Showing papers on "Chamber pressure published in 1983"

Gas pressure measuring and regulating device and method

Abstract: A pressure measuring and regulating device and method for measuring and controlling the pressure within an enclosure such as a pressurized cuff of a medical apparatus, e.g. an endotracheal tube, a tracheostomy tube, or the like, includes effecting communication between a chamber in one end of a hollow barrel. Within the bottom of the chamber is disposed a reservoir containing an indicating fluid, such as mercury. The reservoir communicates with an indicating channel which is visible from the exterior of the barrel. The chamber and the reservoir are exposed to the pressures within the enclosure such that the indicating fluid is displaced into the indicating channel to provide an indication of the pressure within the enclosure. An exteriorly operated regulating member is provided for effecting precise adjustment of the chamber pressure and thus the enclosure pressure and which pressure is simultaneously registered in relation to a monitoring scale associated with the indicating channel.

Double glass sheet insulating windows

Abstract: A window structure includes a pair of panes of glass maintained in spaced apart relationship by a separating unit to define an interior chamber between the panes substantially impervious to the ambient atmosphere. The separating unit includes a pressure equalization device for controlling the volume of the chamber to maintain the interior chamber pressure substantially equal to the ambient atmospheric pressure. The separating unit can also include a desiccant-filled container in fluid communication with the chamber for dehydrating air within the chamber.

Incomplete Combustion: A Possible Cause of Combustion Instability

Abstract: The performance of and the combustion in solid-propellant rocket motors may be affected by characteristic length (L*). For small characteristic lengths, the chamber pressure and characteristic velocity may be lower than in similar motors with larger L*. Oscillatory combustion may take place if the L* is small enough. In the past, L* oscillations have been explained by an oscillatory heat feedback mechanism and subsequent oscillatory propellant pyrolysis. The same phenomena—i.e., lower chamber pressure, lower characteristic velocity, and oscillatory combustion—can also occur in Hquid-propellant, hybrid, and airbreathing rocket motors. It is shown that these phenomena may be explained by assuming a finite reaction rate in the gas phase in combination with small residence times. Even if a constant burning rate or propellant mass flow rate is assumed, the coupling between the energy release in the gas phase and the residence time is sufficient to cause oscillatory combustion. A stability boundary criterion for solid-propellant rocket motors is derived and is found to be in agreement with experimental results.

Plasma etching of niobium with CF4/O2 gases

Abstract: Niobium may be used as an electrode and wiring material in Josephson junction technology. For edge coverage of lines patterned in these films, it is critical to produce a controlled, tapered edge profile. Reactive etching is one of the feasible techniques to accomplish this goal. Plasma etching of niobium in a CF4/O2 gas plasma was studied using an anodically coupled parallel plate reactor. The edge angle was found to be dependent mainly on the etching rate ratio (ERR) of the photoresist to the underlying Nb. Factors which affect the etch rates of Nb and photoresist (thus ERR) such as Nb surface area, temperature of the substrate table, and oxygen concentration in CF4 will be discussed. Parametric studies on the effects of total gas flow rate and chamber pressure will also be reported.

Generalized response of chemiluminescence analyzers

Abstract: The mass flow and chemical kinetic equations for a gaseous chemiluminescence (CL) analyzer are formulated and solved. The resultant equation can be used to predict the absolute response of the analyzer as a function of the sample flow rate, the sample gas pressure, the chamber pressure, the chamber volume, the mass flow rate and mole fraction of the reagent gas, and the rate constants of the relevant chemical processes. Thus, the equation allows optimization of these parameters. It is shown that for varying sample pressure the analyzer can be used to measure either concentration or mole fraction and that interfering reactions can sometimes be discriminated against by chamber pressure variation. The equations apply equally well to a flowing‐liquid‐phase CL analyzer, if the chemical mechanism considered is appropriate.

Operating method of filter module

Abstract: PURPOSE:To operate each module at about the same filtration rate by keeping the filtration side of each module of the filter modules, wherein several modules are connected in series, at a specified pressure. CONSTITUTION:N numbers of modules A1, A2,...An having the same performance (desalting efficiency, permeability etc.) are connected in series. The filtrate pressure (filter chamber pressure) of each module is equalized to the pressure difference Pk-n between the original liquid inlet pressure Pk of the module Ak and the original liquid inlet pressure Pn of the module An at the lowermost stream by controlling the pressure regulating valve Vk (k=1, 2,...n-1, and n is excluded) in the filter chamber of each module Ak. The modules are operated under such control. This control is usually performed automatically by using a constant pressure valve.

D-Cracking in Portland Cement Concrete Pavements

Abstract: A study was conducted to determine the mechanisms involved in the Iowa Pore Index Test and investigate ways to modify and supplement the testing procedure to increase its accuracy and sensitivity. In the study a modified IPIT was developed which utilizes chamber pressures up to 1379 kPa (200 psi). Instead of using the volume of water entering the aggregate pores over a specified time period the degree of saturation which occurred in the aggregates at various chamber pressures was used. Relationships between degree of saturation and chamber pressure were developed and found to provide a general index of the aggregate freeze-thaw durability properties.

