US3572285A - Wide band siren system - Google Patents

Abstract

A WIDE BAND NOISE SOURCE HAVING FOUR SIREN ROTOR BLADES POSITIONED IN CLOSE PROXIMITY TO EACH OTHER AND SUPPORTED WITHIN TWO RING SUPPORT MEMBERS WHICH ARE SECURED TO A BASE SUPPORT MEMBER. THE TWO OUTER ROTOR BLADES ARE EACH SUPPORTED ON JOURNAL MEMBERS IN TWO BEARINGS IN THE RING SUPPORT MEMBERS. THE TWO CENTER ROTOR BLADES ARE SUPPORTED ON SHAFT JOURNAL MEMBERS IN FOUR BEARING SUPPORTED WITHIN THE JOURNAL MEMBERS FOR THE TWO OUTER ROTOR MEMBERS. THE JOURNAL MEMBERS FOR THE FOUR ROTORS HAVE PULLEYS KEYED TO THEM SO THAT THE FOUR ROTORS CAN BE DRIVEN THROUGH V-BELTS BY FOUR ELECTRIC MOTORS. LABYRINTH SEALS ARE PROVIDED TO KEEP DUST PARTICLES AND DIRT AWAY FROM THE BEARINGS.

Description

March 1971 H. F. WOLFE 3,572,285

WIDE BAND SIREN SYSTEM Filed Nov. 5, 1969 5 Sheets-Sheet 1 March 23, 1971 H. F. WOLFE 3,572,285

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WIDE BAND SIREN SYSTEM Filed Nov. 5, 1969 5 Sheets-Sheet 4 E-L- j [NV/INTO R. fl n/co F- w B)" 7%? arr-0e (y March 23, 1971 H. F. WOLFE 3,572,285

WIDE BAND SIREN SYSTEM Filed Nov. 5, 1969 5 Sheets-Sheet 5 BY W United States Patent Office 3,572,285 WIDE BAND SIREN SYSTEM Howard F. Wolfe, Kettering, Ohio, assignor to the United States of America as represented by the Secretary of the Air Force Filed Nov. 5, 1969, Ser. No. 874,167 Int. Cl. G01k 7/00 US. Cl. 116-147 3 Claims ABSTRACT OF THE DISCLOSURE A wide band noise source having four siren rotor blades positioned in close proximity to each other and supported within two ring support members which are secured to a base support member. The two outer rotor blades are each supported on journal members in two hearings in the ring support members. The two center rotor blades are supported on shaft journal members in four bearings supported within the journal members for the two outer rotor members. The journal members for the four rotors have pulleys keyed to them so that the four rotors can be driven through V-belts by four electric motors. Labyrinth seals are provided to keep dust particles and dirt away from the bearings.

BACKGROUND OF THE INVENTION Various types of sirens have been developed for the generation of high intensity wide band noise. One such device is shown in FIGS. 6 and 6a of the patent to Cole et al. 3,072,094. Certain problems exist in devices of this type due to the high radial and axial loads on the bearings due to bending stress induced in the rotor due to fluctuation of the air pressure load on the rotor blades.

A device of the type shown in the patent to Cole et al. is shown and described in Technical Report AFFDL-TR- 66-8, March 1966 Design and 'Performance of 15 Kw. Wide 'Band Acoustic Facility," available from Defense Documentation Center, No. AD 634,904. As pointed out on page 4 of the technical report, rotor speeds vary between 625 r.p.m. and 5,000 r.p.m. As can be seen from the fourth paragraph, on page 4, when adjacent rotors are counter rotated the relative speed on the bearings between the rotors is the sum of speeds of the rotors or at 5,000 r.p.m. rotor speed, the speed seen by the bearings between the rotors is 10,000 r.p.m. For the large bearings used the suggested maximum speed for long life of the bearings is 6,300 r.p.m. Thus an increase over this speed, such as when the relative speed is 10,000 r.p.m., will shorten the life of the bearings.

SUMMARY OF THE INVENTION According to this invention external support is provided instead of supporting the rotors on a central shaft as in the device of the report. Thus the larger bearing between the support and the outer rotor sees only the relative speed between the outer rotor journal and the stationary support and the bearings which experience the larger relative rotation between the two rotor shafts have a smaller diameter and therefore can withstand greater relative speeds.

IN THE DRAWINGS FIG. 1 is a partially schematic end view of the rotor assembly for a wide band noise source according to the invention;

FIG. 2 is a reduced schematic top view of the device of FIG. 1;

FIG. 3 is a partially cutaway side view of the rotor unit for the device of FIGS. 1 and 2;

FIG. 4 is an end view of one of the rotor elements of the device of FIG. 1;

FIG. 5 is an end view of a second rotor element of the device of FIG. 1;

3,572,285 Patented Mar. 23, 1971 DESCRIPTION OF THE INVENTION Reference is now made to FIGS. 1 and 2 of the drawings which show a wide band noise generator 10 having four rotors shown schematically at 12, 13, 14, and 15. The rotors 12 and 13 are supported by a ring support housing member 16 and the rotors 14 and 15 are supported by ring support housing member 18, as will be described later. The housing 16 is supported on a support frame shown generally at 20 by means of flanges 21 and 22. The housing 18 is supported on support frame 20 by means of flanges 23 and 24. Air is supplied to the rotors by means of five air passages shown schematically at 19".

