CN114542483A - A Calibration Device for Flow Coefficient of Balance Orifice of Centrifugal Pump Impeller - Google Patents

Abstract

A calibration device for flow coefficient of a balance hole of an impeller of a centrifugal pump is a pressure testing unit consisting of a 1# pressure measuring hole 9, a 1# pressure measuring cavity 8, a 1# pressure measuring conduit 16, a 1# screw joint 17, a 1# pressure hose 19, a 1# ball valve 21, a 2# pressure measuring hole 12, a 2# pressure measuring cavity 11, a 2# pressure measuring conduit 31, a 2# screw joint 18, a 2# pressure hose 20, a 2# ball valve 25, a pressure stabilizing tank 24, an exhaust valve 22 and a positive and negative pressure gauge 23, and realizes accurate measurement of inlet and outlet pressures of the balance hole 36 when the impeller 3 and the balance hole 36 rotate at high speed. The leakage rate test unit consisting of the drainage cavity 13, the water conduit 47, the backflow cavity 27, the electromagnetic flowmeter 29, the balance cavity 14 and the balance hole 36 is closed-loop, and can measure the leakage rate of the pump in operation under any working condition and cavitation state. The device has the advantages of simple structure and practical function, and can realize the measurement of the leakage amount of the balance hole 36 and the calibration of the flow coefficient of the balance hole 36 without repeatedly disassembling a testing device, so the operation is extremely convenient, and the time and the labor are saved.

Description

A Calibration Device for Flow Coefficient of Balance Orifice of Centrifugal Pump Impeller

technical field

The invention belongs to the field of pump technology detection, and in particular relates to a calibration device for a flow coefficient of a centrifugal pump impeller balance hole.

Background technique

In the design of centrifugal pump, a sealing ring is often attached to the impeller, and several balance holes are opened on the impeller to balance the axial force. When the centrifugal pump is working, a part of the high-pressure liquid at the outlet of the impeller flows back to the inlet of the impeller through the rear pump cavity, the gap of the rear sealing ring, the balance cavity and the balance hole in turn, forming the leakage of the side cavity of the rear cover plate of the impeller. It can be known from the fluid mechanics continuity equation that the leakage of the side cavity of the impeller rear cover plate is equal to the leakage of the balance hole. Accurately calculating the leakage of the balance hole according to the flow coefficient of the balance hole is a prerequisite for predicting the axial force, studying the influence mechanism of the high-speed jet of the balance hole on the cavitation performance of the pump, and reducing the volume loss of the pump, saving energy and reducing emissions. The equilibrium orifice flow coefficient can only be estimated by empirical formula, and the estimation result has a large error. Therefore, it has very important engineering application value to calibrate the equilibrium orifice flow coefficient by the method of experiment. To calibrate the flow coefficient of the balance hole, it is necessary to accurately measure the leakage of the balance hole and its inlet and outlet pressure. However, since the impeller rotates with the pump shaft at high speed, it is extremely difficult to directly measure the leakage of the balance hole and its inlet and outlet pressures.

After searching, the literature on calibrating the equilibrium orifice flow coefficient is as follows:

Chinese Journal of Agricultural Engineering "Test and Analysis of Liquid Leakage from Balance Hole of Centrifugal Pumps" (Volume 33, Issue 7, 2017), based on the fact that the leakage of the rear seal ring gap is equal to the leakage of the balance hole, an indirect measurement of the leakage of the balance hole is proposed. method, and calibrated the equilibrium orifice flow coefficient with different head coefficients. Specifically: open a liquid leakage hole on the stuffy cover of the balance chamber, first close the liquid leakage hole and open the balance hole, let the liquid in the balance chamber flow into the impeller inlet through the balance hole, and measure the pressure at the inlet of the rear seal ring gap and the balance chamber. Then block the balance hole, open the liquid leakage hole to lead the balance chamber liquid to the outside world, and open the back seal ring gap inlet pressure and balance chamber pressure and balance hole by repeatedly adjusting the liquid leakage hole and the opening of the gate valve on the pump outlet pipeline. When the pressure is equal, the flow rate of the liquid leakage hole is the leakage amount of the balance hole. This method basically realizes the indirect measurement of the leakage of the balance hole, but the disadvantage is that the liquid in the balance chamber is led to the outside, and the pressure at the outlet of the liquid leakage hole is atmospheric pressure, while in the cavitation state, the inlet of the impeller is negative pressure, so This method cannot measure the balance hole leakage when the pump is cavitated.

