DE302588C - - Google Patents

Description

(N 1

For special purposes, when using centrifugal pumps, the condition placed that large amounts of water are promoted to small heads and small amounts of water to high heads should.

The latter condition has hitherto been sought to achieve that the centrifugal pumps with two impellers, which are connected in series for large amounts of water and small delivery head, on the other hand connected in series work with a small amount of water and a higher delivery head. Through this arrangement the pumps became very heavy in weight and confusing in design. Also when switching the pumps to different work areas are always appropriate large changeover devices to use.

The present invention now shows how it is possible using only a single one Impeller to meet the conditions mentioned.

The new centrifugal pump has an impeller A of special design connected to a stator B, the blades of which are adjustable.

Design of the impeller: It denotes: among other things _, peripheral speed in the outer impeller diameter Da, u _e peripheral speed in the inner impeller diameter De, w _a the absolute exit velocity, w _e the absolute entry velocity, v _a the relative entry velocity, v _a the relative exit velocity.

So the i is the general form of the main equation for centrifugal pumps:

In the case of the impellers of the usual design, v _e > v _a is now generally made, so that

the Member

Ve '

■ Va *

becomes positive.

In the impeller of the present Erfindüng ^x is departed from this rule, by changing the relative discharge velocity is _a made larger than the relative inlet v

III

Ve *

-Va *

speed v _e so that the limb
becomes negative. If, for example, i / „= 2Oni,» _e = iom, then the term is = -15 m. So the delivery head to be achieved is determined by the

element

Ve ²

influenced in such a way that

that compared with the same peripheral speed. normal training of the impeller the delivery head to be achieved decreases by about 15 m with the same amount of water.

The term = z -15 m is now

used to increase the delivery head with smaller amounts of water.

Assuming that only ¹ Z _{3 of} the previously pumped amount of water is to be lifted, then v _a = 6.66 tn, v _e = 3.33 m and

Consequently

Ve

2

Va *

- 1.62. So it will be with the

smaller amount of water, which should be ¹ Z _{8 of} the first assumed, the delivery head increases by 15 - 1.62 = 13.38 m due to the influence of the relative speed.

If it is now also possible, a considerable amount with the impeller as described To achieve a gain in head with a small amount of water, the head around the impeller is increased further known diffuser arranged with rotatable blades.

It is possible to use the rotating blades with a smaller amount of water and a constant amount of water Speed to increase the delivery head by 20 to 30 percent.

In this particular case, the rotating guide vane should not be used for regulation the amount of water, but in connection with the impeller described above to increase it the delivery head can be used for small amounts of water.

Claims (2)

Patent Claims: r. Centrifugal pump, characterized in that the inlet and outlet cross-sections of the impeller in the blade channel are designed in such a way that the relative exit speed is greater than the relative entry speed by one to achieve a large increase in pressure with a small delivery rate. 2. Centrifugal pump according to claim 1, characterized in that the impeller is surrounded by rotatable guide vanes known per se, in order to achieve a further increase in pressure with a constant number of revolutions and to achieve a smaller delivery rate.