Showing papers on "Chamber pressure published in 1982"

Bearing chamber pressurization system for a machine

Abstract: A bearing chamber pressurization system for a ducted fan gas turbine engine uses fan delivery air at relatively low pressure and temperature for bearing chamber pressurization. In order to avoid the possibility of a flow reversal in the pressurization air when the fan speed is reduced, a second higher pressure air supply from the core engine is made available under the control of a valve and pressure sensing device, and which comes into operation when the ratio of the bearing chamber pressure and the supply pressure reaches a pre-determined minimum.

Experimental Investigation of Pressure Oscillations in a Side Dump Ramjet Combustor

Abstract: A two-inlet, side dump ramjet combustor configuration was tested in a connected-pipe setup using uncooled and uninsulated chamber walls. High amplitude combustion induced pressure oscillations were observed during most test conditions with a predominant frequency of around 300 Hz. Special efforts were made to relate the oscillations to longitudinal acoustic modes. A simplified no flow, uniform temperature acoustic cavity prediction method (NASTRAN) was utilized to model the longitudinal acoustic modes. This model was verified via room temperature laboratory tests using the actual test hardware and a loudspeaker as an input forcing function to excite the acoustic modes. During combustion tests, the measured oscillation modes were tentatively identified as second or third longitudinal modes or a "bulk" mode, depending on the test conditions.

Pressure measurement in fluid pump systems

Abstract: A fluid pump for use in high performance liquid chromatography having a piston movable in a chamber for drawing fluid into, pressurizing, and delivering the pressurized fluid from the chamber. A pressure transducer in the chamber derives a pressure output signal indicative of chamber pressure. Means is provided for correcting offset errors in the pressure output signal.

In-service test valve

Abstract: Disclosed is an in-service test valve and system. The in-service test valve includes a body having a first chamber with a relatively small diameter bore and second chamber axially spaced apart from the first chamber and having a relatively large diameter bore. An imperforate shuttle is slidingly mounted in the valve body and includes a first piston slidingly sealingly mounted in the first chamber bore and a second piston slidingly sealingly mounted in the second chamber bore. An in-service inlet is provided in the valve body for introducing in-service pressure into the first chamber to apply sensing pressure to the first piston and urge the shuttle toward the second chamber. A test inlet is provided for introducing test pressure into the second chamber to apply test pressure to the second piston to urge the shuttle in the direction of the first chamber. A check valve is provided in the valve body for allowing communication of test pressure to the first chamber when test pressure is greater than first chamber pressure. A valve operated by the shuttle is provided for isolating the in-service inlet from the first chamber when test pressure is applied. An outlet is provided in the valve body for communicating pressure within the first chamber exterior of the valve.

Development of more efficient airgun arrays: theory and experiment*

Abstract: Source strength of an airgun array may be increased by: — utilizing higher pressure, — increasing total array volume, — employing more guns, — improving gun efficiency One measure of gun efficiency is “specific source strength”, Pa*, defined as source strength per unit quantity of air used Typical units are MPa m/l Most developments are directed toward increasing gun pressure and/or gun volume to increase source strength of the array These efforts require that more air compressors be installed onboard the ship Consequently, a larger ship may be needed for the additional compressors, guns, and auxiliary equipment A development program was initiated in 1976 to increase source strength of the array without using a larger ship New guns were designed and built—one for 414 MPa and 737 liter (6000 psi/450 in3) operation and another with 138 MPa and 492 liter (2000 psi/300 in3) capability Experiments were conducted with these new guns (and existing guns) over a range of pressures from 138 to 414 MPa (2000 to 6000 psi) Design of the new guns was aided by a mathematical model The model relates physical dimensions of the airgun to acoustic pressure in the water It consists of four nonlinear differential equations relating — shuttle motion, — bubble pressure, — chamber pressure, — bubble radius The last equation is the “free-bubble-oscillation equation” and represents the ideal case of a pressurized bubble released instantaneously in water The three other equations modify this ideal case; the four equations together model an airgun of the type manufactured by Bolt Associates, Inc

Fluidic valve combination

Abstract: A fluidic valve assembly for use with a low pressure hyperbaric chamber, a pressurized source of oxygen, a flow control unit in an oxygen feed line in fluid communication with the chamber, an exhaust valve in fluid communication with the chamber, said exhaust valve being in fluid communication with the oxygen feed line whose pressure maintains the exhaust valve in the closed condition, a one way valve in a first pressure line in fluid communication with the chamber set to allow flow from the chamber at a prescribed pressure, a second pressure line in fluid communication with the chamber, said fluidic valve assembly comprising an inlet flow valve having an inlet connected to the oxygen source and an outlet fluidly connected to the oxygen feed line in communication with the chamber, a closure for closing said outlet, a power assembly connected to the first pressure line for closing said closure when fluid flows in the first pressure line upon the attainment of the prescribed chamber pressure, a first vent for venting the oxygen feed line to atmosphere, the aforesaid power assembly simultaneously opening the first vent to atmosphere with the closing of the closure for the outlet of the inlet flow valve, the decrease of pressure in the oxygen feed line allowing the exhaust valve to open to vent the chamber to atmosphere, a second vent for venting the power assembly, and a pressure assembly connected to the second pressure line in fluid communication with the chamber for controlling the second vent in response to chamber pressure wherein upon the loss of pressure in the chamber, the pressure in the aforesaid pressure assembly decreases to allow the second vent to open to vent the power assembly to atmosphere whereby the oxygen pressure from the timer will force open the closure for the outlet of the inlet flow valve and simultaneously close the first vent to open fluid flow between the outlet and the chamber through the oxygen feed line to commence a new cycle.