The Journal of Huazhong University of Science and Technology (Natural Science Edition) "Calculation and Experimental Research on Leakage and Pressure of Centrifugal Pump Balance Chamber" improves the leakage test device, and calibrates the flow coefficient of the balance hole with different specific areas according to the test results. It connects the balance chamber with the pump inlet pipeline through the return water pipeline. When the balance hole is blocked, the balance chamber liquid returns to the pump inlet, and the closed-loop measurement of leakage is initially realized. Since the test device is closed, indirect measurement of the leakage of the balance hole in the cavitation state can be achieved. The disadvantage of this device is that it leads the balance chamber liquid to the pump inlet, and the flow state at the impeller inlet changes greatly when the balance hole is opened or blocked, which directly changes the external characteristics of the pump and Cavitation performance, so the test results of leakage in the cavitation state of the pump have a large error.

The test devices in the above two documents have the following shortcomings: on the one hand, when measuring the leakage of the balance hole, it is necessary to open the balance hole for pressure measurement, and then block the balance hole to measure the pressure. The test steps are cumbersome and require multiple disassembly tests. On the other hand, when calibrating the flow coefficient of the balance hole, the pressure of the balance chamber and the pump inlet pressure are used to replace the inlet and outlet pressure of the balance hole respectively. In fact, the pressure in the balance cavity of the centrifugal pump is not evenly distributed during operation, and the inlet pressure of the pump is also quite different from the outlet pressure of the balance hole, so the accurate calibration of the flow coefficient of the balance hole cannot be achieved.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the present invention aims to provide a calibration device for the flow coefficient of the balance hole of a centrifugal pump impeller, which mainly includes a stator part, a rotor part, a pressure test unit and a leakage test unit. The stator part consists of pump body, rear pump cover, front sealing ring, rear sealing ring, through cylinder, 2# skeleton seal, 3# skeleton seal; the rotor part consists of pump shaft, impeller, balance hole plate, balance hole, 1# skeleton Seal, key and round nut; the pressure test unit consists of 1# pressure hole, 1# pressure chamber, 1# pressure pipe, 1# wire joint, 1# pressure hose, 1# ball valve, 2# pressure Hole, 2# pressure measuring chamber, 2# pressure measuring conduit, 2# wire joint, 2# pressure hose, 2# ball valve, pressure tank, exhaust valve, positive and negative pressure gauge; the leakage test unit is composed of drainage It consists of a cavity, a water diversion pipe, a return cavity, an electromagnetic flowmeter and a balance cavity.

Among the stator components, the rear pump cover is composed of two parts, the left large ring and the right cylinder, and the rear pump cover is fixed on the right side of the pump body by the A group of bolts. The front sealing ring is installed on the inner side of the pump body by means of interference fit, the rear sealing ring is installed on the left end of the cylinder on the right side of the rear pump cover by means of interference fit, and the left end face of the rear sealing ring is connected with the large ring of the rear pump cover. the left end face is flush. The through cylinder is fixedly connected to the right side of the rear pump cover through the B group bolt and nut assembly. There is a certain gap between the left end face of the through cylinder and the right side wall of the impeller rear cover plate. It starts from the left end face of the through cylinder and runs along the shaft inside the through cylinder. There are two inner steps processed from left to right, and the inner step surface is perpendicular to the central axis. The 2# skeleton seal is positioned and installed on the inner wall of the penetrating cylinder on the right side of the inner step surface of the first stage of the penetrating cylinder through the spigot, and the left end face of the 2# skeleton sealing is flush with the inner step surface of the first stage of the penetrating cylinder. The 3# skeleton seal is positioned and installed on the inner wall of the penetrating cylinder on the right side of the inner step surface of the second stage of the penetrating cylinder through the stop, and the left end face of the 3# skeleton sealing is flush with the inner step surface of the second stage of the penetrating cylinder.

