US3759134A

US3759134A - Supersonic flow deflector and silencer

Info

Publication number: US3759134A
Application number: US00211996A
Authority: US
Inventors: L Cox; C Spyropoulos
Original assignee: United States Department of the Army
Current assignee: United States Department of the Army
Priority date: 1971-12-27
Filing date: 1971-12-27
Publication date: 1973-09-18
Anticipated expiration: 1990-09-18

Abstract

A super-sonic flow deflector for deflection of under-expanded gas flow at an angle as great as the exit angle of the deflector surface. A scroll container accompanies said deflector to act as a collector for the exhaust gases after deflection.

Description

limited States Patent Cox et al. [4 1 Sept. 18, 11973 1 SUPERSONIC FLOW DEFLECTOR AND 916,885 3/1909 Maxim 89/14 1) SILENCER 2,449,571 9/1948 Walker 89/14 D 956,717 5/1910 Moore 89/14 D [75] Inventors: Lyndon S. Cox, Silver Spring, Md.; Chris E. Spyropoulos, Washington, Primary Examiner-Benjamin A. Borchelt [73] Assignee: The United States of America as Assistant Examiner-Hif represented by the Secretary of the y- "y sal'agovltz et Army, Washington, D.C.

[22] Filed: Dec. 27, 1971 21 Appl. No.: 211,996 57 ABSTRACT [52] US. Cl 89/14 D A p rn fl deflector f r efl i n f under- [51] Int. Cl F4lf 17/12 e pa ed gas flow at an angle as great as the exit angle [58] Field of Search 89/ 14 D, 14 C, 14 R of the deflector surface A ll c n in r mpanies said deflector to act as a collector for the exhaust References Cited gases after deflection.

UNITED STATES PATENTS 1,021,742 3/1912 Moore 89/14 D 3 Claims, 3 Drawing Figures Pmemzusrrw 3,759,134

FIG I F IG 2 39 FIG 3 INVENTORS LYNDON S. COX, CHRIS E. SPYROPOULOS by HARRY M SARAGOVITZ EDWARD J. KELL)? HERBERT BERL,

and SAUL ELBAUM their ATTORNEYS SUPERSONIC FLOW DEFLECTOR AND SILENCER The invention herein described may be manufactured, used and licensed by or for the United States Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a unique supersonic flow deflector and silencer. The silencing function has an application to quieting of muzzle blast when used in weapons.

The immediate application of the instant invention is in the field of weaponry where several problems are encountered and caused by muzzle blasts. One of these problems is the obscuration of the line of sight by dirt or dust raised from the ground by the muzzle blast.

Another problem caused by muzzle blast is the disclosure of the position resulting from movement of foliage near the muzzle under the influence of the muzzle blast.

Still another problem is the oscillation of the barrel from muzzle jump or vertical movement of the muzzle relative to the breech of the barrel.

Other problems are damage to nearby structures from impingement of the high velocity flow of the muzzle blast and exposure of the shooter or overhang of barrel from protective structure, such as sandbags, resulting from the need for clearance to avoid the above problems.

Also, when a weapon is used in an aircraft there is a need to protect the air frame from the blast pressure.

Many solutions have been proposed and some employed to minimize the above problems. Some of those devices proposed have included a series of vanes by which the muzzle blast is deflected, while still others use ports in an enclosure to direct the muzzle blast.

Other prior devices use a simple slot cut in the end of an extension portion to roughly allow the gas to escape prior to exit of the slug or bullet.

None of these prior art devices function with a high degree of efficiency, which is one of the objects of the present invention. The instant invention provides a means of producing a controlled deflection by utilizing a compact addition on the barrel of the weapon.

Accordingly, one object of this invention is to provide an improved supersonic flow deflector.

Another object of this invention is to provide an improved muzzle blast deflector for use on weapons.

A still further object of this invention is to provide a muzzle blast deflection silencer for use in weapons. These and other objects of the invention will become apparent when reference is had to the accompanying specification and drawings in which:

FIG. 1 is a sectional diagrammatic view of the end of a conventional weapon barrel;

FIG. 2 is a sectional diagrammatic view of a weapon barrel employing the supersonic flow deflector of this invention, and

FIG. 3 is a sectional diagrammatic view ofa weapon barrel employing both the supersonic flow deflector concept and the blast deflection silencer.

Referring now to FIG. 1, there is shown a conventional rifle barrel having a bore or passage Ill and an end surface 12. It is noted that end surface 12 is generally perpendicular to the circumference of barrel I0. When the projectile is fired through passage lit, the muzzle blast takes on a shape generally designated by arrows l3, l4 and 15. As noted, the muzzle blast is supersonic flow within a shock bottle defined by an oblique shock as at 113 and w. This conventional form of muzzle blast lends itself to all the problems enumerated beforehand.

