US 3147773 A
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1964 F. M. MATTHEWS ETAL 3,147,773
FLUID FLOW DIRECTING ARRANGEMENT AND METHOD OF OPERATION Filed Sept. 22, 1960 4 Sheets-Sheet 1 FLORENCE M. MATTHEWS PAUL K. SHUMPERT D INVENTORS Agent P 8, 1964 F. M. MATTHEWS ETAL 3,147,773
FLUID FLOW DIRECTING ARRANGEMENT AND METHOD OF OPERATION Filed Sept. 22, 1960 4 Sheets-Sheet 2 INVENTORS FLORENCE M. MATTHEWS PAUL K. SHUMPERT BY Agent v P 3, 1964 F. M. MATTHEWS ETAL 3,147,773
FLUID FLOW DIRECTING ARRANGEMENT AND METHOD OF OPERATION 4 Filed Sept. 22, 1960 4 Sheets-Sheet 3 BUTTERFLY 24 POSITION, N DEG.
0 IO 20 3O 4O 5O 6O BUTTERFLY 23 POSITION, '9- DEG.
7 f r 3 INVENTORS FLORENCE M. MATTHEWS PAUL K. SHUMPERT Agent FLUID FLOW DIRECTING ARRANGEMENT AND METHOD OF OPERATION Filed Sept. 22, 1960 F. M. MATTHEWS ETAL Sept. 8, 1964 4 SheetsSheet 4 on on 3 on o o. o J T duo 2 zoifiom nu himuCnm 'L ow on ov on 3 o. 0 0? I I \IIJDV/I 328% can. I Qzooum mzo m2; ZQEEEQ m INVENTORS FLORENCE M. MATTHEWS PAUL K.SHUMPERT ma-u oaaas amen:
Agent United States Patent s 147 773 FLUID FLow nmucfnt ANGEMENT AND Mnrnon or OPERATION Florence M. Matthews, Atlanta, and Paul K. Shumpert,
Smyrna, Ga, assignors to Lockheed Aircraft Corporation, Burbank, Calif. 7
Filed Sept. 22, 1%0, Ser. No. 58,604 3 Claims. (Cl. 137-637) This invention relates to a fluid flow directing arrangement, and more particularly a butterfly valve arrangement for directing any portion or all of a fluid flow from one system to another without materially effecting the fluid conditions upstream of the valve arrangement.
Diversion of a fluid flow or exhaust gas from a turbojet powerplant or other hot gas generator from one branch of a bifurcated duct system to another branch produces an effect or change in the fluid conditions upstream of the diversion point unless a diverting control arrangement is provided to avoid or substantially avoid such effects or changes. Heretofore, in an installation of a type as contemplated in copending application Serial No. 57, 656 (now Patent 3,085,770, dated April 16, 1963), entitled Aircraft Propulsion System and assigned to the same assignee as this application, with turbo-jet exhaust gas flowing through one branch of a duct system, the opening of another branch at the same time the one branch is closing for diversion of the turbo-jet exhaust gas from the one branch to the other, there results an increase in the effective nozzle area. Such increase of effective nozzle area in turn causes a sudden corresponding decrease in back pressure on the engine unless a most refined and complicated control system is incorporated for compensation of the back pressure decrease effects; such compensating control being desirable as this sudden decrease in back pressure provides an excess of available turbine energy which results in a rapid increase in engine speed. The initial engine acceleration has been calculated as being as high as 1000 revolutions/minute/ second or more, making such an arrangement or condition unsuitable or undesirable.
Another possible arrangement encompasses reduction of engine speed to or near idle conditions and then actuates the diversion mechanism: the result being considerable total time required for such diversion.
Accordingly, it is an object of this invention to provide a mechanical arrangement for diverting a fluid flow from one branch to another wherein the upstream conditions of the fluid are maintained substantially constant during the diversion operation.
A further object of this invention is to provide a mechanical arrangement for diverting fluid flow from one branch to another capable of diverting either all or part of the entering fluid flow.
It is another object of this invention to provide a mechanical arrangement for diverting fluid flow from one branch to another having applicability to both compressible and incompressible fluids.
