JP3494730B2 - Vertical axis hydraulic machine suction pipe - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injecting high-pressure air into a runner chamber for accommodating a runner rotating about a vertical axis to thereby reduce the water in the runner chamber. The present invention relates to a vertical-axis hydraulic machine that drains water into a suction pipe continuously provided below the water pipe and pushes down the water surface below the runner to cause the runner to idle in the air. 2. Description of the Related Art In the daytime, water stored in a dam flows down to a discharge pond to generate electricity, and at night, excess power is used to pump water from the discharge pond to a dam. Type power plants are widely known. In such a pumping type power plant, a vertical pump turbine 1 as schematically shown in FIG.
Is used. In this type of pump turbine 1,
In order to stabilize the power system and quickly respond to changes in power demand, the runner 2 of the pump turbine 1 is run idle.
The so-called phase adjustment operation is often performed for a long time. When performing the phase adjustment operation when the pump-turbine 1 is operated as a pump, first, the movable guide vane 3 is fully closed, and then high-pressure air is supplied into the runner chamber 4. Is pushed back into the suction pipe 5 to push down the water surface 6 by a predetermined distance from the lower end 7 of the runner 2.
The runner 2 is idled in the air to reduce the rotational driving torque of the runner 2. [0003] However, the air in the space 8 between the runner 2 and the water surface 6 is swirled in the rotation direction of the runner 3 by the rotation of the runner 3, so that the air on the water surface 6 is large as shown in FIG. 9. Rippling and swinging occur. As a result, the water in the suction pipe 5 is scattered and adheres to the runner 2, causing a rotational imbalance in the runner 2, causing a sudden increase in rotational vibration, and a swinging water surface 6 entering the runner 2. A part of the high-pressure air supplied into the runner chamber 4 due to a sudden increase in the rotational driving torque of the runner 2 or furthermore due to the swinging of the water surface 6 flows downstream of the suction pipe 5 through the elbow portion 5 a of the suction pipe 5. Leakage may occur toward the side 5b, and supply of high-pressure air into the runner chamber 4 may not be able to keep up. In order to prevent the swing of the water surface 6 from affecting the runner 2, it is conceivable to take a sufficient size in the height direction of the suction pipe 5.
In addition to the increase in size and cost, the construction cost for burying such a large suction pipe 5 is greatly increased. [0004] In order to solve the above-mentioned problems, Japanese Patent Publication No. 60-44515 and Japanese Utility Model Laid-Open Publication No. 59-111972 disclose the position of the water surface 6 by defining the position. A technique for minimizing the height dimension of the draft tube has been disclosed, but this technology is intended for those with a small level of water penetration head in the draft tube. Not suitable for simple pump turbines. Further, Japanese Patent Publication No. 4-78837 and Japanese Patent Application Laid-Open No. 55-156274 disclose a technique in which high-pressure water or high-pressure air is jetted into a suction pipe in order to suppress the fluctuation of the water surface. Not only are new piping and control equipment required to eject high-pressure water or high-pressure air, but also high reliability is required for piping and control equipment to handle high-pressure water or air. Not in. Further, the applicant of the present application has previously filed an application for a technique for defining the height of the suction pipe using the Froude number corrected by the air density in the suction pipe (Japanese Patent Application No. 2-585).
