Pump operation, by bending the central part of the impeller inclined leaves the back end of the centrifugal force is greater than the front end of the centrifugal force and back-end liquid flow pressure is greater than the liquid of the front end of the pressure flow, resulting in each leaf compartment produce radially flow, with the impeller to rotate to generate fluid flow rotary motion, in under the action of the pump shell to form spiral flow, liquid repeatedly into the space between the blades get repeated pressure, resulting in high lift characteristics of constant pressure on output and on the reverse of the impeller blades in pump work can be very well balanced axial force and to guarantee the stability of the pump at work. The impeller structure diagram is shown in Figure 9. 1.
Fig. 1 impeller structure
In the impeller material selection, the aviation material of high strength alloy plastic ZL205A aluminum (or aluminum based composite material) to improve the impeller strength and mechanical properties, surface treatment by anodizing treatment to improve the impeller itself, wear resistance, impeller surface, add Tel-fon abrasion resistant coatings, pump body flow passage coating hard alloy and prolong the service life of the pump.
2.2, sealing structure design
Original spiral flow constant pressure pump (Figure 2) of the seal cavity, sealing liquid in a cavity in the structure and isolated from the outside, pump in operation, the mechanical sealing parts will produce a lot of frictional heat. At this time, the sealing cavity of the heat can not be discharged, continuous work sealing liquid in a cavity temperature continued to rise, and then influence the normal work of the sealing system.
Fig. 2 the structure of the original spiral flow constant pressure pump
In addition, original seal cavity has no exhaust system, pump at the start of irrigation, the gas at the upper part of the chamber can not be discharged, pump running. At this time, the seal cavity body formed gas-liquid mixed state, can not be discharged, have serious consequence for sealing system, caused by failure of the sealing ring, directly affect the product life [9]. Under the joint research of the research group members, a new type of sealing system washing structure was developed. The structure utilizes the pressure difference between the end face of the back cover of the pump and the blade of the impeller in the working time, and the circulating flushing of the mechanical seal system, and plays the role of cooling and exhaust.
Structure principle is: in the pump cover face (the location of the impeller diameter 4 / 5) near the high-pressure zone to the outer edge of the inclined hole is opened on the intake hole), angle of 50 degrees, corresponding to a water inlet hole 180 DEG position pump cover face (the location of the impeller diameter 1 / 2) near the edge of the inner hole of the low pressure area in the open slant hole (hole), angle b=14 degrees, additional throttle bushing, inner ring and impeller hub and sleeve with, and the outer end of the pump cover through a screw fixedly connected. During the operation of the pump, pressure difference water through the water inlet hole is introduced, high-pressure water into the sealed cavity, on the mechanical sealing device for flushing, rinsing according to the direction of the water flow through the water outlet downstream to low-pressure area in the vice impeller blade, to recover some of that energy, improve water efficiency, reduce turbulence loss, in the seal cavity is arranged in the lengthened the throttle bushing, with a small gap (gradients) extended to near the hub of the impeller impeller back shroud, increased leakage resistance, reduce the seal cavity quasi high pressure water, the smoothly returned to the Deputy impeller blade low place, the axial to a certain balance effect. The pump back cover structure diagram is shown in figure 3. Improved spiral flow constant pressure pump product structure diagram shown in Figure 9. 4.
Figure 3 pump back cover structure
Figure 4 improved helical flow constant pressure pump product structure
2.3, product trial
Through the improvement of the above structure design and project team successfully developed a new spiral flow constant pressure pump LXB0.8/4012580230 as shown in Figure 5.
Figure 5 improved LXB0.8/40 - 80 - 230 - 125 pump prototype
3, performance test
The improved LXB0.8/4012580230 types of pump in pump test, computer test system of performance test and cavitation tests required NPSH NPSH not more than 3m), the main performance parameters see Table 1 below.
Table 1 improved LXB0.8/4012580230 spiral flow constant pressure pump main performance parameters
3.1, water and working conditions
Water source for the pressure water tank, water quality for room temperature water (water temperature 15 degrees Celsius), the fluid density of 1000kg/m3, fluid viscosity of 1cSt, are clear water medium. Test conditions: atmospheric pressure is 0.102MPa, rated speed 2980r/min.
3.2, the results of the test
The test results are shown in Figure 6, 7 and 4 to 2.
Figure 6 improved LXB0.8/40 - 80 - 230 - 125 helical flow constant pressure pump performance curve
Figure 7 improved LXB0.8/40 - 80 - 230 - 125 - screw flow constant pressure pump cavitation test curve
Table 2 improved LXB0.8/4012580230 spiral flow constant pressure pump performance test results
Constant pressure pump performance test data step table 3 improved LXB 0 8/40 80 125 230 spiral flow
Table 4 improved LXB 0 8/40 80 125 230 spiral flow constant pressure pump cavitation test data
3.2, test results analysis
By the improvement of the LXB0.8/4012580230 spiral flow constant pressure pump performance test results show that, the pump in a certain speed, input power P increases, inlet pressure P1 decreased slowly, and the increase of flow rate Q, the outlet pressure P2 although there is a slight fluctuations, but has remained unchanged.
Cavitation test actual measurement of the cavitation margin NPSH=2.821m, less than the pump allows the NPSH=3m to be in compliance with the design requirements. From the performance curve can also be seen that with the increase of shaft power P, pump efficiency is increased, and the pump head h remained unchanged. The traditional pump efficiency and single stage head are unable to achieve the characteristics of the spiral flow constant pressure pump. Using this constant pressure, the pump can be widely used in fire, agricultural irrigation, mine drainage, military and other important occasions, 11.
4, conclusion
(1) of the constant pressure pump structure is optimized, so that the liquid into the impeller blade by repeatedly, repeatedly after the working liquid, achieve high lift and export constant output liquid, can be applied to fire protection, industrial, agricultural irrigation and desalination and other occasions; (2) the structure of the impeller was designed for optimization, not blocked pumping with solid impurity particles, improve the operation reliability of the pump, improve safety, and can be used for building drainage, drainage and other complex environments; (3) improvement in impeller materials and processing technology, selection of high strength alloy aluminum plastic ZL205A aerospace materials, greatly improve the machining performance and impeller strength, surface by anodic treatment and adding Telfon anti wear various surface treatment coating, coating hard alloy pump runner, enhance the service life of the pump on the pump body (4); Sealing structure to improve the innovation, can reduce the hydraulic axial force and reduce the fault of the bearing, prolong the service life of the pump, improve efficiency.
Use of the spiral flow physics of the outlet pressure constant pressure output, eliminating the need for existing technology in frequency conversion power supply and control system, not only save energy, but also reduce the weight and the volume of the product, because of its noise is lower than the similar centrifugal pump, it is more convenient to use. XB30/15-LXB65 models in this project has developed a series of products, the national fixed fire extinguishing systems and fire-resistant component quality supervision and inspection center of the inspection, products in the flow 15L/S, speed 2980r/min, single-stage lift has reached more than 300m, meet the fire protection, urban high-rise building to the drainage, mine drainage and other water supply and drainage places their needs. The product has been applied for national invention patents, has now been given priority to enter the substantive examination phase (Patent No.: CN201310324786.8).
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Zhu Rongsheng,