Gas-powered flashlight

Abstract: A hand-held lighting device powered by a combustible gas stored in a self-contained fuel chamber and utilizing an incandescent mantle for illumination, the lighting device being provided with a two stage fuel regulator for supplying vaporized fuel over a wide temperature range and in any orientation, an aspirated pilot assembly fixedly mounted within the lighting device adjacent the mantle and ignitable by an ignition assembly actuable from outside the housing, and a shock absorbing mantle mounting. The regulator includes a first stage for receiving a first flow of gas at a fuel chamber pressure and for producing therefrom a second flow of gas at a predetermined pressure difference lower than the first gas flow, and a second stage for receiving the second gas flow and producing therefrom a third gas flow at or below a predetermined pressure. The shock absorbing mantle mounting generally includes a two-piece cantilevered member, the two pieces being slidingly and coaxially mated and biased with respect to one another.

Pulsating brake accelerator for rail vehicle air brake

Abstract: A pulsating brake accelerating device for an indirectly operating air brake for rail vehicles has a pulsator (12), which is attached to the brake pipe (BP) via a jet (23). The pulsator (12) forms a mixed pressure from two pressures. One of the pressures is formed by the pressure of the brake pipe (BP) via a jet (23) and the other pressure is formed by pressure from a control chamber (QAC) via another jet. At every braking level the pulsator (12) drains mixed pressure pulses off into the atmosphere, while at the same time the brake pipe pressure and the control chamber pressure is lowered via the mixed pressure pulsator (12). The mixed pressure can consist of two valves (14, 15). The control element (4) of the brake accelerator unit can be the emergency brake piston, which monitors several valves, one of which is the pulsator-excitation valve (8).

Distributor injection pump for a vehicle diesel internal combustion engine

Abstract: In a distributor injection pump in which the internal chamber, supplied with fuel by a pre-delivery pump, is connected to a chamber of a diaphragm cell, the diaphragm of which is connected to a control slide valve adjusting the delivery quantity, so that the admissible smoke emission can thereby be limited in full load operation of the internal combustion engine, the other chamber of the diaphragm cell is connected to the feedline to the pre-delivery pump In this way a variation of the feed pressure caused by a change in the position of the motor vehicle and thereby any variation of the internal chamber pressure are cancelled out so that the set admissible smoke emission is not adversely affected

Weapon Chamber Pressure Measurement

Abstract: : Measurements of pressure inside large caliber weapons are critical for establishing the balance between crew safety and combat effectiveness. A 2% error in chamber pressure measurement can result in a 3% change in weight, a 4% change in effective range, and a 6% change in fatigue life. A study of electrical pressure transducers used to measure large caliber weapon chamber pressure was conducted at Aberdeen Proving Ground from January 1979 to March 1982. Extensive testing, at pressure levels from 34 to 785 MPa (5,000 to 110,000 PSI) was done to evaluate 15 different types of pressure transducers. Tests to evaluate bias between readings from different types of transducers as well as the variability of readings produced by a single type of transducer were conducted. In the laboratory, both dynamic and static pressure readings were made. In the field, a 175mm gun was used to evaluate differences in transducer performance.

A New Functional Relationship between Buring Rate and Initial grain Temperature in Composite Solid Propellants

Abstract: By depicting the transfer of heat and combustion reaction to take place within thin gas layers close to the propellant burning in a steady-state fashion, a new theoretical relationship has been deduced to describe the burning rates of solid propellants as a function of initial grain temperature and chamber pressure. The proposed equation is where BR=burning rate, , k, n = constants, energy, Ti=initial grain temperature, C = effective temperature rise, P = Combustion chamber pressure and Z = mean Compressibility factor. The proposed model was tested and evaluated visa vis strand burner data and it was found that the deviation of the computed burning rates from the measured ones ranged zero to 2%. This leads to the conclusion that the model proposed herein, both physical and mathematical, correctly represents the reality of combustion process of solid propellants, thus proving to be useful in design an performance analysis of propulsion system.

Advanced LOX/H2 engine technologies for future OTVs

Abstract: The optimization methods and trade studies which were used to define a 1980 state-of-the-art design of orbital transfer vehicles are summarized. The advanced thrust chamber, turbomachinery, and engine power cycle technologies recommended for development and verification during the 1980's are discussed. The state-of-the-art design serves as one of the reference points for evaluation of the advanced technology concepts. A second reference point is provided by the 1960 state-of-the-art RL-10 engine. Advanced heat energy extraction concepts in the combustor and injector are presented that will permit the high chamber pressures expected of the advanced expander cycle engine concept. Advanced turbomachinery concepts are selected that will help utilize efficiently the heat energy extracted in the thrust chamber and aid in uprating chamber pressures to values five times those realized with 1960 to 1980 technologies. The higher chamber pressure benefits are maximized with nozzle concepts that will package within a short retracted length and extend to the very high expansion area ratios required for specific impulse values significantly higher than those now realized by operational systems. Control system component concepts studied will allow utilization of the high turbine drive energy levels in a reliable repeatable manner that will reduce program risk and enhance overall space transportation system mission life cycle cost.

The use of airgun pressure pulses for calibrating a low‐frequency standard hydrophone*

Abstract: A new technique is developed for calibrating a low-frequency hydrophone. The technique involves the use of pressure pulses radiated by the Par 0.65 liter airgun when fired at a fixed depth but with various values of initial chamber pressure. The sensitivity of a low-frequency hydrophone, when determined by the proposed technique, is found to be in agreement with that obtained by using the so-called “impulse method”.

Fluid pressure signal transducer

Abstract: A transducer for providing a modulated fluid pressure control signal having an electromagnetic stator operable in response to an electrical control signal to apply a magnetomotive torque to a rotary valve member for controlling fluid flow to and from a control signal chamber. A diaphragm senses the difference between the control signal chamber pressure and atmospheric pressure and is operable in response thereto for moving the rotor axially for varying the pole overlap and magnetomotive torque on the rotor.