The rotor 12, having blades 12 as shown in FIG. 7, is supported within the housing 16 by means of a hollow journal member 25 which runs in bearings 27 and 28. Spacers 29 are positioned between bearings 27 and 28. The journal member 25 is secured to the rotor 12 by means of bolts 30, one of which is shown in FIG. 3.

The rotor 13, having blades 13 as shown in FIG. 6, is supported within journal member 25 by means of a shaft journal member 32, which is keyed to the rotor, and four bearings 34, 35, 36, and 37. A spacer 38 is located between bearings 35 and 36.

Rotor 12 is driven by means of a pulley member 40 which is keyed to the journal member 25, and the rotor 13 is driven by a pulley member 42 which is keyed to shaft 32.

The rotor 15, having blades 15 as shown in FIG. 4, is supported within housing 18 by means of hollow journal member 47 secured to the motor by means of bolts 49, one of which is shown, and two bearings 50, one of which is shown. The rotor 14, having blades 14' as shown in FIG. 5, is supported within the journal member 47 by means of a shaft journal member 52 keyed to the rotor 14 and four bearings 53, two of which are shown. Rotor 15 is driven by a pulley 57 keyed to journal member 47 and rotor 14 is driven by a pulley 55 keyed to shaft 52. As shown in FIG. 8, the rotors 12, 13, 14, and 15 are driven by individual electric motors 60, 61, 62, and 63, respectively, through V-belts which engage pulleys 40, 42, 55, and 57. The rotors 12, 13, 14, and 15 are all dynamically balanced to within .01 ounce inch at 5,000 r.p.m.

Labyrinth seals 43, 44, and 45 keep dust and other foreign matter from reaching the bearings 27, 28, 34, 35, 36, and 37.

In the operation of the device, the rotors are driven by electric motors 60, 61, 62, and 63 in the same manner as in the technical report referenced above. The rotors 12 and 14 are driven in one direction and the rotors 13 and 15 are driven in the opposite diection. Air, from air supply 58, is supplied to the rotors through passages 19, shown schematically at 19' in FIG. 1, in about the same manner as in the referenced technical report except that five passages 19 are described whereas only four passages are dc scribed in the report. However, the number of passages amounts to a matter of design. The small horn sections 64 feed a large horn section 65 as in the reference technical report. The direction of air flow in FIG. 3 is shown by the arrow 59. The speed of the individual electric motors need not be the same and may be varied through a range of speeds for some applications.

There is thus provided a wide band noise source which is more rugged and which produces longer bearing life than prior art devices.

I claim:

1. A wide band noise source comprising a base support member; a first ring support member secured to said base support member; a second ring support member secured to said base support member in predetermined fixed spaced relation to said first ring support member; a first rotor member having a plurality of blades positioned in a predetermined angular relation around the periphery thereof; means for rotatably supporting said first rotor within said first ring support member; a second rotor member having a plurality of blades positioned in a predetermined angular relation around the periphery thereof; means for rotatably supporting the second rotor member Within the support means for said first rotor member; a third rotor member having a plurality of blades positioned in a predetermined angular relation around the periphery thereof; means for rotatably supporting the third rotor member within said second ring support member; a fourth rotor member having a plurality of blades positioned in predetermined angular relation around the periphery thereof; means for rotatably supporting the fourth rotor member within the support means for said third rotor member; said first, second, third, and fourth rotor members being positioned in close proximity to each other; means for driving the first and third of said rotor members at predetermined speeds in one direction; means for driving the second and fourth of said rotor members at predetermined speeds in the opposite direction; means for directing at least one high velocity air stream through the blades of said rotors.

2. The device as recited in claim 1 wherein said means for supporting said first and third rotor members within said first and second ring support members are hollow shaft journals secured to the first and third rotors and mounted in bearings Within the ring support members and the means for supporting the second and fourth rotors are shaft journals secured to the second and fourth rotors and mounted in bearings Within said hollow shaft journals.

3. The device as recited in claim 2 wherein the relative angular position of the blades on said rotors is different on each of the rotors and wherein air is directed through the rotors at a plurality of spaced positions around the rotors.

References Cited UNITED STATES PATENTS 2,222,322 11/1940 Schmacke 340-405 2,912,958 11/1959 Von Gierke et a1. 116147 3,072,094 1/1963 Cole et a1 116-147 OTHER REFERENCES Publication: Technical Report AFFDL-TR-668, March 1966, Design and Performance of 15 Kw., Wide Band Acoustic Facility, Defense Documentation Center, No. AD 634,904.

LOUIS J. CAPOZI, Primary Examiner US. Cl. X.R.

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