US3088414A

US3088414A - Self-adjusting contra rotating axial flow pumps and turbines

Info

Publication number: US3088414A
Application number: US61200A
Authority: US
Inventors: Ozgur Cahit
Original assignee: Dominion Engineering Works Ltd
Current assignee: Dominion Engineering Works Ltd
Priority date: 1960-10-07
Filing date: 1960-10-07
Publication date: 1963-05-07
Anticipated expiration: 1980-05-07
Also published as: GB933620A

Description

y 1963 c. OZGUR 3,088,414

SELF-ADJUSTING CONTRA ROTATING AXIAL FLOW PUMPS AND TURBINES Filed 001',- 7, 1960 INVENTOR.

CAH IT 0 ZGUR v United States Patent 3,088,414 SELF-ADJUSTING CONTRA ROTATING AXIAL FLOW PUMPS AND TURBINES Cahit Ozgur, Lachine, Quebec, Canada, assignor to Dominion Engineering Works Limited Filed Oct. 7, 1960, Ser. No. 61,200

3 Claims. (Cl. 103-94) This invention relates to new and improved hydraulic pump-turbines of the axial flow type and has particular reference to the provision of new and improved means for 1mproving the performance thereof and extending their useful range 'of operation by automatically eliminatmg the whirl component'of the velocity at the outlet of the runner.

In the past attempts have been made to reduce or correct the whirl at the outlet by employing fixed or adjustable guide vanes and separately driven contrarot-ating runners have been employed.

Where the fixed or adjustable guide vanes were used, it has been found that the correction of the whirl was made at the expense of additional friction losses. Also there was lack of adaptability and worsening of the per formance for reverse flow operation in regard to efficiency and also danger of cavitation and there also was lack of flexibility for certain operating conditions where fixed guide vanes were employed.

Where separately driven'contra-rotating runners were employed, the lack of adaptability and worsening of performance for reverse flow operation and danger of cavitation as well as the fact that the correction of the whirl was made at the expense of additional friction losses but to a lesser degree but this variable speed arrangement of the separately driven contra-rotating runners led to complicated and expensive design.

It is the object of the present invention to provide new and improved means for improving the performance of axial flow pump-turbines to extend their useful range of operation by eliminating automatically the whirl component of the velocity at the outlet of the runner, which arrangement is relatively simple and economical in construction yet efiicient in operation.

Referring to the drawings:

FIGURE 1 is a schematic view, partly in section, of a device embodying the invention;

FIGURE 2 is a fragmentary view of the device shown in FIGURE 1 on an enlarged scale; and

FIGURE 3 is a schematic end view of the planetary gear system.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout, the device shown comprises two coaxial runners A and B which are driven by a fixed speed shaft S through a planetary gear system, designated generally as P, and which gear system is so chosen that it distributes the power that under all established operating conditions the mechanical torque applied to runner A is equal and in the opposite direction to that applied to runner B.

According to the basic law of turbo-machinery, hydraulic torque-s developed by the two runners can only be equalized when the whirls imparted to the water by the runners are equal and in the opposite direction. In other words, in the case of straight inflow to runner A, equilibrium of the hydraulic torques is only possible when the whirl given to the water by runner A is taken out by runner B.

Since the mechanical torques delivered to the runners need always to be equal to the hydraulic torques developed, it leads to the conclusion that under all operating conditions, discharge and head, the two runners will take automatically the right speed to provide straight outlet flow from the machine when the inlet flow is straight.

Similarly, if the flow has an initial at the inlet of the machine, at the outlet. G and G are supporting ribs which carry the bearings of the runners. In the case that it is desirable to have an outlet flow with a slight whirlcomponent, the upstream ribs can be set at the necessary angle. Since the flow will have the same whirl at the outlet of the second runner the downstream ribs must be set at the same angle.

From the foregoing it will be seen that the pump will operate in the same manner when the flow is reversed provided that the shaft S is driven in the reverse direc-v tion.

When the device is running as a turbine, shaft S will be driven through the two runners, through the planetary gear system P and water going into the turbine with axial velocity will leave the second runner without having a whirl component.

The form of planetary system shown which is capable of transferring always equal and opposite torque to each of the runners and also suitable for a contra-rotating double coaxial runner arrangement comprises a gear 1 directly fastened to the main shaft S and rotates at the same speed n. Gear 4 is fastened to the stationary shaft F carried by support ribs 6;.

Disc 0 carrying the

planet gears

2 and 3 rotates idly about the main axis with a speed n and its short central shaft 7 is guided and supported by shafts F and S.

On the periphery of disc 0 are mounted several small shafts 8 on which planet gears 2' and 3 rotate idly. A plurality of such shafts 8 and sets of

gears

2 and 3 are provided, preferably 3. The internal ring gears 5 and 6 are fixed inside the runner hubs and the speeds of these gears are shown as n and n Positive direction for runner B being opposite to that of the main shaft.

A simple analysis of the above system leads to the following speed relation:

whirl component It will come out unaltered where D is the diameter of gears 5 and 6 and d that of the gears 1 and 4.

