US2974910A - Blast fence - Google Patents

Description

B. S. LYNN BLAST FENCE March 14, 1961 2 Sheets-Sheet 1 Filed June 24, 1957 March 14, 1961 B. s. LYNN 2,974,910

BLAST FENCE Filed June 24, 1957 2 Sheets-Sheet 2 0 INI/EN roR. Z3 5er/7am ,Wan/ey Lynn United States, Parent" BLAST FENCE.

Bernard` Stanley Lynn, 19451 Black Road, Los Gatos, Calif.

Filed June 24, 1951, ser. No. 661,445

1z claims.. (ci. 244-114) This invention relates generally to blast fences for deilecting the blast from aircraft power units of the jet type.

Various structures, generally referred to as blast fences, have been used for deilecting the blast from power units o f the jet type. Such structures are desirable at the ends of runways where takeoff runs commence, and along test areas where units are being tested or repaired, or along run-up areas. A typical prior Iart blast fence employs a plurality of vertically spaced horizontal louvers or, vanes which intercept the blast and deflect it upwardly. Another prior type of fence is in the form of a chute which deilects the blast upwardly from its normal hori- Zontal direction. Such fence constructions, in contrast with the present invention, lack certain desirable features. Particularly they are relatively expensive to construct and install, and :after installation they are relatively unsightly. The overalll height is usually excessive, thus blocking the view from the cockpit of the aircraft. Although they deflect the blast upwardly at an inclination to the horizontal, they do not provide the degree of protection desired. In areas behind the fence, the jet noise is relatively heavy and the` air quite turbulent.

It is the general object of the present invention to provide a blast fence construction which overcomes the difficulties pointed out above.

Another object of the invention is to provide a blast fence which is relatively inexpensive and simple to construct and erect, and which when erected occupies a minimum amount of space. Another object is to provide a blast fencewhich alords more. complete protection for surrounding areas, ,incl'ujdlifngv particularly the area immediately behind the fence.`

Another object is to provide a fence construction which materially reduces the noise of the blast as received. in adjacent areas.

Another object is to provide a blast fence construction which can be made in sections :or units, which. are simple to transport and to connect together to form a fence of the desired length.

l Another object is to provide a fence construction which can be readily and quickly installed where desired, and' which can be readily removed4 and salvaged for reuse.

Another object is to provide a blast fence making usev offatnew principle, namely that of a vertical pneumatic curtain which provides greater protection for adjacent areas.l Another -.object is to.. provide a fence whichl is not subjecf'to excessive heating.Y Additional objects and features of the inventiontwill appear from the following description in which the preferred embodiments have-beenset forth in detail in conjiinctionwith-the accompanying drawing.

.Referringi tothe. drawing:

. fence of extended. length having end and transverse walls.

Figure 6 is a view similar to Figure 1 but showing a modication in which means is provided for cooling the device. f

Figure 7 is a view like Figure 3 but showing a modication.

The blast fence illustrated in Figures 1 and 2 consists of a main body 10 formed of sheet metal, and providing a blast deflecting surface. A suitable frame 11 serves to support the body and can consist of vertical posts 12, cross-connected by the beam 13. Suit-able means such as bolts 14 serve to attach the upper portion of the body to the beam 13, while the lower end mayv be attached to the anchoring bolts. 16, which are embedded in the anchoring block 17.

I prefer to form the body 1t) of sheet metal, and particularly sheet metal that is formed toa continuous curvature and stiifened by ribs or corrugations. V-In the particular construction illustrated in Figures l and 2 the corrugations extend vertically, and the curvature is such that as viewed in section, the body conforms substantially to the segment of a cylinder. To facilitate manufacture,v transporting the device, and its erection, it is desirable to form the body of a plurality of sections, as illustrated in Figure 2, the various sections having over-l lapping margins attached together by means of bolts or rivets 18. When dismantled the sections may be nested.

In -addition -to the main body it is desirable to provide the end w-alls 19. These walls can be shaped as shown in Figure 1', each with a curved edge attached to the body by suitable means such as bolts 21. The free edge can be reinforced tas by means of stiifening angles 22.

