Velocity supersonic

Why are fhese beams, or jefs, distinguished from effusive beams by fheir description as supersonic In some ways fhis description is rafher misleading, firsf because particles in an effusive beam may well be fravelling af supersonic velocities and, second, because fhe name implies fhaf somefhing special happens when fhe particle velocities become supersonic whereas fhis is nof fhe case. Whaf supersonic is meanf fo imply is fhaf fhe particles may have very high Mach numbers (of fhe order of f 00). The Mach number M is defined as... 

DETONATION Explosion in which the flamefront advances at more than supersonic velocity. 

Flame Plating—the deposition of a hard metal coating onto a substrate via application of molten metal at supersonic velocities. 

Shock waves travel at supersonic velocities and exhibit a near discontinuity in pressure, density, and tempera-... 

Unlike the orifice or nozzle, the pipeline maintains the area of flow constant and equal to its cross-sectional area. There is no possibility therefore of the gas expanding laterally. Supersonic flow conditions can be reached in pipeline installations in a manner similar to that encountered in flow through a nozzle, but not within the pipe itself unless the gas enters the pipe at a supersonic velocity. If a pipe connects two reservoirs and the upstream reservoir is maintained at constant pressure P, the following pattern will occur as the pressure P2 in the downstream reservoir is reduced. 

For flow in a pipe of constant cross-sectional area, therefore, a shock wave can develop only if the gas enters at supersonic velocity. It cannot occur spontaneously. 

Basic Breakup Modes. Starting from Lenard s investigation of large free-falling drops in still air,12671 drop/droplet breakup has been a subject of extensive theoretical and experimental studies[268] 12851 for a century. Various experimental methods have been developed and used to study droplet breakup, including free fall in towers and stairwells, suspension in vertical wind tunnels keeping droplets stationary, and in shock tubes with supersonic velocities, etc. These theoretical and experimental studies revealed that droplet breakup under the action of aerodynamic forces may occur in various modes, depending on the flow pattern around the droplet, and the physical properties of the gas and liquid involved, i.e., density, viscosity, and interfacial tension. 

In some spray forming processes, the atomization gas exits the atomizer nozzle(s) at sonic or supersonic velocities. The gas may expand... 

A new production technique fully cost competitive with current processes could be the reduction of magnesium oxide by carbon to produce magnesium metal as a vapour and carbon monoxide gas this technique, according to Brooks et al. (2006), will involve rapid quenching of the Mg vapour through a nozzle at supersonic velocity to avoid Mg reversion to magnesium oxide. 

An explosion can be defined as a fast, transient, exothermic reaction. It needs exothermicity to generate energy and must be fast to generate this energy very quickly in a transient pulse. We can also distinguish between events in which the reaction propagates at subsonic velocity as an explosion and one in which the reaction propagates with sonic or supersonic velocity as a detonation. 

The hot-wire anemometer can, with suitable cahbration, accurately measure velocities from about 0.15 m/s (0.5 fl/s) to supersonic velocities and detect velocity fluctuations with frequencies up to 200,000 Hz. Eairly rugged, inexpensive units can be built for the measurement of mean velocities in the range of 0.15 to 30 m/s (about 0.5 to 100 ft/s). More elaborate, compensated units are commercially available for use in unsteady flow and turbulence measurements. In cahbrating a hotwire anemometer, it is preferable to use the same gas, temperature, and pressure as will be encountered in the intended apphcation. In this case the quantity I RJAt can be plotted against /v, where I = hot-wire current, = hot-wire resistance. At = difference between the wire temperature and the gas bulk temperature, and V = mean local velocity. A procedure is given by Wasan and Raid [Am. Inst. Chem. Eng. J., 17, 729-731 (1971)] for use when it is impractical to calibrate with the same gas composition or conditions of temperature and pressure. Andrews, Rradley, and Hundy [Int. J. Heat Mass Transfer, 15, 1765-1786 (1972)] give a cahbration correlation for measurement... 