The deflector comprising the instant invention is shown in FIG. 2 and is employed on a barrel 2 11) having a passage Zil. The deflector comprises an extending portion 23 having a curved concave surface 241. It is noted that the tip of portion 23) does not interfere with the smooth passage of a projectile exiting from passage 2ll. Opposite portion 23 has a vertical end face 22 such as in conventional weapons. A projectile fired from passage M will cause a muzzle gas flow to bend and be shaped in the direction shown by

arrows

25, 26, 27 and 28. As noted, surface 243 bends one portion of muzzle gas flow downwardly as at 25 to a point near 2% where it effects the lower portion of the supersonic flow. The member 23 also referred to as a curved lip on one side of the muzzle changes the shoclt bottle shape resulting from a conventional weapon such as in lFllG. ll.

When the pressure ratio across the orifice of the passage is much greater than required for sonic flow velocity, as in the case with most weapons, a shock bottle develops as is shown in FIG. ll. Normally the introduction of a solid surface within the shock bottle and outside the projected area of the passage or nozzle does not strongly affect flow across the center line. However, when the momentum of flowing gas on one side is turned, as in FIG. 2, and made to re-enter the flow within the shock bottle, the flow of the complete shock bottle can be affected. While sub-sonic flow deflection results from viscous forces as well, supersonic flow deflection results from momentum interactions. The flow deflector can be used to deflect the shock bottle from a gun muzzle, a spray nozzle of any other application in which the projection of the nozzle must remain clear. The deflection of gases as just described can be used to provide a corrective force to the muzzle of a weapon as a means of stabilizing the weapon during automatic firing. Weapons under automatic fire are known to vary their elevation and have a tendency to creep upwards.

The concept of the instant curved lip deflector is predicted upon an under-expanded jet column which is normal for muzzle blast. The gas molecules leaving the muzzle are at super sonic velocity and follow paths, as shown in FIGS. 11 and 2, radiating from the muzzle. When these molecules encounter fluid at sub-sonic .velocity, there is a multiple collision deceleration of the molecules generating an abrupt velocity-temperaturedensity gradiant or shock. If the molecules encounter a solid surface, they rebound from that surface. if the rebound velocity is counter to the incident velocity, the shock will be produced upstream from the solid body. However, if the direction of the rebound velocity is within 9tlt of the incident velocity, as in the case of the instant invention, a turning of the flow will result from the ensuing collisions. The use of the concave, curved lip to deflect the muzzle blast flow is based upon the above concept combined with the need to inject the redirected flow into the undisturbed part of the muzzle blast in order to provide transverse momentum in the flow forming the shoclt bottle.

A continuation of a second deflecting vane to form a scroll case can be used for form a silencer. Such a silencer is shown in lFlG. 3.

F IG. 3 shows a means for diverting and collecting the flow from a supersonic under-expanded jet such as that formed by exhausting propelling gas from a weapon. This method may be used to silence the weapon and/or for collection of the propellant gas for use as a power source. FIG. 3 shows a weapon muzzle 30 having a bore or passage 31 and a curved deflecting lip 33 having a concave curved surface 34 and an end portion 38. The remaining portion of the muzzle 30 can be flat as at 32. Extending down from the lower portion of muzzle 30 is a support member 35 in which is secured a collecting lip 36 which terminates in an end portion 37 and a containing curved member 43 terminating in a lip portion 39. It will be noted that the end portion 38 of lip member 33 and end portion 37 of collecting lip 36 are not in the area of the projected bore or passage. In other words, both lips leave sufflcient room for a projectile to exit from a general area of the muzzle and deflector silencer.

The inclusion of the collecting lip in containing portion calls for collection of a muzzle gas flow after being deflected by portion 33. Such a collection of muzzle gas flow provides for velocity, pressure and temperature losses within lip 36, before gas discharge. Such a loss should greatly reduce the sound pressure level of the muzzle blast over-pressure waves. The portion 43 and lip 36 form a scroll case. This offers an advantage over conventional and current types of silencers which allow a portion of the higher pressure propellant gas to exhaust immediately following exit of the bullet from the silencer. The size and depth of the container area can be determined from knowledge of the propellant gas pressure at the muzzle of the weapon immediately prior to shot ejection.

Thus it is seen a novel muzzle blast deflector and silencer have been provided which do not affect performance of a projectile forced from a bore or passage of a weapon and which further work at full efficiency in obviating the basis for most of the common problems encountered with muzzle blast including noise.

While only one embodiment of the invention herein disclosed has been shown and described, it will be obvious to those of ordinary skill in the art that many changes and modifications may be made without departing from the scope of the intended claims in which:

We claim:

1. A combination of muzzle and flow deflector, said muzzle having a through bore therein, said flow deflector comprising a member mounted on the end of said muzzle and extending in front of the end of said muzzle, a portion of said member between the end of said bore and the end of said member having a concave surface which begins and ends in a plane parallel to said bore to effect deflection of a shock bottle normally caused by supersonic exhaust flow across the path of said bore.

2. A combination as in claim 1 further including a collecting means for said exhaust gases.

3. A combination as in claim 2 wherein said collecting means comprises a scroll container attached to said muzzle on the side opposite said deflector.