Means is provided for protecting the lower or leading edge of the corrugated sheet metal. Thus as shown in Figure 3, a sheet metal strip 2.3 extends for the lengthfof the fence, and is'bent to cover the lower edge fofthe corrugated metal in the manner shown. This strip.- pref sents an inclined face to a blast directed toward the,V fenceg, and blocks leakage of blast through the spaces ybeneath the raised portions of the corrugations.

A feature of my fence is the fact that the body-isl formed to deflect a blast. upwardly, and discharge it witha major vertical direction component. Preferably the deilecting surfaces are so formed that in addition to av major vertical direction component, at least a portion of the deflected blast has a minor direction component backwardly toward the direction of the blast. In Figure l this is accomplished by extending the upper edge to a level above the horizontal axis a, to which the body is formed. In practice it is convenient to form the body as a one-quarter segment of a cylinder, `and mount the body in the manner shown in Figure l, whereby the lower edge of the body is offset rearwardly with respect to the.y axis a. v

Figure 4 schematically'illustrates an area 24 where one" may desire. to test or warm up jet power units,y or whe-re jet aircraft may be located immediately prior-to* proceed-V4 ing along a runway. The blast upon striking the fence'is progressively deflected upwardly to discharge from the upper edge of the deliecting surface with a majorvert'b cal' direction component.

As may be noted from this and other figures, the height of the upper edge of the deflecting surface is greater than the transverse or front to back dimension.

With the construction illustrated in Figures 1 and 4, the indicated angle between a line tangent to the upper edge of the deflecting surface, and the vertical, is about 12. Therefore a minor horizontal direction component is imparted to the discharging gases, and this minor component is in a direction back toward the source of the blast. In practice this angle may range from about 6 to 20.

' As shown in Figure 7, the lower edge of the sheet metal body may be tangential to the ground surface. Thus in this instance the body 10a corresponds to a slightly greater than one-quarter cylindrical segment,

whereby its lower edge is substantially directly below the axis a. This avoids the use of a recess for receiving the lower edge of the corrugated sheet metal and the strip 23, and permits vertical mounting for the bolts 16.

When the blast from a jet power unit is directed toward the fence, a relatively thin layer of high velocity gas is formed close to that surface of the area 24 which intersects the cone 25 of the blast (Figure 4), and also close to the delecting surface of the fence. Another relatively thicker layer of gas, moving at a relatively lower speed, is present over the high velocity moving layer. The high velocity layer tends to discharge from the upper edge of the fence with a minor backwardly directed component as previously described. However, the slower moving layer, because of its relatively greater thickness, tends to spill over the upper edge of any deecting surface. With my invention, the high velocity relatively thin layer of gas which is discharged from the upper edge of my fense with a direction component backwardly toward the source of the blast, forms a pneumatic curtain which extends vertically from the fence, and which serves to effectively intercept slower moving gases which would otherwise find their way into the area to the rear of the fence to cause turbulence. Thus all of the gases of the blast are delivered upwardly with a major vertical direction component, thus providing complete protection in regions behind the fence.

It will be evident from the foregoing that my fence has a new principle of operation which makes possible cer tain new and advantageous results. As previously mentioned, complete protection is alforded against the gases of the blast in regions behind the fence. If dust and stones are caught up by the blast, they are delivered in a nearly vertical direction from the fence, thus avoiding an otherwise hazardous condition. When the fence is in operation there is a noticeable decrease in the noise level in adjacent areas, in contrast with prior art fences. This is attributed to the fact that the fence tends to effectively reflect sound waves upwardly, and in addition the high velocity pneumatic curtain `forms a zone which by virtue of sound absorption, sound reflection, or other acoustic effect, minimizes the intensity of noise from the blast in the area behind the fence.