In the rotor part, the impeller is fixedly mounted on the pump shaft through a key. In order to reduce the interference of the impeller reserved hole on the liquid flow state at the outlet of the balance hole, the diameter of the impeller reserved hole should be as large as possible, so as to be enough to make the balance hole The left end face of the 1# pressure hole is included and will not damage the strength of the impeller hub. The balance orifice plate is positioned on the pump shaft and key through the spigot on the impeller hub. Starting from the right end face of the balance orifice plate, two levels of outer steps are machined on the outside of the balance orifice plate along the axial direction from right to left, and the outer step surface is perpendicular to the central axis. The left outer surface of the balance orifice plate is matched with the sealing lip of the 2# skeleton seal, the right outer surface of the balance orifice plate is matched with the sealing lip of the 3# skeleton seal, and the first step surface on the right side of the balance orifice plate is matched with the 3# skeleton seal There is a gap at the left end of the . The impeller and the balance hole disc are axially fixed on the pump shaft by a round nut. The balance hole is horizontally opened on the balance hole plate along the axial direction. The 1# skeleton seal is installed on the inner side of the impeller seal ring, the left end face of the 1# skeleton seal is fitted with the rear cover of the impeller, and the sealing lip of the 1# skeleton seal is matched with the outer surface of the left side of the through cylinder.

In the pressure test unit, the 1# pressure taking hole is an inverse L-shaped hole vertically opened in the left part of the balance hole plate along the radial and axial directions, which can transmit the outlet pressure of the balance hole to the 1# pressure measuring chamber. 1# The number of pressure holes is equal to the number of balance holes. The impeller rear cover, the balance orifice plate, the 2# skeleton seal, the first step surface of the penetrating cylinder, the inner wall of the penetrating cylinder, and the 1# skeleton seal enclose the 1# pressure measuring chamber. The 1# pressure-measuring conduit is set on the transparent cylinder, the left end of the 1# pressure-measuring conduit is communicated with the 1# pressure-measuring chamber, and the right end of the 1# pressure-measuring conduit is communicated with the left end of the 1# pressure hose through the 1# pair of wire joints. The right end of the 1# pressure hose is communicated with the surge tank through the 1# ball valve. The 2# pressure taking hole is a short hole vertically opened on the right part of the balance hole plate along the radial direction, which can transmit the inlet pressure of the balance hole to the 2# pressure measuring chamber. The number of 2# pressure taking holes is equal to the number of balance holes. The outer surface of the balance orifice plate, the second outer step surface of the balance orifice plate, the 3# skeleton seal, the second step surface of the through-tube, the inner wall of the through-tube, and the 2# skeleton seal enclose the 2# pressure measuring cavity. The 2# pressure measuring conduit is horizontally opened on the through-tube along the axial direction, the left end of the 2# pressure measuring conduit is connected with the 2# pressure measuring chamber, and the right end of the 2# pressure measuring conduit is connected to the left end of the 2# pressure hose through the 2# pair of wire joints. Unicom. The right end of the 2# pressure hose is communicated with the surge tank through the 2# ball valve. An exhaust valve is installed on the upper end of the surge tank, and a positive and negative pressure gauge is installed on the right side of the surge tank.

In the leakage test unit, the outer surface of the through cylinder, the left surface of the through cylinder flange, the inner wall surface of the cylinder on the right side of the rear pump cover, the right end face of the rear seal ring, the impeller seal ring and the 1# skeleton seal are enclosed. Drainage cavity. Two water diversion pipes are symmetrically and fixedly installed on both sides of the cylinder on the right side of the rear pump cover along the radial direction, and the symmetrical central axes of the two water diversion pipes are at the same height as the central line of the pump shaft. The flange on the left side of the water diversion pipe is butted with the flanges on both sides of the cylinder on the right side of the rear pump cover, and is fixedly connected with the bolt and nut assembly of group E. The flange on the right side of the water diversion pipe is butted with the flanges on both sides of the return chamber, and is fixedly connected with the F group bolt and nut assembly. The left flange of the return chamber is butted with the right flange of the electromagnetic flowmeter, and is fixedly connected with the D group of bolts and nuts. The left flange of the electromagnetic flowmeter is butted with the right flange of the through cylinder, and is fixedly connected with the bolt and nut assembly of group C. The inner wall surface of the through cylinder, the 3# skeleton seal, the balance hole disc, the round nut, and the right end face of the pump shaft form a balance cavity, and the balance hole connects the balance cavity with the impeller inlet.

Compared with the prior art, the present invention has obvious beneficial effects.

1. After the leaking liquid flows out from the gap of the rear sealing ring, it flows back from the balance hole to the impeller inlet through the leakage test unit, which is exactly the same as the real flow direction of the leakage in the centrifugal pump. Therefore, the measurement of the leakage of the balance hole in the present invention is based on the condition that does not affect the flow state of the impeller inlet, the test device will not affect the external characteristics and cavitation performance of the pump, and the test results are highly reliable. The leakage of the pump can be measured under any flow conditions and cavitation conditions.

