with red fuming nitric acid (RFNA) as oxidizer. Attempts have been made to evaluate this new propellant by theoretical calculationof performance parameters and verification of the results by static firing of a 10 kg thrust rocket motor around 20 atmosphers of chamber pressure. At an oxidizer-to-fuel weight ratio (O/F) of 3.34 (RFNA used had 21% N204 and 5% by weight of concentrated sulphuric acid as catalyst), the propellant produced a reasonably smooth pressure-time curve with an ignition delay of 35 milliseconds. The theoretical characteristic velocity value matched well with the experimental. No carbon residue was left in the rocket motor after firing. Specific impulse (theoretical) of the propellant has been found to be 223.8 seconds at chamber pressure, 20 atmos and exist pressure, 1 atmos.

Method for removing resist

Abstract: PURPOSE:To enhance the removal speed of a used photoresist film by bringing the resist into contact with gaseous oxygen pressurized to 2-3 atm under irradiation of UV rays. CONSTITUTION:The treatment chamber is fed with oxygen through an oxygen inlet 2 and a waste gas is exhausted through a gas outlet 3. In the chamber 1, UV lamps 4 irradiate UV rays of 184.9 and 253.7 nm wavelength on a wafer coated with the used resist 6 on its surface. The resist 6 is can be removed at a practicably satisfactory speed without impairing the substrate wafer 5 by treating it at a wafer temp. of 240-260 C, arranging the distance between the wafer 5 and the lamps 4 to 3-5mm, and maintaining the internal chamber pressure of 2-3 atm.

Evaluation of Cold Isostatic Pressing of High-Pressure Thrust Chamber Closeout

Abstract: The objective of this project was to investigate new fabrication methods and design techniques that potentially reduce fabrication time and cost, as well as increase rocket thrust chamber life. For these purposes, the authors developed the cold isostatic pressing (CIP) forming method, based on powder metallurgy. Using the CIP forming method, a very compliant closeout was easily obtained while sustaining sufficient bonding strength between the copper liner and the closeout, and providing perfect sealing of coolant channels. A metallurgical test was performed before the fabrication of a trial combustion chamber to determine the forming conditions of the sintered closeout that would meet the required design conditions. The trial combustion chamber was then made to withstand a design combustion pressure of 15 MPa and a thrust level of 10 kN. Combustion tests were conducted at chamber pressures up to 9 MPa for 28 runs to confirm the reliability of the CIP-formed chamber. A preliminary analysis was then made which also demonstrated that a thrust chamber with a compliant, sintered alloy closeout would have a longer life capability than one with a stiffer, electroformed nickel closeout.

Slip control device for lockup torque converter

Abstract: PURPOSE:To reduce the shock due to a speed change during a slip control by increasing the pressure in a lockup control chamber when a speed change is carried out during a slip control. CONSTITUTION:When the speed change of an automatic speed change gear is carried out during a slip control, a lockup control chamber pressure PL once falls. This pressure fall is detected by a pressure switch 36, and further a solenoid valve 31 is actuated by the action of the pressure switch 36. A line pressure Pl is released by the actuation of the solenoid valve 31 to reduce the pressure acting on one end of the spool 25e of a region judging valve 25, and further the port 25a communicating with a passage, which supplies a lockup control chamber pressure, is communicated with a converter chamber 17 via a port 25e. Thus, the pressure in a lockup control chamber 18 increases to increase the slip degree of a lockup clutch 16, and the occurrence of shock due to a speed change can be reduced.

Oil free displacement type hydraulic machine

Abstract: PURPOSE:To reduce a gas temperature in a discharging area effectively by a method wherein gas, having a temperature lower than the discharging gas temperature upon full load operation, is blown off into the discharging area including a discharging chamber and a compression chamber, communicated to the discharging chamber at all times. CONSTITUTION:During effecting no-load operation, in which a suction chamber valve 5 is closed and a discharging chamber releasing valve 15 is opened to make both of a suction chamber pressure and the discharging chamber pressure less than respective pressures upon full-load operation, a part of gas of rear flow of an after cooler 8 is blown off into the discharging area including the discharging chamber and the compression chamber. According to this constitution, the low-temperature gas is blown off into the discharging area, whose temperature is to be reduced, without passing through the compression chamber, therefore, the pouring gas will never generate a compression heat due to the compression and the gas temperature in the discharging area may be reduced effectively.

