Design method of impeller of hydraulic turbine pump

Abstract

The invention relates to a design method of a hydraulic turbine pump impeller. The method comprises the following steps that (1) the impeller is designed through hydraulic power; (2) blade thickening design; (3) an impeller outlet is widened, and the turbine working condition b2 'is larger than the width b3 of a guide vane inlet; and (4) an impeller machining drawing is drawn. The step (2) comprises the specific steps that (201) the impeller blades are thickened, so that the impeller blades are of a wing-shaped structure with a thin inlet, a thick middle and a thin outlet; a fillet design is adopted at the outlet edge; (202) according to the impeller structure designed in the step (201), a CFD analysis model is adopted, and a water pump working condition model and a turbine working condition model are analyzed and corrected; and (203) drawing a cutting drawing and a processing drawing of the impeller. According to the design of the impeller, on the basis of an optimized hydraulic model, the design concepts of a water turbine and a water pump are fused, the contradiction between the guide vane inlet width and the impeller outlet width is solved, the guide vane inlet width and the impeller outlet width are both considered, and efficiency improvement is achieved to the maximum extent.

Description

Technical Field

[0001] The present invention relates to a design method, in particular to a design method for a hydraulic turbine pump impeller which systematically analyzes the internal structure and hydraulics of a pump and improves them to form a systematic design method, thereby improving the overall efficiency of the unit. Background Art

[0002] In today's energy-scarce world, hydraulic turbine pumps, which have both the delivery capacity of water pumps and the recovery capacity of water turbines, should have become the darling of the times. However, since it is neither a water turbine nor a water pump, there is no complete reference for its design method. If the pump is designed according to the pump method under the working condition of the pump, the turbine working condition will not have the high efficiency of the water turbine; if the turbine is designed according to the design method of the water turbine, the water pump working condition will not have the high efficiency of the water pump. As a product of energy utilization and recycling, it will lose its own meaning if it is not supported by high efficiency. People are constantly exploring and pursuing higher efficiency and the meaning of existence. There are currently three common hydraulic turbine pump design methods on the market:

[0003] The first is to use a common water pump directly as a hydraulic turbine pump through slight structural adjustments;

[0004] The second is a new design of the entire pump, which optimizes key components based on pump efficiency analysis software and methods;

[0005] The third is to design using the design method of key parts of turbines.

[0006] The above three types of water pumps have their own advantages and disadvantages, as follows:

[0007] The first type directly uses an ordinary water pump and uses it as a hydraulic turbine pump through slight adjustments to the structure. Its biggest advantage is that it is low cost and can be quickly produced and put into production. It can also be used as a water pump. At the same time, its disadvantage is also obvious, that is, the efficiency is obviously low, far from meeting the efficiency standards of turbines of the same level.

[0008] The second new design of the entire pump should be the best method to maximize the overall quality of the hydraulic turbine pump. However, since it is based on water pump efficiency analysis software and methods, it only optimizes key components, and the water flow direction of the hydraulic turbine pump is opposite to the direction of water pump operation. As an energy recovery, this software method is not very accurate at present. The efficiency of the entire pump is generally higher than the first method, and of course the cost is greatly increased.

[0009] The third method uses the design method of the key parts of the turbine. This method can improve the efficiency of the hydraulic turbine. The hydraulic turbine pump designed by this method has a complex structure. More precisely, it should be called a turbine. The design method of the turbine is generally based on the design method of large equipment, and the hydraulic turbine pump is generally based on a small energy recovery device. Generally, the power is not too large. The current recovery power is within 500KW, while the production-type turbine equipment is generally above 1000KW. And the efficiency of the hydraulic turbine equipment designed by this design method is far less than that of the separately designed pump if it is operated as a water pump. Summary of the invention

[0010] In view of the above problems, the main purpose of the present invention is to provide a design method for a hydraulic turbine pump impeller by systematically analyzing the internal structure and hydraulics of the pump and improving them to form a systematic design method, thereby improving the overall efficiency of the unit.

[0011] The present invention solves the above technical problems through the following scheme: a design method for a hydraulic turbine pump impeller, the design method for a hydraulic turbine pump impeller comprising the following steps:

[0012] Step (1), the impeller is hydraulically designed;

[0013] Step (2), blade thickening design;

[0014] Step (3), widening the impeller outlet so that the turbine operating condition b2'> the guide vane inlet width b3;

[0015] Step (4), draw the impeller processing drawing.

[0016] In a specific implementation example of the present invention, the specific steps of step (2) include:

[0017] Step (201), thickening the impeller blades so that the impeller blades are thin at the inlet, thick in the middle, and thin at the outlet in a wing-shaped structure; and a rounded corner design is adopted at the outlet edge;

[0018] Step (202), according to the impeller structure designed in step (201), using the CFD analysis model, analyzing the models of the pump working condition and the turbine working condition, and correcting them;

[0019] Step (203), draw the impeller cutting diagram and processing diagram.