2. The pressure test unit can realize the accurate measurement of the pressure at the inlet and outlet of the balance hole when the impeller and the balance hole rotate at high speed, which provides a technical guarantee for the accurate calibration of the flow coefficient of the balance hole.

3. The structure of the present invention is simple and practical, the measurement of the leakage of the balance hole and the calibration of the flow coefficient of the balance hole can be realized without repeatedly disassembling the test device, and the operation is extremely convenient, saving time and effort.

Description of drawings

FIG. 1 is a schematic diagram of the structure and function of the present invention.

FIG. 2 is a top view of the test device of FIG. 1 .

In the picture: 1. Front sealing ring 2. Impeller reserved hole 3. Impeller 4. Impeller rear cover 5. Rear pump chamber 6. Rear pump cover 7. Group A bolts 8. 1# pressure measuring chamber 9. 1# Pressure hole 10. Balance orifice plate 11. 2# pressure measuring cavity 12. 2# pressure taking hole 13. Drainage cavity 14. Balance cavity 15. Drainage cavity outlet 16. 1# pressure measuring catheter 17. 1# pair of wire connectors 18. 2# Wire Connector 19. 1# Pressure Hose 20. 2# Pressure Hose 21. 1# Ball Valve 22. Exhaust Valve 23. Positive and Negative Pressure Gauge 24. Pressure Stabilizer 25. 2# Ball Valve 26. Return Chamber Inlet 27. Backflow chamber 28. Group D bolt and nut assembly 29. Electromagnetic flowmeter 30. C group bolt and nut assembly 31. 2# pressure measuring conduit 32. Through tube 33. B group bolt and nut assembly 34. Round nut 35. 3# skeleton Seal 36. Balance hole 37. Key 38. Back seal ring clearance 39. Back seal ring 40. 2# frame seal 41. Impeller seal ring 42. 1# frame seal 43. Pump body 44. Pump shaft 45. Group E bolts and nuts Assembly 46. Group F bolt and nut assembly 47. Drain pipe.

Detailed ways

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

As shown in Figures 1 and 2, a device for calibrating the flow coefficient of a centrifugal pump impeller balance hole mainly includes a stator part, a rotor part, a pressure test unit and a leakage test unit, wherein: the stator part consists of a pump body 43, a rear pump Cover 6, front sealing ring 1, rear sealing ring 39, through cylinder 32, 2# skeleton seal 40, 3# skeleton seal 35; the rotor part consists of pump shaft 44, impeller 3, balance hole disc 10, balance hole 36, 1 #skeleton seal 42, key 37, round nut 34; the pressure test unit consists of 1# pressure taking hole 9, 1# pressure measuring chamber 8, 1# pressure measuring conduit 16, 1# pair of wire joints 17, 1# pressure hose 19. 1# ball valve 21, 2# pressure hole 12, 2# pressure measuring chamber 11, 2# pressure measuring conduit 31, 2# wire joint 18, 2# pressure hose 20, 2# ball valve 25, surge tank 24. The exhaust valve 22, the positive and negative pressure gauges 23 are composed; the leakage test unit is composed of the drainage chamber 13, the drainage pipe 47, the return chamber 27, the electromagnetic flowmeter 29, and the balance chamber 14.

As shown in Figures 1 and 2, the rear pump cover 6 in the stator part is composed of two parts, a large ring on the left and a cylinder on the right. The front sealing ring 1 is installed on the inside of the pump body 43 by interference fit, the rear sealing ring 39 is installed on the left end of the cylinder on the right side of the rear pump cover 6 by interference fit, and the left end face of the rear sealing ring 39 is connected to the rear The left end face of the 6 large rings of the pump cover is flush. The through cylinder 32 is fixedly connected to the right side of the rear pump cover 6 through the B group bolt and nut assembly 33, and there is a certain gap between the left end face of the through cylinder 32 and the right side wall surface of the impeller rear cover plate 4, starting from the left end face of the through cylinder 32, Two levels of inner steps are machined on the inner side of the through cylinder 32 along the axial direction from left to right, and the inner step surface is perpendicular to the central axis. The 2# skeleton seal 40 is positioned and installed on the inner wall of the penetrating cylinder 32 on the right side of the inner step surface of the first stage of the penetrating cylinder 32 through the stop, and the left end face of the 2# skeleton sealing 40 is flat with the inner step surface of the first stage of the penetrating cylinder 32 together. The 3# skeleton seal 35 is positioned and installed on the inner wall of the penetrating cylinder 32 on the right side of the inner step surface of the second stage of the penetrating cylinder 32 through the stop opening. .