A model-based system for assessing ventricular chamber pressure-volume-dimension relationship: regional and global deformation.

Abstract: A system has been developed for measuring and relating in a non-beating isolated canine left ventricle dynamic changes in chamber pressure, volume, diameter, regional segment length, and wall thickness. The measurement system consists of a pulsatile blood pump whose stroke-volume and frequency can be adjusted selectively. The external pump system is used as a primary means for controlling instantaneous intraventricular volume. The relationship between left ventricular volume change, intraventricular pressure, minor axis diameter, and regional dimensions were studied as a function of pump rate.In addition to the basic constitutive properties, this system provided the means for measuring and comparing regional and global pressurestrain relationship including the effect of strain rate and its relationship to viscoelastic myocardial muscle model. The dynamic relationship between global dimensions and regional dimensions, circumferential segment length, and wall thickness were also investigated. The instantaneous relationship between intraventricular pressure resulting from periodic oscillations of chamber volume, including minor equator diameter, wall thickness, and regional segment dimensions were plotted and fitted to an exponential pressure-strain model, assuming a quasi-static large deformation. The observed difference between global and regional pressure-dimension strain stiffness coefficients can be attributed in part to basic constitutive and geometric considerations and not necessarily to the complex anisotropic or heterogeneous nature of cardiac muscle properties. This methodology provides indices which appropriately characterize the regional and global left ventricular chamber deformation and stiffness.

Enhanced heat transfer combustor technology, subtasks 1 and 2, tast C.1

Abstract: Analytical and experimental studies are being conducted for NASA to evaluate means of increasing the heat extraction capability and service life of a liquid rocket combustor. This effort is being conducted in conjunction with other tasks to develop technologies for an advanced, expander cycle, oxygen/hydrogen engine planned for upper stage propulsion applications. Increased heat extraction, needed to raise available turbine drive energy for higher chamber pressure, is derived from combustion chamber hot gas wall ribs that increase the heat transfer surface area. Life improvement is obtained through channel designs that enhance cooling and maintain the wall temperature at an accepatable level. Laboratory test programs were conducted to evaluate the heat transfer characteristics of hot gas rib and coolant channel geometries selected through an analytical screening process. Detailed velocity profile maps, previously unavailable for rib and channel geometries, were obtained for the candidate designs using a cold flow laser velocimeter facility. Boundary layer behavior and heat transfer characteristics were determined from the velocity maps. Rib results were substantiated by hot air calorimeter testing. The flow data were analytically scaled to hot fire conditions and the results used to select two rib and three enhanced coolant channel configurations for further evaluation.

Apparatus and method for quantitative determination of chamber pressure in firearms

Abstract: An apparatus and method is described which enables one to determine the amount of chamber pressure produced by a cartridge in any firearm chambered for said cartridge. A plastic material of uniform size, consistency, and shape is attached to the outside of the cartridge case with translucent adhesive tape - the total thickness of the plastic material and tape being such that chambering of the cartridge is not significantly inhibited. During firing the pressure inside the cartridge case causes the plastic material to spread between the cartridge case and the tape as both are forced against the rigid surface of the chamber wall. The width of the plastic material is measured and is proportional to the amount of pressure generated during firing of the cartridge. The actual pressure in pounds per square inch is determined from a standard curve that relates the width of the plastic material to pounds per square inch.

Air pressure cylinder, especially a vehicle air pressure brake cylinder

Abstract: of EP01268741. Compressed air cylinder, particularly a compressed air brake cylinder for automotive brake systems, comprising a piston (2) shutting off an air-loadable working chamber (4) from an external pressure chamber (5) which can be vented to atmosphere via a venting device (14), and comprising a connecting bore (39, 39') bypassing the piston between working chamber and external pressure chamber, the passage in the said bore being monitored by a differential pressure valve which has a movable valve body (22, 22') loaded in the closing direction by the working chamber pressure against a spring force (35) and the pressure in the external pressure chamber, wherein the differential pressure valve has, viewing in the direction of flow, two series-connected, ring-shaped sealing points (36 and 37 or 49, 50 and 44, 48) of different diameter.