No. 04) does not mention the relationship between the height difference between the runner and the water surface and the vibration and drive torque of the runner. Japanese Patent Application Laid-Open Nos. 56-106069 and 5-195941 disclose techniques for installing fins for suppressing water surface swing in a suction pipe. Since it always protrudes into the suction pipe, it may be damaged by the water pressure pulsation of the water flow, or may interfere with the operation at normal times and adversely affect the operation performance. Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to increase the rotational vibration of the runner or increase the runner rotation when the water surface in the suction pipe is pushed down to cause the runner to idle in the air. Not only does the driving torque not increase, but also the water surface swings greatly and the high-pressure air injected into the runner chamber does not leak downstream from the elbow of the suction pipe, and is stable for a long time It is an object of the present invention to provide a suction pipe of a vertical axis hydraulic machine capable of performing a phase adjusting operation. [0009] In order to achieve the above object, the present invention introduces a dimensionless coefficient K which correctly indicates the energy of rocking of a water surface pushed down into a suction pipe, and By a test or the like, an appropriate relationship between the height difference between the runner and the depressed water surface and the dimensionless coefficient K, and an appropriate relationship between the height difference between the depressed water surface and the elbow portion of the suction pipe and the dimensionless coefficient K, It is a thing that found a relationship. That is, in the suction pipe of the vertical-axis hydraulic machine according to the first aspect of the present invention, the water in the runner chamber is filled by injecting high-pressure air into a runner chamber that houses a runner rotating around the vertical axis. In a suction pipe of a vertical axis hydraulic machine, the water is drained into a suction pipe continuously provided below the runner chamber, and the surface of the water is pushed down below the runner so that the runner idles in air. The diameter of the outlet part facing the suction pipe is De (m), the outer peripheral speed of the outlet part is Ue (m / sec), and the height from the depressed water surface to the lower end of the runner is Z1.
( M ) the suction pipe is horizontal below the runner
Push down from the top end in the elbow that bends in the direction
The height to the given water surface is Z2 (m), and the density of the high-pressure air in a state where the water surface is pushed down is ρ _a (kg /
m ³ ) and the density of water in the suction pipe are ρ _w (kg / m
³ ) With the gravitational acceleration being g (m / sec ² ),
A = Z1 / De for dimensionless coefficient A , B = Z for dimensionless coefficient B
2 / De, the dimensionless Froude number Fr is expressed as Fr = Ue / (g ×
De) ^1/2 , and the dimensionless coefficient K is K = (ρ _a / (ρ _w −ρ _a ))
^When each is defined as ^1/2 × Fr, A ≧ 0.74K +
The value of Z1 that satisfies the relationship 0.26 and B ≧ 1.11
The height dimension of the draft tube is set corresponding to the value of Z2 satisfying the relationship of K + 0.29 . According to the suction pipe of the hydraulic machine according to the first aspect of the present invention, even when the water surface swings, the rotational vibration of the runner rapidly increases or the runner rotation driving torque increases rapidly. The height difference between the runner and the depressed water surface can be clearly defined so that it does not increase , and the depressed water surface swings greatly , and the high-pressure air injected into the runner chamber is discharged from the elbow of the suction pipe. since Ru can be clearly defined difference in height between the uppermost end of the water surface and the elbow depressed so that it can be prevented from leaking toward the downstream side,
The height dimension of the suction pipe can be appropriately set. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a suction pipe of a vertical hydraulic machine according to the present invention will be described below in detail with reference to the drawings. In the following description, the same parts will be denoted by the same reference numerals, and description thereof will be omitted. As shown in FIG. 1, when a pump-turbine 1 as a vertical-axis hydraulic machine to which the present invention is applied operates as a pump, a so-called phase-shifting operation in which the runner 2 idles in the air is performed. After the movable guide vane 3 is fully closed, high-pressure air is supplied into the runner chamber 4, and water in the runner chamber 4 is pushed back into the suction pipe 5 so that the water surface 6 is moved from the lower end 7 of the runner 2. Also push down. In this state, the height difference between the water surface 6 and the lower end 7 of the runner 2 is Z1 (m), and the water surface 6 and the elbow portion 5a of the suction pipe 5 are set.
The height difference from the uppermost end portion 5c is defined as Z2 (m). The diameter of the outlet portion of the runner 2 facing the suction pipe 5 is De (m), and the outer peripheral speed of the outlet portion is Ue.
(M / sec), the gravitational acceleration is g (m / sec ² ), and the density of the high-pressure air with the water surface 6 depressed is ρ
_a (kg / m ³ ) and the density of water in the suction pipe 5
_w (kg / m ³ ) and gravitational acceleration g (m / sec ² ). Further, the dimensionless coefficient A is expressed as The dimensionless coefficient B is given by Dimensionless Froude number Fr The dimensionless coefficient K is given by Are defined respectively. A model of such a pump-turbine 1 is manufactured, and a phase adjustment operation in which the value of the dimensionless coefficient K is variously changed is performed.