As shown in Figure 1, the impeller 3 in the rotor part is fixedly installed on the pump shaft 44 through the key 37. When installing the impeller 3, the contact surface between the impeller 3 and the shaft shoulder should be coated with sealant. An impeller reserved hole 2 is provided at a position with a smaller radius on the impeller rear cover plate 4. In order to reduce the interference of the impeller reserved hole 2 to the liquid flow state at the outlet of the balance hole 36, the diameter of the impeller reserved hole 2 should be as large as possible. It should be sufficient to include the balance hole 36 and the left end face of the 1# pressure taking hole 9 without damaging the strength of the impeller 3 hub. The balance orifice plate 10 is positioned and installed on the pump shaft 44 and the key 37 through the stop on the hub of the impeller 3. When installing the balance orifice plate 10, the contact surface of the balance orifice plate 10 and the impeller rear cover plate 4 should be coated with sealant. Starting from the right end face of the balance orifice plate 10, two outer steps are machined on the outside of the balance orifice plate 10 from right to left along the axial direction, and the outer step surface is perpendicular to the central axis. The left outer surface of the balance orifice plate 10 is matched with the sealing lip of the 2# skeleton seal 40, and the right outer surface of the balance orifice plate 10 is matched with the sealing lip of the 3# skeleton seal 35. The first stage on the right side of the balance orifice plate 10 There is a gap between the step surface and the left end of the 3# skeleton seal 35. The impeller 3 and the balance orifice plate 10 are axially fixed on the pump shaft 44 by the round nut 34 . The balance hole 36 is horizontally opened on the balance hole plate 10 along the axial direction. The 1# skeleton seal 42 is installed on the inner side of the impeller seal ring 41 , the left end face of the 1# skeleton seal 42 fits with the impeller rear cover 4 , and the sealing lip of the 1# skeleton seal 42 matches the left outer surface of the through cylinder 32 .

As shown in Figure 1, the 1# pressure taking hole 9 in the pressure test unit is an inverted L-shaped hole vertically opened in the left part of the balance orifice plate 10 in the radial and axial directions, which can transmit the outlet pressure of the balance hole 36 to the 1# tester. in the pressure chamber 8. The number of 1# pressure taking holes 9 is equal to the number of balance holes 36 . The impeller rear cover 4, the balance orifice plate 10, the 2# skeleton seal 40, the first step surface of the through cylinder 32, the inner wall of the through cylinder 32, and the 1# skeleton seal 42 enclose the 1# pressure measuring chamber 8. 1# measurement The pressure conduit 16 is set on the transparent cylinder 32, the left end of the 1# pressure measuring conduit 16 is communicated with the 1# pressure measuring chamber 8, and the right end of the 1# pressure measuring conduit 16 is connected to the left end of the 1# pressure hose 19 through the 1# pair of wire joints 17 Unicom. The right end of the 1# pressure hose 19 communicates with the surge tank 24 through the 1# ball valve 21 . The 2# pressure taking hole 12 is a short hole vertically opened in the right part of the balance orifice plate 10 in the radial direction, which can transmit the inlet pressure of the balance hole 36 to the 2# pressure measuring chamber 11. The number of the 2# pressure taking hole 12 is related to the balance hole. 36 are equal in number. The outer surface of the balance orifice plate 10, the second outer step surface of the balance orifice plate 10, the 3# skeleton seal 35, the second step surface of the through cylinder 32, the inner wall of the through cylinder 32, and the 2# skeleton seal 40 enclose the 2# measurement The pressure chamber 11. The 2# pressure measuring catheter 31 is axially and horizontally opened on the transparent cylinder 32, the left end of the 2# pressure measuring catheter 31 is communicated with the 2# pressure measuring chamber 11, and the right end of the 2# pressure measuring catheter 31 passes through the 2# pair of wires. The joint 18 communicates with the left end of the 2# pressure hose 20 . The right end of the 2# pressure hose 20 communicates with the surge tank 24 through the 2# ball valve 25 . An exhaust valve 22 is installed on the upper end of the surge tank 24 , and a positive and negative pressure gauge 23 is installed on the right side of the surge tank 24 . The surge tank 24 can eliminate the adverse effect of pressure pulsation on the pressure test results.

