JPH0893722A - Swirl preventive shape of suction waterway - Google Patents

Abstract

PURPOSE: To increase critical flow velocity by forming the outside of a bending part of a suction waterway so as to smoothly contact from inside with an extension line having a throat diameter in an almost perpendicularly curving suction waterway. CONSTITUTION: A downstream part 5 of a curved part 4 of a suction waterway 3 is formed so as to smoothly contact from inside with a straight line. A inside part 6 of the curved part 4 is also smoothly connected to a throat part 2 so as to correspond to an outside part 5. Therefore, since the downstream part 5 of the curved part 4 smoothly contacts from inside with the throat part 2, a flow S becomes a largely and smoothly curved flow S1 in the curved part 4, and flows in the throat part 2. Therefore, a swirl by a reversal flow as usual is not generated. As a result, critical velocity of flow speed Vs can be increased to about three times of usual critical velocity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vortex preventive shape of a suction water passage in a pump.

[0002]

2. Description of the Related Art In a conventional pump, as shown in FIG. 2, a suction water passage 10 is normally bent at a substantially right angle in a throat portion 2 of an impeller 1, and an outside of the bent portion 11 has a throat diameter De extended. Since the straight line L was in contact with the outside from the outside, the bulging portion 12 shown by the hatched portion was formed.

[0003]

In the conventional suction water passage 10, when the flow velocity vs is increased, the flow s is increased by the bulging portion 12.
As shown in the figure, there is a problem that a vortex is generated as a reverse flow s1, and there is a limit to the increase of the limit flow velocity.

It is an object of the present invention to provide a vortex preventive shape of a suction water passage which speeds up a critical flow velocity.

[0005]

According to the present invention, in the suction water channel which is bent at a substantially right angle in the throat portion, the outside of the bent portion of the suction water channel is formed so as to be in contact with the extension line of the throat diameter smoothly from the inside. are doing.

[0006]

In the vortex preventive shape of the suction water passage configured as described above, the curved portion smoothly contacts the throat portion from the inner side, so that the flow bends largely and smoothly into the throat portion. Therefore, the vortex due to the reverse flow is not generated unlike the conventional case. As a result, the limit flow velocity can be increased.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, parts corresponding to those in FIG. 2 are designated by the same reference numerals, and duplicated description will be omitted.

In FIG. 1, the downstream portion 5 of the bent portion 4 of the suction water passage 3 is formed so as to smoothly contact the straight line L from the inside. The inner portion 6 of the bent portion 4 is also smoothly connected to the throat portion 2 so as to correspond to the outer portion 5.

Next, the operation will be described.

In the suction water passage 3, the downstream portion 5 of the curved portion 4 is in contact with the throat portion 2 from the inside smoothly, so that the flow S becomes a flow S1 that is largely and smoothly bent in the curved portion 4. It flows into the throat section 2.
Therefore, a vortex due to the reverse flow s1 unlike the conventional case does not occur. As a result, according to the experiment, the limit flow velocity of the flow velocity Vs can be increased to about three times that of the conventional one.

[0012]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, a large flow can be made to flow smoothly into the throat, vortices can be prevented and the critical flow velocity can be increased.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a side sectional view showing a conventional shape.

[Explanation of symbols]

 De ... Throat diameter L ... Straight line that extends the throat diameter S, S1, s ... Flow s1 ... Reverse flow 1 ... Impeller 2 ... Throat part 3, 10 ... Suction Water channels 4, 11 ... Bent portion 5 ... Outside portion 6 ... Inside portion 12 ... Swelling portion

Claims (1)

[Claims] 1. A vortex of a suction water channel, characterized in that, in a suction water channel that bends at a substantially right angle in a throat portion, the outside of the curved portion of the suction water channel is formed so as to smoothly contact the extension line of the throat diameter from the inside. Preventive shape.