A still further object of this invention is to provide a mechanical arrangement for diverting a fluid flow from one branch to another that has relative mechanical simplicity without adding undue complexity to a control system, and which is relatively easy and inexpensive to service and maintain.v
Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings in which:
FIGURE 1 is a partial cross-sectional view showing an aircraft propulsion gas flow system incorporating one embodiment of this invention;
FIGURE 2 is an enlarged view showing details of the embodiment of this invention shown in FIGURE 1;
r 3,147,773 Patented Sept. 8, 1964 Generally stated, the embodiment of the invention shown comprises a pair of butterfly valves cooperating to direct a fluid flow into one or either of two branch or duct passages. The two butterfly type valves are arranged to close off one passage while the other passage or branch is open and vice versa. In the installation shown the fluid flow is exhaust gas from a turbo-jet engine, and to maintain the substantially continuing thrust level during diversion of the fluid flow from one duct to the other it is most desirable, if not necessary, to maintain the fluid flow conditions upstream of the valves as constant as possible since the back pressure is a control parameter of the speed or r.p.m. of the engine, which in turn is a parameter of the engine thrust.
Referring more specifically to FIGURE 1, there is shown an aircraft propulsion system comprising a pair of power plants 7 whose combustion products or exhaust gases individually flow into exhaust ducts 8 and 8a. Both ducts 8 and 8a are bifurcated or split into two branches 9 and 10 and 9a and 10a respectively. Duct branch 9 has a propulsive nozzle 11 connected at the downstream end: the outlet of nozzle 11 arranged to direct propulsive flows for horizontal thrust. Likewise, a propulsive nozzle 12 is connected to the downstream end of duct branch 9a for discharging propulsive flows for horizontal thrust.
Duct branches 10 and 10a are both directed in an inboard direction and connected to ducts 13 and 14 respectively, the purpose and function of which forms no part of this present invention and is described in detail and claimed in copending application Serial No. 57,656,
and now Patent 3,085,770, dated April 16, 1963, as identified above.
Referring to FIGURE 2, butterfly valve 23 controls the fluid flow into duct branch 9a and nozzle 12, allowing the flow therethrough when in the open position as indicated by the full lines in FIGURE 2, and closing off the flow through duct branch 9a and nozzle 12 when valve 23 is in closed position 23a as indicated by phantomed lines in FIGURE 2. I
The fluid flow into duct branch 10a is controlled by a butterfly valve 24 which closes off any flow into duct branch 10a when in the closed position as indicated by the solid lines in FIGURE 2 and permits diversion of the fluid flow into duct branch 10a when in the open position 24a as indicated by phantomed lines in FIGURE 2.
Butterfly member 24 is provided with a camber for a cross-sectional aerodynamic shape to assist in directing the fluid flow into branch duct 10a when valve member 24 is open so as to reduce turning losses in the fluid.
Butterfly valve members 23 and 24 each have a crank 40 connected to the turning shafts thereof, each of the cranks 40 in turn connected to a control means 41 through rods or shafts 42. Control means 41 may be of any appropriate type to be actuated by any kind of power such as electrical, hydraulic, pneumatic, etc. as desired; the only requirement being it actuate both valves either simultaneously, or concurrently under any program schedule desired for the installation concerned. Likewise, the program schedule may be controlled by any appropriate arrangement such as mechanical linkages or cams, etc., which would result in only one actuator rod or shaft 42 being utilized.
In the application of the embodiment shown, it has been discussed as being most desirous and advantageous to provide for maintaining the back pressure on the engines as constant as possible during the actuation of the butterfly valves 23 and 24 to close 01f the open duct and open the closed duct. Such can be done by scheduling the butterflies 23 and 24 to operate dilferentially as indicated by curve 43 in FIGURE 3. The end portions43a and 43b of curve 43 are nonlineardue to the unsymmetrical operation of a butterfly type valve. As can be realized by a study of portions 43a and 43b of curve 43, to schedule control of butterfly members 23 and 24 to provide a constant tailpipe back pressure during actuation of the butterfly valves requires a considerable amount of control complexity in control means 41. A much simplified control schedule is obtained by utilizing a straight line control schedule incorporating the flat portion of curve 43 as indicated by schedule curve 44 in FIGURE 3. For the installation of the invention embodiment depicted in the drawings a control schedule of the type indicated by curve 44 would require the open valve to move in a closingdirection approximately 18.5 before the other valve starts to open. Thereafter, both valves would move together until the original open valve is completely closed. At that point the opening valve would continue to open an additional 18.5 to the fully opened position, it being further understood that the angles a and for butterfly valves 24 and 23 respectively are arcuately identical, in this case both being 60 degrees.