Up to this time, the pressure thruout the region from the piston to the advancing front remains constant. Even after the piston is stopped the front continues to advance at its previous supersonic velocity and the pressure remains at this constant value for a considerable distance behind the front. However, the movement away of the material immediately ahead of the piston creates a rarefaction, for there is nothing to take the place of removed air. The pressure within this rarefaction zone will fall below the original pressure and will even approach.a vacuum in some cases. While the shock front continues to advance, the rarefaction wave follows some distance behind. It has been shown that in an inert medium, such. a rarefaction wave will always advance faster than the original shock front and is bound to overtake... 

Arrow Projectile (Pfeilstabiles Geschoss, in Ger), also called Needle Shell (Ref 5), is a slender, very long, fin-stabilized, projectile, fired from a smooth-bore gun at supersonic velocity. Its development, described in Refs 1 4, may be considered as one of the outstanding Ger achievements of WWII. Some info on these projectiles is given in Ref 3, pp 9 10... 

The so-called "secondary or after flame which arises from the combination of reaction products of primary flame (such as of CO) with surrounding oxygpn in the air, is also dangerous. Other causes of ignition include any naked flame present in mine hot or inflamed particles ejected from the expl adiabatic compression of the gas by a shock wave at supersonic velocity general adiabatic compression of a body or pocket of gas electric sparks or sparks produced by drills hitting stones (which are sometimes embedded in coal) (Refs 7b, 7c, 16a, 22 31)... 

Direct experimental proof of the possibility of rapid gas ignition under compression by a shock wave was given by Leipunskii and the author. Compression by the shock wave was accomplished by shooting a fast bullet from a special small-caliber rifle into the explosive mixture. In front of the body, which was flying with supersonic velocity, a steady shock wave formed whose velocity with respect to the gas was equal to the velocity of the body. This condition determined the pressure and temperature amplitudes in the wave. The duration of the compressed state of the gas did not exceed 10"5 sec. For a bullet velocity of 1700-2000 m/sec, ignition of the mixture 2H2 + 02 + 5Ar was observed. 

There is some confusion about what is meant by Shock Sensitivity. In this article we will define shock sensitivity as the reaction of condensed expls in time frames of microseconds to shocks whose amplitude is generally in the kilobar range. Furthermore, shocks are defined as steep-fronted compression waves that propagate at supersonic velocities in the medium that they traverse. Thus the article will be limited primarily to consideration of the effects of explosively generated shocks... 

If Pi is increased, the acoustic velocity may be shown to remain unaltered, but, since the density of the gas is increased, the rate of disharge is greater. The orifice and the venturi tube are alike insofar as discharge capacity is concerned. The only difference is that with the venturi tube, or a converging/diverging nozzle, a supersonic velocity may be attained at discharge from the device, while with the orifice the acoustic velocity is the maximum value possible at any point. 

In the case of the finite projectile, the shock wave leaves the tip at an angle with the main flow which exceeds the Mach angle, on account of the conical nose which follows the tip. Appropriate corrections may be applied, however, and the shock-wave angle from such a sharp-nosed object remains an accurate means of measuring supersonic velocities. 

Operation. In a diffusion pump, the pump fluid is heated so that a vapour pressure of 1-10 mbar is established in the boiler. The vapour rises in the jet assembly where it is expanded through nozzles and enters the space between the nozzle and the cooled wall of the pump at high supersonic velocity. Pumping action is based on the transfer of momentum in collisions between the high speed (several times the speed of sound) pump fluid vapour molecules and particles that have entered the vapour jet. 

Cavitation occurs when bubbles containing either vapor or gas are formed by reduction in the local pressure at constant temperature (Brennan, 1995 Knapp et al., 1979 Young, 1989) such as the rapid movement of the fluid past an impeller blade, through a pump, or in this case through a restriction (orifice) at near supersonic velocities. Quantifying the cavitation number is debatable, but it can be derived from the Bernoulli equation. Lush (Young, 1989) uses a throat cavitation number (aT) defined as... 

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