As shown in Figures 1 and 2, in the leakage test unit, the outer surface of the through cylinder 32, the left surface of the flange of the through cylinder 32, the inner wall surface of the cylinder on the right side of the rear pump cover 6, the right end face of the rear sealing ring 39, The impeller seal ring 41 and the 1# skeleton seal 42 enclose the drainage cavity 13 . Two water diversion pipes 47 are fixedly installed on both sides of the right cylinder of the rear pump cover 6 symmetrically in the radial direction, and the symmetrical central axes of the two water diversion pipes 47 are at the same height as the central line of the pump shaft 44 . The flange on the left side of the water diversion pipe 47 is butted with the flanges on both sides of the cylinder on the right side of the rear pump cover 6 , and is fixedly connected with the bolt and nut assembly 45 of the E group. The flange on the right side of the water diversion pipe 47 is butted with the flanges on both sides of the return chamber 27, and is fixedly connected with the bolt and nut assembly 46 of the F group. The left flange of the reflux chamber 27 is butted with the right flange of the electromagnetic flowmeter 29, and is fixedly connected with the bolt and nut assembly 28 of the D group. The flange on the left side of the electromagnetic flowmeter 29 is butted with the flange on the right side of the through cylinder 32 , and is fixedly connected with the bolt and nut assembly 30 of the C group. The inner wall surface of the through cylinder 32, the 3# skeleton seal 35, the balance hole plate 10, the round nut 34, and the right end face of the pump shaft 44 enclose the balance chamber 14, and the balance hole 36 communicates the balance chamber 14 with the inlet of the impeller 3.

Hereinafter, the working process of the present invention will be described in detail with reference to the accompanying drawings.

The measurement of the pressure at the inlet and outlet of the balance hole 36 is achieved as follows:

即为平衡孔36进口处的压力。然后，关闭2#球阀25打开1#球阀21，此时平衡孔36出口处的液体压力，依次经1#取压孔9、1#测压腔8、1#测压导管16、1#对丝接头17、1#压力软管19、1#球阀21传递到稳压罐24，则正负压力表23的读数

即为平衡孔36出口处的压力。As shown in Figure 1, start the centrifugal pump, and after the pump runs stably, open the 2# ball valve 25, and the liquid at the inlet of the balance hole 36 passes through the 2# pressure hole 12, 2# pressure chamber 11, and 2# pressure measurement conduit 31 in turn. , 2# wire joint 18, 2# pressure hose 20, 2# ball valve 25 flow into the surge tank 24, slowly open the exhaust valve 22 to exhaust the air in the surge tank 24. After the air is exhausted, close the exhaust valve 22. At this time, the liquid in the entire pressure measuring pipeline no longer flows. The liquid pressure in the pressure measuring pipeline is transmitted by static pressure. The readings of the positive and negative pressure gauges 23

That is, the pressure at the inlet of the balance hole 36 . Then, close the 2# ball valve 25 and open the 1# ball valve 21. At this time, the liquid pressure at the outlet of the balance hole 36 passes through the 1# pressure taking hole 9, 1# pressure measuring chamber 8, 1# pressure measuring conduit 16, 1# in turn. The wire joint 17, 1# pressure hose 19, and 1# ball valve 21 are transmitted to the surge tank 24, then the reading of the positive and negative pressure gauge 23

That is, the pressure at the outlet of the balance hole 36 .

The measurement of the leakage from the balance hole 36 is achieved as follows:

的大小。由于泄漏量测试单元是闭环的，后泵腔5内的泄漏液体从后密封环间隙38流出，经泄漏量测试单元最后从平衡孔36回流到叶轮3进口处，这与真实离心泵内泄漏量的流向是完全相同的。因此，所述的泄漏量测试单元对泄漏量的测试，是基于不影响叶轮3进口流态的情况下完成的，其测试装置不会对泵的外特性和空化性能产生影响，测试结果可信度高，可以测量泵的任何工况和泵在空化状态运行时的泄漏量。As shown in Figures 1 and 2, after starting the centrifugal pump, a part of the high-pressure liquid at the outlet of the impeller 3 enters the drainage chamber 13 through the rear pump chamber 5 and the rear sealing ring gap 38 in turn, and then enters the drainage pipe 47 from the outlet 15 of the drainage chamber, The water flows from the inlet 26 of the return cavity into the return cavity 27 through the water diversion pipe 47 , and the liquid flow direction changes in the return cavity 27 and flows out from the left outlet of the return cavity 27 . The liquid flowing out of the return chamber 27 flows into the inlet of the impeller 3 through the electromagnetic flowmeter 29 , the balance chamber 14 and the balance hole 36 in sequence, forming the leakage of the balance hole 36 . At this time, the indication value of the electromagnetic flowmeter 29 is the leakage amount of the balance hole 36