Abnormal differential pressure preventing apparatus for fuel cell

Abstract: PURPOSE:To effectively increase a surge function and to reduce the size of an abnormal differential pressure preventing apparatus for a fuel cell by providing a series combination of a volume chamber with the surge function and a liquid seal device between a fuel gas supply line and the atmosphere surrounding the body of the fuel cell. CONSTITUTION:In a normal operation, a liquid seal is effected between the atmospheric pressure and a fuel gas pressure as both the pressures are balanced while the water surface in a pipe 22 pressed down by the fuel gas pressure to a level of the height nearly equal to a water depth H. On a sudden increase in a fuel gas chamber pressure, the increment compresses the gas in a volume chamber 15a, which absorbs and relieves the increment. At the same time, the water surface level is lowered and a surge function is increased. On an additional sudden and large increase in the fuel gas chamber pressure, a part of the fuel gas is blown into the water through the open end of the pipe 22 to be discharged into the atmosphere. When a negative pressure is produced in the fuel gas chamber, the water overflown from the pipe 22 remains in the bottom of the volume chamber 15a and therefore there is no danger that the water is sucked into the fuel gas chamber.

Self-lapping type control valve device

Abstract: In a self-lapping type control valve device, a check valve is provided by means of a seal at the interface of the control piston diaphragm and a recess in which the diaphragm is connected to the valve body, the seal being effective to isolate a control chamber on one side of the control piston from a constant pressure chamber on the opposite side when the control piston is actuated in response to a reduction in the control chamber fluid pressure to initiate a brake application. This seal is displaced from a ridge at the opening of the recess with which the diaphragm is also engageable when actuation of the control piston occurs in response to a relatively large reduction of the control chamber pressure. The point of engagement of the diaphragm with the ridge defines a pressure area of the diaphragm subject to the control chamber/constant pressure chamber differential that is less than the pressure area of the diaphragm when the diaphragm is disengaged from the ridge due to a lesser pressure differential being effective to actuate the control piston. In so varying the effective pressure area of the diaphragm, the integrity of the seal effect of the check valve is assured at low as well as high brake levels.

Dual-throat thruster thermal model

Abstract: The dual-throat engine is one of the dual nozzle engine concepts studied for advanced space transportation applications. It provides a thrust change and an in-flight area ratio change through the use of two concentric combustors with their throats arranged in series. Test results are presented for a dual throat thruster burning gaseous oxygen and hydrogen at primary (inner) chamber pressures from 380 to 680 psia. Heat flux profiles were obtained from calorimetric cooling channels in the inner nozzle, outer or secondary chamber and the tip of the inner nozzle. Data were obtained for two nozzle spacings over a chamber pressure ratio (secondary/primary) range of 0.45 to 0.83 with both chambers firing (Mode I). Fluxes near the end of the inner nozzle were significantly higher than in Mode II when only the inner chamber was fired, due to the flow separation and recirculation caused by the back pressure imposed by the secondary chamber. As the pressure ratio increased, these heat fluxes increased and the region of high heat flux relative to Mode II extended farther upstream. The use of the gaseous hydrogen bleed flow in the secondary chamber to control heat fluxes in the primary plume attachment region was investigated in Mode II testing. A thermal model of a dual throat thruster was developed and upgraded using the experimental data.

Container accompanied with temperature change and pressure variation

Abstract: PURPOSE:To prevent breakage of a heat insulator and peeling-off of an interior finish, by applying a plate member for forming a pressure container on the inside of a reinforced concrete box, by laying the heat insulator on the inside of the plate member and by further applying the interior finish on the inside of the heat insulator. CONSTITUTION:A plate member 4 for forming a pressure container is applied to the inside of a reinforced concrete box 1. A polyurethane foamed material 5 is bonded on the inside of the plate member 4, and a water-proof coating layer 6 is formed on the outer surface of the polyurethane material 5. Further, an interior finish 10 is lined on the inside of the polyurethane foamed material 11. Although a slight gap 9 exists between the interior finish 10 and the water- proof covering layer 6, a gap 11 is formed to balance the pressure in the gap 9 with the chamber pressure. Thereby, it is possible to prevent peeling-off of the interior finish and damage of the polyurethane foamed material.