FIG. 2 shows the results of measuring the magnitude of vibration of the upper cover 4a of the runner chamber 4 and the amount of high-pressure air leaking from the elbow section 5a of the suction pipe 5 to the downstream side 5b. FIG. 2 shows the dimensionless coefficients A and B on the horizontal axis, the magnitude of vibration of the upper cover 4a on the right vertical axis, and the leakage amount of high-pressure air on the left vertical axis. When the value of K is K = 1.02 and K = 1.22, the change in the magnitude of the vibration of the upper cover 4a is indicated by a dotted line, and the change in the amount of high-pressure air leaked is indicated by a solid line. . As is apparent from FIG. 2, the vibration of the upper cover 4a (dotted line)
And the leakage amount of the high-pressure air (solid line) can be divided into a region where it is almost constant and a region where it increases rapidly.
The boundary portion can be separated by a straight line A and a straight line A shown in FIG. On the other hand, FIG. 3 shows a region where the vibration of the upper cover 4a or the runner rotation driving force which shows a phenomenal change substantially similar to this vibration does not suddenly increase, and the dimensionless coefficient K is plotted on the horizontal axis. And the hatching is shown on a graph in which the dimensionless coefficient A is plotted on the vertical axis. As is apparent from FIG. 3, the region where the vibration of the upper cover 4a or the runner rotation driving force does not suddenly increase corresponds to the upper left side of the straight line represented by A = 0.74K + 0.26 in FIG. Can be represented. Accordingly, if the value of the dimensionless coefficient K is obtained from the dimensions of the runner 2 and the operating conditions of the pump turbine 1, the value of A, that is, the value of Z1, is set so that A ≧ 0.74K + 0.26. Should be determined. Then, by determining the height dimension of the suction pipe 5 so that the height difference between the water surface 6 to be pushed down and the runner lower end 7 can be set to Z1, the vibration of the upper cover 4a or the runner rotation driving force suddenly decreases. It is possible to obtain a suction pipe of a vertical hydraulic machine that does not increase. Similarly, FIG. 4 shows the area where the amount of high-pressure air leaks sharply increases on a graph in which the dimensionless coefficient K is plotted on the horizontal axis and the dimensionless coefficient B is plotted on the vertical axis. It is represented by adding. As is apparent from FIG. 2, the region where the amount of high-pressure air leakage does not increase rapidly can be expressed as the upper left side of the straight line represented by B = 1.11K + 0.29 in FIG. . Therefore, if the value of the dimensionless coefficient K is obtained from the dimensions of the runner 2 and the operating conditions of the pump turbine 1, the value of B, that is, the value of Z2, is such that B ≧ 1.11K + 0.29. Should be determined. Then, the shape of the elbow portion 5a of the suction pipe 5 is determined so that the height difference between the depressed water surface 6 and the uppermost end portion 5c in the elbow portion 5a of the suction pipe 5 can be set to Z2.
It is possible to obtain a suction pipe of a vertical axis hydraulic machine in which the amount of high-pressure air supplied into the runner chamber 4 leaking from the elbow section 5a of the suction pipe 5 toward the downstream side 5b does not increase sharply. That is, in the pump turbine 1 of this embodiment , the dimensionless coefficient A is A ≧ 0 based on the dimension of the runner 2 of the pump turbine 1 and the value of the dimensionless coefficient K obtained from the operating conditions of the pump turbine 1. 0.74K + 0.26
And the dimensionless number coefficient B is B ≧ 1.1
Since the value of Z2 is determined so as to be 1K + 0.29, and the dimension in the height direction of the suction pipe 5 is set so as to satisfy these values of Z1 and Z2, the upper cover 4a Vibration or runner rotation driving force may increase rapidly, or high pressure air may flow through the elbow 5a of the suction pipe 5.
