Showing papers on "Overpressure published in 1979"

Sonic-boom minimization with nose-bluntness relaxation

Abstract: A procedure which provides sonic-boom-minimizing equivalent area distributions for supersonic cruise conditions is described. This work extends previous analyses to permit relaxation of the extreme bluntness required by conventional low-boom shapes and includes propagation in a real atmosphere. The procedure provides area distributions which minimize either shock strength or overpressure.

Wind-tunnel investigation of the validity of a sonic-boom-minimization concept

Abstract: The Langley unitary plan unitary plan wind tunnel was used to determine the validity of a sonic-boom-minimization theory. Five models - two reference and three low-boom constrained - were tested at design Mach numbers of 1.5 and 2.7. Results show that the pressure signatures generated by the low-boom models had significantly lower overpressure levels than those produced by the reference models and that small changes in the Mach number and/or the lift caused relatively small changes in the signature shape and overpressure level. Boundary-layer effects were found in the signature shape and overpressure level. Boundary-layer effects were found to be sizable on the low-boom models, and when viscous corrections were included in the analysis, improved agreement between the predicted and the measured signatures was noted. Since this agreement was better at Mach 1.5 than at Mach 2.7, it was concluded that the minimization method was definitely valid at Mach 1.5 and was probably valid at Mach 2.7, with further work needed to resolve the uncertainty.

The Blast Wave from Deflagrative Explosions, an Acoustic Approach

Abstract: : Simple acoustic source theory has been applied to determine the maximum overpressure obtainable by the deflagration of nonspherical clouds. In three dimensions overpressure is generated not by the rate of energy addition but by the first time derivative of the rate. Because of this, deflagrative combustion of edge-ignited clouds produces markedly less overpressure than central, spherical ignition. Examples are presented for three nonspherical cloud and igniter geometries. The implication is that even high velocity, subsonic combustion waves cannot produce damaging blast waves and that some type of supersonic combustion or massive flame acceleration is required if a damaging blast wave is to be produced.

Process and apparatus for the controlled pneumatic filling of a reactor, dependent upon the evacuated quantity

Abstract: In a reactor in whose pressure vessel an overpressure prevails which is adjustable via a pressure allocator, it is striven to feed each feeding point with conveyed material in the desired metered amount. In order to control the entire course of the process and to avoid disturbances, the conveyed material is evacuated at a plurality of outlets (2a, 2b, 2c) in a plurality of conveying pipes (4a, 4b, 4c) connected there, variables characterising the conveying stream being measured in each conveying pipe and these measured values, if necessary after appropriate processing, being used for controlling or adjusting the overpressure and the pressure difference between the overpressure and the pressure prevailing in the conveying pipes (4a, 4b, 4c). In order to measure the pressure, the transport speed, the density and the temperature of the conveyed material, measuring sensors (5a, 5b, 5c) are used which are connected to corresponding apparatuses (3a, 3b, 3c, 6a, 6b, 6c 7a, 7b, 7c, 8a, 8b, 8c, 9, 10a, 10b, 11, 15, 16a, 16b, 16c, 17) for adjusting and stabilising the pressure, the conveyed material quantity and the conveyed gas quantity.

Method for controlling a hydraulically operated mine roof support and an arrangement for carrying out the method

Abstract: A method of operating a hydraulically expandable and collapsable prop of a mine roof support in which the cylinder space of the prop below the piston therein normally communicates with an overpressure valve adjusted to a pressure equal to the setting pressure of the prop, wherein the method comprises the steps of interrupting communication of the overpressure valve with the cylinder space of the prop while the latter is expanded and restoring the communication when the prop is pressed against the mine roof while the cylinder space is disconnected from the hydraulic pressure circuit and an arrangement for carrying out the method.

Compact-electron-beam or light-ion-beam fusion reactor cavity design using non-spherical blast waves

Abstract: The application of inhomogeneous cavity gas densities and the non-spherical blast wave resulting from an explosion in this gas offers the potential to reduce the distance between the final diode and the target in a relativistic-electron-beam (REB) or light-ion beam (LIB) fusion reactor. It can also sharply reduce the overpressure experienced by the diode after the target explosion.

Differential pressure detector

Abstract: PURPOSE:To achieve the prevention of overpressure and the reduction in temperature static pressure errors by separating medium to the partition wall side and the element side with one of elastic bodies when pressure above a detection range is applied thereby preventing the movement of the medium and absorbing the fine movement of the medium on the element side with the other elastic body. CONSTITUTION:Pressures Pa, Pb are applied in holes 39a, 39b, then diaphragms (partition walls) 36a, 36b displace and pressure media 38a, 38b move. When the pressure Pa exceeds the elastic limit of a pressure sensitive element 35, the pressure is received on the outside face of a bellows 65a and the inside face of 65b by way of the partition wall 36a, medium 38a, whereby the medium 38a is moved leftward and is sealed among the partition wall 36a and O-ring 56a, the outside face of the bellows 65a, the inside face of 65b and the element 35. Even when the O-ring is crushed as the movement of the medium stops and overpressure is applied, the bellows 65b becomes a pressure displacement body for protection of the element after preventing overpressure, thus minimizing the pressure change to be exerted upon the element 35. At this time, the thermal expansion and shrinkage of the medium 38a having been sealed may be prevented by the bellows 65a, 65b even if temperature changes.

Attenuation effects of thermal radiation on internal blast overpressure.

Abstract: : The determination of overpressure yield from internal blast has been the subject of prior investigations. Models have been developed to predict explosion thermodynamic parameters, based on equations of state, mass and energy conservation, and rate laws, utilizing high speed digital computers. Typically, thermodynamic equilibrium was assumed, an equilibrium temperature was determined, ideal gas law behavior was ascribed to product gases, and a pressure was computed. Reports of the results of these studies have typically contained a disclaimer that radiation effects have been ignored. In this investigation, a blackbody radiator model was developed and, utilizing the parameters reported in the literature for a number of explosives of common interest, a determination was made of the effect of thermal radiation as an attenuation mechanism on explosive energy and the existence of thermodynamic equilibrium. Energy losses of less than .5% were calculated and thermodynamic equilibrium was demonstrated through statistical considerations. (Author)

X-ray and pressure conditions on the first wall of a particle beam inertial confinement reactor

Abstract: Because of the presence of a chamber gas in a particle beam reactor cavity, nonneutron target debris created from thermonuclear burn will be modified or stopped before it reaches the first reactor wall. The resulting modified spectra and pulse lengths of the debris need to be calculated to determine first wall effects. Further, the cavity overpressure created by the momentum and energy exchange between the debris and gas must also be calculated to determine its effect. The purpose of this paper is to present results of the debris-background gas problem obtained with a one fluid, two temperature plasma hydrodynamic computer code model which includes multifrequency radiation transport. Spherical symmetry, ideal gas equation of state, and LTE for each radiation frequency group were assumed. The transport of debris ions was not included and all the debris energy was assumed to be in radiation. The calculated x-ray spectra and pulse lengths and the background overpressure are presented.

Some effects of applying sonic boom minimization to supersonic cruise aircraft design

Abstract: This paper presents a discussion of an aircraft shaping method to control sonic boom over-pressure levels along with the analysis of wind-tunnel data which validated the method. The results indicate that the sonic boom minimization method can guide the design team choices of aircraft planform and component arrangement toward a low-boom-level configuration while permitting sufficient freedom and flexibility to satisfy other design criteria. Further, it is shown that off-design flight conditions do not drastically change the overpressure sonic boom shape and strength.