Showing papers on "Chamber pressure published in 1969"

Gas generator method and apparatus

Abstract: A gas generator method and apparatus comprising an enclosed pressure chamber having an exit port, a solid combustible material disposed in the chamber, a catalyst which can increase the decomposition rate of the combustible material which has been previously ignited, the catalyst being supported in the chamber adjacent to a surface of the combustible material. Means is provided for sensing the pressure in the chamber when the combustible material is decomposing and means is provided for moving the catalyst relative to the combustible material to maintain approximately constant chamber pressure during decomposition.

Injector response to strong, high-frequency pressure oscillations.

Abstract: Liquid propellant rocket injectors response to HF chamber pressure oscillations using one dimensional model

An investigation of the swirling flow in a spinning end-burning rocket

Abstract: The purpose of this study was to determine the swirling flowfield which develops at various spin rates in the chamber of a spinning end-burning rocket. Cold flow experiments employing a porous plate to represent the propellant surface were conducted. The experiments were designed to simulate dynamically the conditions in a typical cylindrical rocket combustion chamber. Pressure measurements at the plate and in the flow were correlated with smoke traces to arrive at a physical description of the flowfield in which solid-body rotation gives way to a high-speed vortex in the chamber at sufficiently high motor spin rates. The experimental correlation of the onset of this flow transition with a critical value of the Rosby number is in agreement with a theoretical analysis, and it is concluded that the vortex development is a characteristic of the inviscid rotating flow. The experiments also indicate that significant interaction between the vortex and the propellant surface is little affected by chamber length or nozzle entrance shape.

Experimental investigation of boron combustion in air=augmented rockets

Abstract: Studies have been made using a windowed combustion tunnel to examine the mixing and burning between subsonic air and a supersonic fuel-rich exhaust of a rocket motor burning hydrogen-oxygen-boron mixtures. The reaction processes were recorded by high-speed cinephotography. Results of experiments are presented in which the following parameters were varied: 1) boron concentration in the propellant (up to 55% by weight), 2) nonequilibrium chamber temperature of the primary rocket (750 °K to 2500 °K), and 3) air to propellant flow ratio (3 to 15). The temperature of the primary rocket was calculated by assuming boron as a heat sink. These calculations showed good agreement with experimental data at low chamber temperatures. The strong influence of the primary nonequilibrium chamber temperature on the boron combustion efficiency was demonstrated using the results of particle sampling probes and c*-efficiency measurements. By increasing the chamber temperature from 750°K to 2000°K the over-all reaction efficiency was improved from 85 to 94%.

Hydraulic cylinder with pressure control

Abstract: A pressure-actuated control valve which is responsive to an increase in pressure in the contracting or discharge chamber of a hydraulic actuator to restrict discharge flow from said chamber thereby reducing the velocity of the movable barrier therein. The operation of the valve is conditional on inlet pressure as it is held in a nonrestricting position by pressure fluid being admitted to the intake or expanding chamber and moves to a flowrestricting position only when a predetermined loss of pressure occurs in the intake chamber. An additional valve may be included in the system which places the actuator discharge and intake supply passages in communication to shunt fluid therebetween when discharge chamber pressure increases to a predetermined value.

Automatic control for balanced pressure process

Abstract: A PROCESS AND APPARATUS FOR STERILIZING ARTICLES SEALED IN PACKAGES MADE OF SEMI-PERMEABLE MEMBRANES, AND WITH OR WITHOUT POROUS OVERWRAP, IN A SEALED CHAMBER IN AN ATMOSPHERE OF PERMEABLE GAS. A CONTROL IS PROVIDED FOR REGULATING THE PRESSURE IN THE CHAMBER TO LIMIT THE DIFFERENTIAL PRESSURE BETWEEN THE PRESSURE INSIDE THE PACKAGE AND THE PRESSURE IN THE CHAMBER TO A PREDETERMINED VALUE SO THAT THE PRESSURE INSIDE THE PACKAGE WILL NEVER BE SUCH AS TO RUPTURE THE PACKAGE AND THE CHAMBER PRESSURE WILL NOT EXERT A PRESSURE ON THE OUTSIDE OF HE PACKAGE WHICH MIGHT DAMAGE ITS CONTENTS. THE STERILIZING GAS IS AN EPOXIDE, PREFERABLY ETHYLENE OXIDE.

Theoretical study of propellant behavior during thrust chamber depressurization

Abstract: A mathematical model that permits computation of burning rates of solid-propellant rocket motors during pressure transients is presented. The conservation equations in the solid and the gas phases are coupled with the chamber over-all mass balance equation. The method is used to compute the burning rate behavior during rapid depressurizations. The results of the computations are used to obtain dP/dt—extinguishment limits of solid propellants in terms of appropriate parameters. The agreement with the experimental quenching limit data is good.