The end walls 19 are desirable in that they prevent the discharge of a portion of the blast from the ends of the fence, thus causing all of the blast to be delivered upwardly. Without these end walls, it would be necessary to considerably extend the length of the fence for proper protection. The corrugated construction of the body aids in discharge of the high velocity layer in the desired direction to form a pneumatic curtain, and in addition provides a simple structure of the requisite strength. As previously described, such a body may be attached to thesupporting frame only along its upper edge portion, with the lower edge being anchored to a ground area.

Forming the body in a plurality of sections in the manner illustrated in Figure 2, facilitates manufacture and transportation. Such sections can be readily nested for transport and quickly erected to form a -fence of the desired length.

When the fence is in use the strip 23 prevents the leakage of gases and dirt under the `raised portions of the corrugations.

The height of the fence is not excessive, and as suggested should not be such as to block the view from the cockpit of the aircraft.

Since hot gases contact only one side of the sheet metal, the fence is not subject to excessive heating in normal usage, in contrast with fences of the vane type where both sides of the vanes are exposed to hot gases.

As shown in Figure 5, where the fence is of considerable length, it is desirable to use walls between the ends of the fence corresponding to the end walls 19 of Figure l. Thus as shown in Figure 5, intermediate vertical walls 19a are mounted at regular intervals between the walls 19, and serve to minimize lateral movement of the gases, thus causing the gases of the blast to be delivered upwardly in the desired manner.

In some instances the blast may be of such intensity and temperature as to cause undue heating of the corrugated metal. For such conditions I can employ the modication shown in Figure 6. Here a sprinkler pipe 26 is mounted adjacent the deflecting `strip 23, and is `connected to the water supply pipe 27. By the operation of the solenoid valve 28, water can be supplied to the sprinkler pipe 26 as desired, and the discharging sprays of water caused to wet the surface of the body 10, thus preventing excessive heating. Operation can be made automatic by providing a suitable thermal responsive ele ment 29, mounted in heat conducted relation with the body, and connected by electrical circuitry wires 31 to operate the solenoid valve 28. With this arrangement when the temperature rises to a predetermined value,

water is automatically supplied to wet the surface of the body 10.

I claim:

l. In a blast fence adapted to be installed on a ground area to receive and deect the blast from an aircraft power unit of the jet type, means forming a substantially continuous and impervious blast dellecting surface, said surface having at its bottom a horizontal leading edge and at its top an upper horizontal edge at a substantial elevation, said surface in vertical section being uniformly curved whereby a jet blast directed against the surface is deflected upwardly for final discharge from the upper edge.

2. A blast fence as in claim 1 in which said surface is formed by sections of corrugated sheet metal with the corrugations in parallel vertical planes and all straight lines touching the surface from side to side are horizontal and therefore parallel to both edges of the deflecting surface, whereby a jet blast directed toward the ysame is` edge with a major vertical direction component, said fence being closed at each end by a vertical plate to form an angularly disposed trough with said plates limiting lateral movement of the gases of the jet blasts.

3. In a blast fence adapted to be installed on a ground area to receive and deflect the blast from an aircraft power unit of the jet type, means forming a substantially impervious blast deecting surface, said surface having an upper horizontal edge at a substantial elevation, said surface being smoothly curved to ybe concave as viewed from the source of the blast, the curvature of said surface being roughly a quarter of a cylinder with its bottom edge parallel to the ground whereby a jet blast directed against the surface is directed upwardly, and the transverse horizontal dimension of said surface being less than the height thereof.

- 4. In a blast fence adapted to receive the deect the blast from an aircraft power unit of the jettype, a corrugated sheet forming a substantially impervious unbroken blast deecting surface, said surface having au upper horizontal edge at a substantial elevation but below the level of the cockpit of the aircraft, said surface being continuously curved to conorrn roughly to the quarter segment of a cylinder having a horizontal axis, whereby a jet blast directed toward the same is deflected upwardly for final discharge from the upper edge.