the size of. Since the leakage test unit is closed-loop, the leaked liquid in the rear pump chamber 5 flows out from the gap 38 of the rear seal ring, and finally flows back from the balance hole 36 to the inlet of the impeller 3 through the leakage test unit, which is consistent with the actual leakage in the centrifugal pump. The flow direction is exactly the same. Therefore, the leakage test by the leakage test unit is completed without affecting the flow state of the inlet of the impeller 3, and the test device will not affect the external characteristics and cavitation performance of the pump, and the test results can be With high reliability, it can measure any working condition of the pump and the leakage of the pump when it is running in a cavitation state.

The calibration of the flow coefficient of the balance hole 36 is realized as follows:

的计算公式，具体为：Huazhong University of Science and Technology (Natural Science Edition) "Calculation and Experimental Research on Leakage and Pressure of Balance Chamber of Centrifugal Pumps" gives the leakage of balance hole 36

The calculation formula is as follows:

为平衡孔流量系数；

为平衡孔过流断面总面积；

为液体密度。where:

is the equilibrium orifice flow coefficient;

is the total area of the flow cross section of the balance hole;

is the liquid density.

、平衡孔36出口处的压力

、平衡孔36泄漏量

代入上式，并将实测的平衡孔36过流断面总面积

和液体密度

一并代入，即可反推出既定条件下的平衡孔36的流量系数。The pressure at the inlet of the balance hole 36 measured above is

, the pressure at the outlet of the balance hole 36

, balance hole 36 leakage

Substitute into the above formula, and use the measured total flow cross-sectional area of the balance hole 36

and liquid density

By substituting them together, the flow coefficient of the balance hole 36 under a given condition can be reversed.

If you want to calibrate the flow coefficient of the balance hole 36 under the conditions of different shapes, different tapers, and different length-diameter ratios, you only need to process the balance orifice disc 10 of different forms, and the operation is very convenient.

Claims (5)