As is to be understood, utilization of a valve control schedule, as exemplified by curve 44 in FIGURE 3, does permit a slight fluctuation in the tailpipe back pressure, such back pressure fluctuation being a compromise to reduce the inherent actuating complexity if valve control schedule 43 was adhered to. This slight fluctuation in; tailpipe pressure results in a slight variation or change tions in a valve operating time of two seconds for the com plete cycle.
In operation, with the position of butterfly valves 23 and 24 as shown in FIGURES 2, 3, and 4, the fluid flow can be diverted from passage through duct branch 9a into duct branch 10a by actuation of control mechanism 41, which upon its following the valve control schedule as indicated, by curve 44 in FIGURE 3 would start butter-.
fly valve 23 closing without movement ofbutterfly valve 24. Upon valve 23 swinging through 18.5 of are 6 toward a closing position, both valves 23 and 24 would swing concurrently thereafter through 41.5 of arcs 6 and a respectively, valve 24 moving in an opening direc-.
tion. At that point valve 23 would be in the closed position 23a as seen in FIGURE 2 and valve 24 would continue rotating an additional 18.5 until it has assumed its full open position as represented by lines 24a in FIGURE 2. With the cross-sectional camber of valve 24 the fluid flow is then diverted into branch 10a with a minimum of fluid losses due to turning, as well as the diversion has been accomplished with a minimum disturbance of the tailpipe back pressure.
By referring to FIGURE 4 it can be seen that with a total valve cycle operation time of one second, upon the closing of the open valve without the opening of the closed valve there is a slight reduction in engine speed (amounting to approximately two percent) at the point where the closing valve attains its complete closing lead time over the opening valve. Thereafter as the two valves move concurrently the engine speed increases back to normal which is obtained when the closing valve is closed approximately 40 and the opening valve has opened approximately 215. Thereafter the engine speed drops again the same as encountered before as the closing valve approaches its full closed position which is when the opening valve has opened approximately 41.5 Thereafter the engine speed rises back to normal.
Thus it can be seen there is provided a relatively simple mechanical arrangement for diverting flows from a fluid source into one or the other of a bifurcated duct arrangement, such system or arrangement being capable of simple and eflicient operation and providing for a minimum of I fluid flow disturbances upstream of the diverting valves.
While a particular embodiment of the invention has been illustrated and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the invention and it I is intended to cover in the appended claims all such modifications and equivalents as fall within the true spirit and scope of this invention.
' What is claimed is:
' 1. A fluid flow diverting arrangement comprising in I combination: a main fluid conductor receiving a fluid supply, a first butterfly valve in said main conductor, a branch fluid conductor connected to said main conductor between the fluid supply receiving point and said first butterfly valve, a second butterfly valve in said branch coni ductor, said butterfly valves arranged whereby when one is closed the other is open, and a control means operating said first and second butterfly valves along a combined valve schedule in which the open valve is partially closed before'any movement of the closed valve whereafter both valves move concurrently in their respective directions until the originally open valve is fully closed and thereafter the opening valve moves to a full open position.
" 2. A fluid flow diverting arrangement as claimed in claim 1 wherein both valves have the same amount of movement between full open and full closed positions.
3. A fluid flow diverting arrangement as claimed in claim 1 wherein the closing valve rotates approximately 18.5 before the opening valve starts to move, and the opening valve rotates approximately 185 to reach its full open position after the closing valve is closed.
References Cited in'the file of this patent UNITED STATES PATENTS Germany of 1943