Respirator for use in pressure chambers

Abstract: The respirator for use in pressure chambers serves to ventilate patients in therapeutic areas or in diver pressure chambers at diverse pressures. All its operations are effected pneumatically. The selected (a) ventilating volume supplied to the patient must remain constant (in operating liters) and the selected (b) breathing rate must be maintained. For meeting condition (a), the respirator contains a known pressure ratio regulator working on the double-diaphragm principle, and for meeting condition (b) it contains a frequency stabilizer. The frequency stabilizer contains in a housing a stepped piston moved by the chamber pressure against a spring, forming two volumes. The ratio of the free piston surfaces to each other determines the breathing time ratio. The volumes, adjusted by the chamber pressure over the height, determine the breathing rate together with the gas amount/time unit set by a precision adjusting valve. A varying chamber pressure for the controls has no effect on the breathing time ratio and the breathing rate. The respirator is equally suitable for use in therapeutic pressure chambers, like hyperbaric oxygen chambers, and for diver pressure chambers.

Vacuum distillation of liquid metals: Part II. Photographic study

Abstract: Photographs of melt surface conditions and gas flows were taken during experiments which examined vacuum refining of melted steel scrap. The photographs illustrate the retarding effects of surface films on rates of copper and tin evaporation. The photographs also protray the characteristic variation in vapor flow pattern caused by altering chamber pressure. This was in agreement with the behavior predicted by the distillation model developed in Part I. It was also observed that vapor condensation may be a major problem area for industrial application of this process. Several solutions for this are suggested.

Test verification of LOX/RP-1 high-pressure fuel/oxidizer-rich preburner designs

Abstract: Two fuel-rich and two oxidizer-rich preburner injectors are tested with LOX/RP-1 in an investigation of performance, stability and gas temperature uniformity over a chamber pressure range from 1292 to 2540 psia. Fuel-rich mixture ratios range from 0.238 to 0.367 and oxidizer-rich mixture ratios range from 27 to 48, and carbon deposition data are collected by measuring the pressure drop across a turbine simulator flow device. The oxidizer-rich testing demonstrates the feasibility of oxidizer-rich preburners, indicating equilibrium combustion as predicted, and the measured fuel-rich gas composition and C-asterisk performance are in excellent agreement with kinetic model predictions indicating kinetically-limited combustion.

Hydraulic brake with pressure control - has valve plunger sliding in piston and subjected to controlled chamber pressure

Abstract: The hydraulic brake system has a wheel cylinder with pistons acting on leading and trailing shoes, together with a pressure-control valve separating a first chamber applying uncontrolled pressure to the first piston from a second one applying controlled pressure to the second one This valve is shut by movement of a valve plunger under pressure in opposition to a preloaded spring The first chamber is annular, enclosed between an annular surface of the first brake piston, and a stationary sealing ring insert The valve plunger slides in the first piston and forms a sealed joint with it, being subjected to the pressure in the second chamber The spring is supported by the first piston

Rotary type slave actuator - has vane operated by fluid pressure selectors and pressure limiter formed by ball valve

Abstract: The rotary actuator has a sealed volume formed by a cylindrical wall of a sleeve and two flanges blocking the ends. This space has a stop on one flange and a mobile vane on a rotor shaft. The stop works with the vane and wall to form sealed chambers for fluid under pressure. One or other of the chambers (304,305) communicates with selectors and/or pressure limiters (401,405,405',406') with feed holes between seals to the flanges and rotor shaft. The pressure limiter is a ball (401) under differential chamber pressure, moving between seats in the feed.

Thrust chamber technology for advanced earth-to-orbit rocket engines

Abstract: Studies of advanced earth-to-orbit vehicles have shown the need for new oxygen-hydrocarbon rocket engines. These advanced engines are characterized by high chamber pressures (to 6000 psia), reusability, and high performance. The propulsion technology necessary to meet these requirements is now being defined. This paper examines thrust chamber cooling and reuse, ignition, performance, and combustion stability in the light of recent engine design studies and the results of tests with oxygen/RP-1 at pressures up to 2500 psia. It is concluded that satisfactory ignition, performance, and stability should be achievable without requiring major technology advancements. The results of engine regenerative cooling studies with oxygen, methane, propane, RP-1, and hydrogen as coolants are presented. The studies indicate that engine operation above approximately 4000 psia chamber pressure will require supplemental mass transfer cooling or the development of improved regenerative cooling techniques.