1. A calibration device for the flow coefficient of a centrifugal pump impeller balance hole, mainly comprising a stator part, a rotor part, a pressure test unit and a leakage test unit, characterized in that: the stator part is composed of a pump body (43), a rear pump cover (6), the front sealing ring (1), the rear sealing ring (39), the through cylinder (32), the 2# skeleton seal (40), and the 3# skeleton seal (35); the rotor part is composed of the pump shaft (44). ), impeller (3), balance hole plate (10), balance hole (36), 1# skeleton seal (42), key (37), round nut (34); the pressure test unit is composed of 1# pressure taking Hole (9), 1# pressure measuring chamber (8), 1# pressure measuring conduit (16), 1# pair of wire joints (17), 1# pressure hose (19), 1# ball valve (21), 2# Pressure taking hole (12), 2# pressure measuring chamber (11), 2# pressure measuring conduit (31), 2# pair of wire joints (18), 2# pressure hose (20), 2# ball valve (25), The surge tank (24), the exhaust valve (22), and the positive and negative pressure gauges (23) are composed; It is composed of meter (29) and balance cavity (14). 2 . The device for calibrating the flow coefficient of the balance hole of a centrifugal pump impeller according to claim 1 , characterized in that: in the stator component, the through cylinder ( 32 ) is fixedly connected to the rear through the B group bolt and nut assembly ( 33 ). 3 . On the right side of the pump cover (6), there is a certain gap between the left end face of the through cylinder (32) and the right side wall of the impeller rear cover plate (4). The inner side is machined from left to right along the axial direction with two levels of inner steps, and the inner step surface is perpendicular to the central axis; the 2# skeleton seal (40) is positioned and installed on the right side of the first-level inner step surface of the through cylinder (32) through the stopper. On the inner wall of the through cylinder (32), the left end face of the 2# skeleton seal (40) is flush with the inner step surface of the first stage of the through cylinder (32); the 3# skeleton seal (35) is positioned and installed on the through cylinder ( 32) On the inner wall of the through cylinder (32) on the right side of the inner step surface of the second stage, the left end face of the 3# skeleton seal (35) is flush with the second inner step surface of the through cylinder (32). 3. The device for calibrating the flow coefficient of the balance hole of a centrifugal pump impeller according to claim 1, characterized in that: in the rotor part, the impeller (3) is fixedly installed on the pump shaft (44) through a key (37). , a reserved hole (2) for the impeller is provided at a position with a smaller radius on the rear cover plate (4) of the impeller, and the balance hole plate (10) is positioned and installed on the pump shaft (44) and the key through the stop on the hub of the impeller (3). On (37), starting from the right end face of the balance orifice plate (10), two outer steps are machined on the outside of the balance orifice plate (10) from right to left in the axial direction, and the outer step surface is perpendicular to the central axis; the balance hole is The left outer surface of the disc (10) fits with the sealing lip of the 2# skeleton seal (40), the right outer surface of the balance orifice disc (10) fits with the sealing lip of the 3# skeleton seal (35), and the balance orifice disc (10 ) There is a gap between the first step surface on the right side and the left end of the 3# skeleton seal (35); the impeller (3) and the balance hole disc (10) are axially fixed on the pump shaft (44) through the round nut (34); balance The hole (36) is horizontally opened on the balance hole plate (10) in the axial direction; the 1# skeleton seal (42) is installed on the inner side of the impeller seal ring (41), and the left end face of the 1# skeleton seal (42) is connected to the rear of the impeller. The cover plate (4) is fitted, and the sealing lip of the 1# skeleton seal (42) fits with the outer surface of the left side of the through cylinder (32). 4. A device for calibrating flow coefficient of centrifugal pump impeller balance holes according to claim 1, characterized in that: in the pressure test unit, the 1# pressure taking hole (9) is vertically opened along the radial and axial directions In the reverse L-shaped hole on the left of the balance orifice plate (10), the number of 1# pressure taking holes (9) is equal to the number of balance holes (36). The impeller rear cover plate (4), the balance orifice plate (10), The 2# skeleton seal (40), the first step surface of the through cylinder (32), the inner wall of the through cylinder (32), and the 1# skeleton seal (42) enclose the 1# pressure measuring cavity (8); 1# pressure measuring The conduit (16) is set on the transparent cylinder (32), the left end of the 1# pressure measuring conduit (16) is communicated with the 1# pressure measuring chamber (8), and the right end of the 1# pressure measuring conduit (16) passes through the 1# pair of wire joints (17) communicates with the left end of the 1# pressure hose (19), the 2# pressure taking hole (12) is a short hole vertically opened in the right part of the balance hole plate (10) in the radial direction, and the 2# pressure taking hole (12) The number is equal to the number of the balance holes (36), the outer surface of the balance orifice plate (10), the second-stage outer step surface of the balance orifice plate (10), the 3# skeleton seal (35), the second through-tube (32) The step surface, the inner wall of the through cylinder (32) and the 2# skeleton seal (40) enclose the 2# pressure measuring cavity (11); the 2# pressure measuring conduit (31) is horizontally opened on the through cylinder (32) along the axial direction , the left end of the 2# pressure measuring conduit (31) is connected with the 2# pressure measuring chamber (11), and the right end of the 2# pressure measuring conduit (31) is connected with the 2# pressure hose (20) through the 2# pair of wire joints (18) Connect on the left. 5. The device for calibrating the flow coefficient of a centrifugal pump impeller balance hole according to claim 1, characterized in that: in the leakage test unit, the outer surface of the through cylinder (32), the flange of the through cylinder (32) The left side surface of the disc, the inner wall surface of the right cylinder of the rear pump cover (6), the right end face of the rear sealing ring (39), the impeller sealing ring (41) and the 1# skeleton seal (42) enclose the drainage cavity (13) ; Two water diversion pipes (47) are fixedly installed on both sides of the cylinder on the right side of the rear pump cover (6) along the radial direction. The flange on the left side of the water diversion pipe (47) is butted with the flanges on both sides of the cylinder on the right side of the rear pump cover (6), and is fixedly connected with the E group bolt and nut assembly (45). The flanges are butted with the flanges on both sides of the return chamber (27), and are firmly connected with the bolt and nut assemblies (46) of group F. The left flange of the return chamber (27) is butted with the right flange of the electromagnetic flowmeter (29). , and use the bolt and nut assembly (28) of group D to connect together. The left flange of the electromagnetic flowmeter (29) is butted with the right flange of the through cylinder (32), and is fixedly connected with the bolt and nut assembly (30) of group C. , the inner wall surface of the through cylinder (32), the 3# skeleton seal (35), the balance hole plate (10), the round nut (34), and the right end face of the pump shaft (44) enclose the balance chamber (14); the balance hole ( 36) Connect the balance chamber (14) with the inlet of the impeller (3).

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