Constant Chamber Pressure Throttling of an Expansion-Deflection Nozzle

Abstract: Thrust throttling at constant chamber pressure is desirable for certain advanced engine applications. An expansion-deflection (E-D) nozzle is by its very nature altitude-compensating and throttleable. Additionally, the chamber pressure, Pc, can be maintained constant with pintle axial displacement. A study was conducted to examine the effect of throttling an E-D nozzle on nozzle performance. The analysis used the two-dimensional axisymmetric method of characteristics to calculate nozzle wall static pressure and nozzle thrust. The experimental program consisted of cold flow testing and engine testing. Using the cold-flow data (measured net thrust and chamber pressure), nozzle thrust coefficients were calculated. The effect of throttling on throat discharge coefficient and the effect of open and closed wakes on plug base pressure were studied. Test variables included throat area, nozzle pressure ratios, and throat flow angle. Analytical and experimental agreement was good. Calculated static pressure variations along the nozzle contour were in good agreement with those experimentally measured.

Simple Flow Proportional Detector for Soft X Rays

Abstract: A simple small (5 cm long) flow proportional detector for soft x rays is described. The detector is constructed from 3.175 cm hexagonal aluminum bar stock. The detector window is cut in one face of the bar and the ultrathin window seals on that face. O‐ring construction is used to allow easy replacement of the 0.00254 cm tungsten wire. The operation of the detector at subatmospheric pressure in a high vacuum chamber is described. Vacuum and gas connections to the detector and to a manometer are shown which allow operation at 100–150 Torr with reference to the chamber pressure. Operating voltage using P‐10 gas and counting monochromatic Al Kα at 8.34 A is 950 V at 150 Torr and 1750 V at 760 Torr.

Investigation of Combustion Overpressure During Ignition of the Apollo Block II SPS Engine (AJ10-137) (Phase 4, Part 2)

Abstract: : An investigation was conducted to determine the magnitude and duration of combustion overpressure during ignition of the Apollo SPS Block II engine. Fifty-four engine starts were made at a pressure altitude of 115,000 ft for a total of 62 sec of firing time. Engine hardware and propellant temperatures were varied from 30 to 70F but did not influence combustion overpressure. The magnitude of combustion overpressure was affected by propellant injector fill characteristics which were a function of bipropellant valve opening time and target chamber pressure. The overpressure ranged from 0 to 48 percent above the steady-state chamber pressure level for durations ranging from 15 to 39 msec. The overpressure duration was not influenced by the various starting conditions.

Helmholtz Oscillations in Pulsating‐Combustion Chambers

Abstract: An investigation has been made of the conditions under which liquid‐fueled pulsating‐combustion chambers operate as Helmholtz resonators. The experimental apparatus consists of a vertical, cylindrical combustion chamber that is partially filled with a liquid fuel and completely closed except for a single, sharp‐edge orifice in the top end. A manifold chamber and an exhaust pipe are mounted above the orifice. The pulsating‐combustion process operates on air drawn intermittently from a steady flow of air that is supplied through the manifold. Measurements have been made of chamber pressure as a function of time for various chamber configurations and exhaust‐pipe lengths. Results show that the mode of operation is either anharmonic or harmonic, depending on whether the exhaust‐pipe length is smaller or larger, respectively, than a critical transition length. The transition to harmonic operation is accompanied by a sudden jump in both frequency and pressure amplitude. Theoretical double‐cavity resonator frequencies agree well with experimental frequencies for the harmonic mode of operation but are larger than frequencies for anharmonic operation by factors of about two or greater. The harmonic mode of operation appears to be governed by a Helmholtz‐type mechanism, whereas the anharmonic mode is governed predominantly by heat‐transfer processes.

Improvements in or relating to Fluid-Supply Systems Utilising a Bleed from an Engine or Compressor

Abstract: 1,157,962. Ventilating aircraft. PLESSEY CO. Ltd. 28 Sept., 1966 [8 Oct., 1965], No. 42738/65. Heading F4V. [Also in Division F1] The invention relates to an air supply system in which air is tapped for example from two different points of a compressor of a gas turbine engine for use for aircraft cabin pressurization. The air tapped from one point of the compressor is at a pressure greater than the required air pressure and that tapped from the other point is at a pressure less than the required air pressure. The air at the higher pressure is passed to an air turbine while that at the lower pressure is supplied to an air compressor driven by the air turbine, the air discharging from the turbine and that discharging from the compressor being mixed and thence supplied to the point of use. In the embodiment shown a chamber 5 is provided and an assembly comprising a rotor 1 and shaft 2 is rotatably mounted therein. The rotor 1 comprises a centrifugal air compressor 3 and an air turbine 10. High pressure air tapped from the engine compressor is supplied through line 7 and passes by way of a control unit 8 through lines 13 to nozzles 9 which direct it on to the air turbine. Lower pressure air tapped from the engine compressor passes through duct 4 to the air compressor 3, the air delivered by the compressor and that discharged from the turbine mixing in the chamber 5 and then passing through line 6 to the point of use. The control system for the turbine comprises a piston 11 disposed in a cylinder 12 the axial position of the piston determining the number of lines 13 and hence turbine inlet nozzles 9 through which high pressure air may flow. The piston 11 is connected to a piston 14 disposed in a cylinder 15, the piston 14 being subject at its right-hand side to pressure of the high pressure air in line 7 so that the pistons 11 and 14 are pressure balanced. The rod connecting the pistons 11 and 14 is connected to a control piston 16 disposed within a cylinder 17, one side of the piston being subject to ambient pressure and the other side being subject to pressure within the chamber 5. The excess of chamber pressure over atmospheric pressure thus tends to move the piston 11 to the left against the loading of spring 18, so as to cut off the number of turbine nozzles 9, so that less air is tapped through the line 7 and the power of the turbine 10 is reduced. Thus the pressure within the chamber 5 and so the air supplied to the cabin is reduced.