The amount of water leaking toward the downstream side 5b from the water turbine does not suddenly increase, and the pump turbine 1 can be stably operated for a long period of time in a stable manner. Since the suction pipe of the vertical hydraulic machine of the present invention is constructed as described above, high-pressure air is injected into the runner chamber, the water surface is pushed down into the suction pipe, and the runner is placed in the air. When performing the phase-shifting operation in which the idler is performed, the water surface oscillates greatly and the water scatters and adheres to the blades of the runner, causing rotational imbalance and increasing the rotational vibration of the runner, and the runner blades oscillate Not only does the runner rotational drive torque not suddenly increase due to the collision with the water surface, but also the high-pressure air injected into the runner chamber does not leak downstream from the elbow portion of the suction pipe. Therefore, according to the present invention, it is possible to provide a suction pipe of a vertical hydraulic machine capable of performing a phase adjustment operation stably for a long time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view schematically showing a main part of an embodiment of a suction pipe of a vertical hydraulic machine according to the present invention. FIG. 2 shows the dimensionless coefficients A and B on the horizontal axis, the magnitude of vibration of the upper cover of the runner chamber on the right vertical axis, and the amount of high-pressure air leaked on the left vertical axis.
Is a diagram in which, when K = 1.02 and K = 1.22, the change in the magnitude of the vibration of the upper cover is indicated by a dotted line, and the change in the leakage amount of high-pressure air is indicated by a solid line. FIG. 3 is a diagram in which a dimensionless coefficient K is plotted on the horizontal axis and a dimensionless coefficient A is plotted on the vertical axis, and a region where runner driving torque does not increase sharply is hatched. FIG. 4 shows the dimensionless coefficient K on the horizontal axis and the dimensionless coefficient B on the vertical axis, and hatches a region where the leakage amount of the high-pressure air supplied into the runner chamber does not suddenly increase. FIG. FIG. 5 is a longitudinal sectional view schematically showing a main part of a suction pipe of a conventional vertical hydraulic machine. [Description of Signs] 1 Pump-turbine 2 Runner 3 Guide vane 4 Runner chamber 5 Suction pipe 5a Elbow section 5b of suction pipe 5b Downstream section 5c of suction pipe Top end 5d inside elbow section 5e Inside wall face of suction pipe 5e Storage recess 5f Penetration Hole 6 Depressed water surface 7 Runner lower end 8 Space between runner and water surface 9 Rotation axis

Continuation of the front page (56) References JP-A-2-157481 (JP, A) JP-A-2-201070 (JP, A) JP-A-3-260375 (JP, A) , U) JP 60-44515 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F03B 11/00 F03B 3/10

Claims (1)

(57) [Claim 1] High-pressure air is injected into a runner chamber for accommodating a runner rotating around a vertical axis, so that water in the runner chamber is connected below the runner chamber. Drain in the suction pipe, and the water surface is pushed down below the runner so that the runner idles in the air.In the suction pipe of the vertical hydraulic machine, the diameter of the outlet part of the runner facing the suction pipe is De
(M), the outer peripheral speed of the outlet portion is Ue (m / sec), the height from the depressed water surface to the lower end of the runner is Z1 (m), and the suction pipe is horizontally folded below the runner.
The water pushed down from the top end in the elbow
The height to the surface is Z2 (m), the density of the high-pressure air when the water surface is depressed is ρ _a (kg / m ³ ), the density of water in the suction pipe is ρ _w (kg / m ³ ), The gravitational acceleration is g (m / sec ² ), the dimensionless coefficient A is A = Z1 / De, the dimensionless coefficient B is B = Z2 / De, and the dimensionless Froude number Fr is Fr = Ue / (g × D
e) ^1/2, the dimensionless coefficient _{K K = (ρ a / (} ρ w -ρ a)) 1/2 × Fr, and when defining each of Z1 satisfying A ≧ 0.74K + 0.26 the relationship value your
And Z2 satisfying the relationship of B ≧ 1.11K + 0.29
A suction pipe for a vertical axis hydraulic machine, wherein a height dimension of the suction pipe is set according to a value.