5. A blast fence as in claim 4 in which the upper horizontal edge of said surface is at an elevation above said horizontal axis, and the lower leading edge is parallel i to the upper edge and to the said aXisl and is substantially directly beneath the latter, whereby a jet blast directed toward the surface is deflected upwardly for final discharge from the upper edge with a major vertical direction component and a minor direction component of from to 20 backwardly toward the source of the blast.

6. The blast fence of claim 5 in which the minor component is roughhly 12 and the deecting surface is supported in part by a frame secured to the surface at a point below the upper edge and where the flow is vertical.

7. In a blast fence adapted to be installed on a ground area to receive and deect the blast from an aircraft power unit of the jet type, a plurality of connected unbroken corrugated metal sheets forming a substantially impervious blast deilecting surface, the surface of each sheet having a lower leading edge parallel to the ground surface and an upper edge parallel thereto at an elevation just below the cockpit of the jet aircaft, said surface being arcuately concave as viewed from the source of the blast and means for securing the connected sheets of the fence to the ground with the height of the upper edge greater than the transverse horizontal dimension of the arcuate surface.

S. A blast fence to receive the blast from a jet aircraft power plant positioned in front of the fence, comprising a frame secured to the ground, a Substantially continuous and impervious blast deflecting body having a lower leading edge and an upper edge rearwardly thereof, means for securing the body to the ground proximate its leading bottom edge to support the lower portion of the body, and means for securing an upper portion of the body to said frame to support said upper portion; said body having a surface smoothly curved in vertical section substantially tangent to a horizontal plane at its bottom leading edge and substantially tangent to a vertical plane at its upper portion whereby when said curved surface receives the top of the cone of the blast from the jet aircraft power plant at a level below the top of the body, the blast will be discharged upwardly from the top of the body, thereby protecting the area of the ground behind the fence by reducing the jet noise and minimizing turbulence there as the jet stream does not pass to the rear of the fence.

9. A blast fence as in claim `8 together with vertically 6 disposed plates secured to said body at each end of the fence and vertical intermediate walls between the end plates serving to block ow of gases laterally, that is, in a direction endwise of the fence, whereby all of the blast will be discharged upwardly from the top edge of the fence.

10. The fence of claim 8 in which the frame comprises posts bolted to the ground and a beam extending between the posts and bolted thereto; the leading bottom edge of the body is detachably secured to a vertical bolt anchored in the ground; the body is of corrugated sheet metal with the ribs and valleys of the corrugations in vertical planes; the curved surface is a portion of a cylinder, the axis of which is in a substantially vertical plane through the leading bottom edge of the body, and in a horizontal plane at about the level of the beam; the body is of connected similar sections;y each end of the fence is closed by a vertical plate; and intermediate walls parallel to the end plates prevent lateral movement of the gases of the jet blast.

1l. The fence of claim 8 in which the surface is approximately a quarter of a cylinder and the top of the fence is at a level below the cockpit of the usual airplane, whereby a relatively thin layer of the high velocity blast gases strikes the bottom of the body so that the arcuate surface defiects this high velocity layer to form a pneumatic curtain which intercepts the slower moving gases and causes all of the blast to be delivered upward, thus avoiding the use of a higher fence.

l2. In a blast fence adapted to be installed on a ground area to receive and dellect the blast from an aircraft power unit of the jet type, means forming a substantially impervious blast deilecting surface, said surface having an upper discharge edge and a lower horizontal leading edge, said surface being smoothly curved to be concave as viewed from the source of the blast, said means being of corrugated sheet metal with the ribs and valleys of the corrugations in vertical planes, the curvature of said surface being such that a jet blast directed against the surface is directed upwardly from the upper edge.

References Cited in the le of this patent UNITED STATES PATENTS 1,026,806 Iblings May 21, 1912 1,866,008 Burke July 5, 1932 1,925,139 Fellers Sept. 5, 1933 2,000,722 Steward May 7, 1935 2,608,363 Shumaker Aug. 26, 1952 2,646,257 Krume July 21, 1953 2,720,276 Droeger Oct. 11, 1955 2,726,830 Brown et al Dec. 13, 1955 2,826,382 Hayden Mar. 11, 1958

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