Performance of the AEDC Mark I Aerospace Environmental Chamber without Oil Diffusion Pumping

Abstract: : The 40- by 80-ft MK-I Aerospace Environmental Chamber was pumped down to a pressure of 2 x 10 to the minus 6th power torr in order to verify an operational mode that could maintain test conditions without the use of oil diffusion pumping. Mechanical pumps rough pumped into the micron (1 to 10.0 x 10 to the minus 3rd power torr) range, and the cryogenic arrays reduced the pressure to 2 x 10 to the minus 6th power torr and maintained it for 24 hours. The pumpdown without the use of diffusion pumping is often dictated by test requirements for exceptional cleanliness. After pumpdown, inbleeding of CO2, H2, and N2 affected chamber pressure as a function of gas species and inflow rate. The time for the liquid nitrogen and gaseous helium-cooled cryosurfaces to cool down and warm up was determined as an aid to test planning. Because several modifications to the cryopumping geometry had been made since the chamber was initially placed into service, it was considered important to verify the MK-I performance. It is concluded that the mechanical roughing/cryogenic pumping method of operation is satisfactory for simulation of conditions where the outgassing is relatively small or consists of gases with low vapor pressure at liquid nitrogen temperature (i.e., CO2 or H2O).

Etch end point detector in reactive ion etching systems

Abstract: As etching progresses from one layer of material to another in reactive ion etching systems, the partial pressures of the reaction chamber gas components change. In constant pressure reactive ion etching systems, changes in chamber pressure are corrected by changes in the etchant species flow rate into the reaction chamber. By monitoring flow rate, information is obtained which may be used to identify points where partial pressures change, and latter may, in turn, be used to derive etching points in the material being etched.

Method for controlling differential pressure between bells of blast furnace

Abstract: PURPOSE:To stably open or close a small bell during charging of raw materials by providing a small bell chamber pressure take-out chamber between a pressure equalizing gas introducing valve of a flow passage feeding a pressure equalizing gas to a small chamber and the small chamber, and controlling the differential pressure between bells by the pressures taken out from this and a large bell chamber pressure equalizing part CONSTITUTION:The pressure taken out from a small bell chamber pressure take- out part 13 provided on the small bell chamber 4 side of a pressure equalizing gas introducing valve 11 of a flow passage 9 for pressure equalizing gaseous nitrogen introduction and the pressure taken out from a take-out part 14 for large bell chamber pressure directly provided in a large bell chamber 6 are inputted to an interbell differential pressure detector, whereby the differential pressure between the bells is controlled Thereby, the introduction of the gas for the purpose of eliminating the differential pressure between the bells is accomplished surely at the charging of raw materials

Gas etching system including end point detection

Abstract: A gas etching system includes a plasma etching chamber (1), a pressure sensor (9) adapted to sense the pressure within the chamber (1) and a constant displacement vacuum pump (2) adapted to extract gases from the chamber (1). The etchant gases entering the chamber (1) have their flow regulated by a feedback loop which includes the pressure sensor (9). Changes in the chemical composition within the chamber (1) which occur in time proximity to the end point of etching affect the chamber pressure and are detected as variations in the gas flow rates. These variations are depicted visually on a strip chart recorder (12). The system detects the end point of etching with high sensitivity.

Non-dispersive IR gas analyser beam receiver - eliminates spectral interference by using non-selective absorption wire elements

Abstract: A radiation receiver for a non-dispersive, infrared gas analyser with a periodic beam interruption device consists of two gas chambers (1,2) in series in the beam path. A pneumatic-to-electric transducer (3) converts the chamber pressure difference into an electrical signal. It eliminages the errors encountered when gas components in the mixture being analysed have absorption bands which interfere with measurement component absorption bands. This is achieved by partially blocking the cross-section of the first or second chamber with them, low thermal inertia elements (8) which absorb the incident radiation non-selectively. The elements may be in the form of blackened wires, or a single wire element may be used. They are placed in the first or second chamber according to the type and degree of spectral interference. (Specification printed 7.1.82).

Plasma etching apparatus and method including end point detection

Abstract: A gas etching system includes a plasma etching chamber (1), a pressure sensor (9) adapted to sense the pressure within the chamber (1) and a constant displacement vacuum pump (2) adapted to extract gases from the chamber (1). The etchant gases entering the chamber (1) have their flow regulated by a feedback loop which includes the pressure sensor (9). Changes in the chemical composition within the chamber (1) which occur in time proximity to the end point of etching affect the chamber pressure and are detected as variations in the gas flow rates. These variations are depicted visually on a strip chart recorder (12). The system detects the end point of etching with high sensitivity.

Chamber pressure appts. probe with pressure dependent resistance - pref. with the probe resistances protected by silicone coating

Abstract: Device for measuring pressure within an enclosure is based on one or more pressure sensitive resistance elements mounted on a probe and connected to a suitable meter The resistance is made of a blend of conductive and non-conductive matl and is connected across opposite sides of a Wheatstone bridge circuit Over a pressure range of eg 0-400 bars responds with up to 20% signal level change, compared with about 2% for a conventional strain gauge Pref the probe resistances are protected from damage, moisture etc by a coating of silicone resin Suitable resistances are commercially available, eg hot-moulded type EB-RcR20 from Allen-Bradley