Note that in the case of D=2d, the speed of driving shaft S is four times greater than the main speed of runner-s A and B.

It will be seen that the present device comprises basically a hydraulic pump-turbine having two coaxial propellertype wheels of opposite hand with two fixed spiders attached to the wall of the throat with the shaft having a first simple planetary gear train attached thereto and comprising a sun gear attached to the shaft and a plurality of planet pinions operably mounted on a free spider and a ring gear attached to the first of the wheels, which wheel is journalled on the hub on the first of the fixed spiders and which shaft is also journalled in the hub of said first fixed spider and a second simple planetary gear train having substantially the same gear ratio as the first planetary gear train and comprises a sun gear fixed to the second of the fixed spiders and a plurality of planet pinions operably mounted on the free spider and a ring gear attached to the second of the wheels which wheel is journalled on the hub of the second of the fixed spiders.

It will be seen that with the present invention straight outlet flow is obtained for all operating conditions whereby efiiciency is improved for a very large range of operations and instability caused by swirling flow is eliminated, Also, in the case of relatively long discharge pipes, friction losses in pipes are reduced for pumps and there will be, in turbine operation, no radial pressure gradient to cause additional cavitation problem.

Furthermore, peak efiiciency of the unit is believed to be higher than pumps having one runner and one outlet straightening vain system due to the fact that in the latter, recoveries are made through the straightening vanes at the expense of extra losses while in the present invention no recovery of the whirl component is necessary.

It will also be seen that the present invention, for pump operation the head is split between the two runners and thus, cavitation conditions are improved and the need for an additional governing system is eliminated.

Furthermore, the driving system employed is simpler than that of the separate driven contra-rotating arrangement and versatility of the system can be so arranged as to provide the desirable speed ratio between the runners and the driving shaft.

The system is suitable for turbines, pumps, pump turbines and in both direct and reverse operation.

It will be seen that the arrangement can be modified to meet particular requirements such as, if it is desired to give the water a slight Whirl through the two runners, the planetary system can be chosen to supply a slightly different torque by giving gears 1 and 4 different diameters and making corresponding changes to the two planet gears. Also runners may have either variable or fixed blades and can either be built identical or to different design according to the requirements.

From the foregoing it will be seen that I have provided new and improved means for obtaining all of the objects and advantages of the invention.

I claim:

1. A hydraulic pump-turbine having two coaxial propeller-type wheels of opposite hand, a shaft, spider means for supporting said wheels in operable position and means connecting said wheels for power transmission to said shaft and to each other and to said spider means, said connecting means comprising two simple planetary gear trains employing a common free planet carrier.

2. A hydraulic pump-turbine having two coaxial propeller-type wheels of opposite hand, a shaft, spider means for supporting said wheels in operable position and means connecting said wheels for power transmission to said shaft and to each other and to said spider means, said connecting means including a pair of inter-connected planetary gear means such that the torques imparted to said wheels are equal.

3. A hydraulic pump-turbine having a throat and two coaxial propeller-type wheels of opposite hand, two fixed spiders attached to the wall of the throat, a shaft, a first simple planetary gear train comprising a sun gear attached to said shaft, a plurality of planet pinions operably mounted on a free spider and a ring gear attached to the first of said wheels which Wheel is journalled on the hub on'the first of said fixed spiders and said shaft is also journalled in the hub of said first fixed spider, a second simple planetary gear train having substantially the same gear ratio as the first planetary gear train and comprising a sun gear fixed to the second of said first spiders, a plurality of planet pinions operably mounted on said free spider and a ring gear attached to the second of said wheels which wheel is journalled on the hub of the second of said fixed spiders.

References Cited in the file of this patent UNITED STATES PATENTS 1,547,467 Swanson July 28, 1925 2,560,216 Coponat -a July 10, 1951 2,561,090 Baumann July 17, 1951 2,584,555 Cleave et a1. Feb. 5, 1952 2,689,681 Sabatiuk Sept. 21, 1954 2,955,747 Schwaar Oct. 11, 1960 3,038,307 Oprecht June 12, 1962 FOREIGN PATENTS 58,032 Netherlands Aug. 15, 1946 214,761 Germany Feb. 23, 1956 399,619 Great Britain Oct. 12, 1933 815,268 France Apr. 5, 1937 947,189 Germany Aug. 9, 1956 963,415- France Jan. 4, 1950

Claims

1. A HYDRAULIC PUMP-TURBINE HAVING TWO COAXIAL PROPELLER-TYPE OF OPPOSITE HAND, A SHAFT, SPIDER MEANS FOR SUPPORTING SAID WHEELS IN OPERABLE POSITION AND MEANS CONNECTING SAID WHEELS IN OPERABLE POSITION AND MEANS SHAFT AND TO EACH OTHER AND TO SAID SPIDER MEANS, SAID CONNECTING MEANS COMPRISING TWO SIMPLE PLANETARY GEAR TRAINS EMPLOYING A COMMON FREE PLANET CARRIER.