Injector/Chamber Scaling Evaluation-TRW Injector Development

Abstract: : This report describes the results of TRW injector development tests. This project, a task under the overall Minimum Cost Design Space Launch Vehicle (MCD/SLV) Program, has as a goal the development of low-cost injectors capable of performing at 90% theoretical Isp (shifting), 250,000-lb thrust using N2O4/UDMH propellants, and will evaluate their scalability up to the multimillion-lb- thrust class. A total of seven injector and three chamber configurations were tested. Maximum performance obtained was approximately 88% of test site theoretical shifting Isp (90% vacuum Isp). Dynamic combustion characteristics of this concept were evaluated by artificially inducing chamber pressure overpressures of 100% or greater. In all tests, chamber pressure recovered to within 10% of the original value within 30 to 40 milliseconds, and the engine is considered dynamically stable.

Strain gage instrumentation for a light gas gun

Abstract: : Variable-resistance strain gages were used to study the operating characteristics of a light-gas gun. Gages were cemented on the outer surface of the gun at several locations, in order to determine chamber pressure, piston velocity, and pressures in the central breech. The high-pressure transition section deformed plastically in most rounds, and a method is suggested for estimating maximum pressures from strain-time records. Results are given for various helium pressures and powder charges.

Ratioed pneumatic repeater

Abstract: A diaphragm ration capsule separates a recess within a housing into a signal pressure chamber and a repeating pressure chamber; for the condition of signal pressure lower than repeating pressure, the diaphragm ratio capsule is moved away from an exhaust valve permitting pressure in the repeating chamber to vent to atmosphere; for the condition of signal pressure higher than repeating pressure the diaphragm ratio capsule forces the exhaust valve to move which in turn unseats a supply valve permitting the supply pressure to enter the repeating pressure chamber; thus the repeating chamber pressure follows the pressure of the signal chamber; the capsule has two different sized diaphragms for ratio function, bias pressure may be applied between the diaphragms.

Design Characteristics and Performance of a Combustor for Use as an Ionized Gas Source in Magnetohydrodynamic Power Generation Studies

Abstract: : Design characteristics and performance of a combustor for use as a high energy, ionized gas source in magnetohydrodynamic power generator studies are described. The liquid oxygen (LO2)/JP-4 combustor was operated over a chamber pressure range from 240 to 300 psia and at a characteristic exhaust velocity efficiency of 91 plus or minus 1 percent for oxidizer/fuel ratios ranging from 2.0 to 3.1. Combustor power output was approximately 17.5 to 20.5 megawatts (MW) over its range of operation. Provisions were incorporated into the design for injection of a saturated solution of water and cesium carbonate seeding agent into the thrust chamber to provide a high ion concentration in the exhaust gases.

Pressure Measurements and Gas-Flow Analysis in Chambers A and B during Thermal-Vacuum Tests of Spacecraft 2TV-1 and LTA-8

Abstract: Pressure measurements and gas flow analysis during thermal vacuum tests of manned spacecraft indicating adequate space vacuum simulation

High-thrust throttleable monopropellant engine system

Abstract: Recent Mars soft-landing studies show that a propulsion system is required to accomplish the terminal landing sequence. Relatively high thrust levels and throttling ratios are required and engine weight is extremely significant since it comprises nearly one-third of the propulsion system weight due to the relatively small total impulse which is required. To overcome potential problems with scaling conventional catalytic thrusters, a pilot-chamberinitiated, thermal decomposition reactor concept has been studied. The pilot chamber operates catalytically on 5% to 15% of the total flow. The remainder reacts thermally in the main chamber which is void of catalyst. The characteristics of such a chamber have been experimentally studied and it shows high potential for further development. Operation at design values of L* = 150 in and G = 0.1 lbm/in.-sec appears completely feasible if a suitable heat sink "flame holder" is utilized.