[0020] In a specific implementation example of the present invention, the specific steps of step (3) include:

[0021] Step (301), widening the impeller outlet, and b2'>b3, the impeller outlet is first chamfered by 30-45 degrees, the chamfer depth is 5-8% of the impeller diameter, and between 3-8 mm;

[0022] Step (302), the two ends of the chamfer adopt rounded corners R3-R6 to smoothly transition with the front and rear cover plates;

[0023] Step (303), again using the CFD analysis model to analyze the hydraulic performance of the pump operating condition and the turbine operating condition;

[0024] Step (304): if the result is not satisfactory, repeat steps 1 to 3.

[0025] In a specific implementation example of the present invention, the specific steps of step (4) include: drawing the final impeller processing drawing according to the impeller cutting drawing and chamfering requirements.

[0026] In a specific implementation example of the present invention, an oblique angle is made along the axial direction at the outer diameter of the impeller near the outer circle.

[0027] In a specific implementation example of the present invention, the bevel angle is controlled at 30° to 45°, the bevel depth is 5 to 8% of the outer diameter of the impeller, and finally both ends of the bevel are supplemented with rounded transitions.

[0028] The positive progress of the present invention is that compared with the common similar technologies, the design method of the hydraulic turbine pump impeller provided by the present invention is based on the water research and structural analysis of the conventional turbine pump, and then improved. The design of the impeller is based on the optimized hydraulic model, integrating the design concepts of the turbine and the water pump, solving the contradiction between the guide vane inlet width and the impeller outlet width, achieving a balance between the two, and maximizing efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the impeller outlet width and guide vane inlet width designed for a conventional water pump.

[0030] Figure 2 This is a schematic diagram of the structure of the optimized design of the flow passage of the impeller outlet in the present invention.

[0031] Figure 3 Design flow diagram for conventional water pumps.

[0032] Figure 4 The figure shows the water flow in the working condition of the water pump after the application of the present invention.

[0033] Figure 5 Schematic diagram of water flow for turbine operation using conventional water pump design method (front view).

[0034] Figure 6 Schematic diagram of water flow for turbine operation using conventional water pump design method (right view).

[0035] Figure 7 Schematic diagram of water flow in turbine operating condition in the present invention (front view).

[0036] Figure 8 Schematic diagram of water flow in turbine operating condition in the present invention (right view).

[0037] Fig. 9 It is a schematic diagram of the impeller blades in the present invention.

[0038] The following are the names corresponding to the labels in the present invention:

[0039] Figure 2 and Figure 3 middle:

[0040] Impeller 1, impeller sealing ring 2, middle section sealing ring 3, suction box body 4, guide vane 5, middle section 6, guide vane sealing ring 7, hub sealing ring 8, shaft 9. DETAILED DESCRIPTION

[0041] Preferred embodiments of the present invention are given below in conjunction with the accompanying drawings to illustrate the technical solutions of the present invention in detail.

[0042] Figure 1 Design the impeller outlet width and guide vane inlet width structure diagram for conventional water pumps, such as Figure 1 As shown: According to the design concept of the water pump: the inlet width b3 of the guide vane 5 is wider than the outlet width b2 of the impeller 1, and the relationship is b3 = b2 + (2 ~ 5mm), while the turbine pump design hopes that b2>b3, and when b2>b3 is met, the efficiency of the turbine working condition can be improved. However, it is impossible for the conventional water pump design to have b2>b3, and such a design does not meet the water pump design requirements, which greatly reduces the efficiency of the water pump.

[0043] The present invention proposes a design method for a hydraulic turbine pump impeller, and the design method for a hydraulic turbine pump impeller comprises the following steps:

[0044] Step (1), the impeller is hydraulically designed;

[0045] Step (2), blade thickening design;

[0046] Step (3), widening the impeller outlet so that the turbine operating condition b2'> the guide vane inlet width b3;

[0047] Step (4), draw the impeller processing drawing.

[0048] In step (1), the impeller is hydraulically designed according to the velocity coefficient method or the similarity conversion method. Here, the similarity conversion method is used:

[0049] The specific steps of the above step (1) include:

[0050] 101. Select the model based on the parameters;

[0051] 102. Model modification;

[0052] 103. Calculate similarity conversion coefficients;

[0053] 104. Draw the new impeller working surface.

[0054] The specific steps of the above step (1) are currently common technologies and will not be described in detail here.

[0055] The specific steps of the above step (2) include:

[0056] 201. The new impeller blades are thickened (wing-shaped structure with thin inlet, thick in the middle and thin outlet); the impeller blades in the present invention are first thin from the inlet to the outlet, then thick, and finally thinned, and a rounded corner design is adopted at the outlet edge.

[0057] 202. According to the newly designed impeller structure, the CFD analysis model (pump condition and turbine condition) is adopted and modified;

[0058] 203. Draw the impeller cutting and processing drawings.

[0059] The specific steps of the above step (3) include:

[0060] 301. The impeller outlet is widened and modified to b2'>b3. The impeller outlet is chamfered at 30-45°. The chamfer depth is 5-8% of the impeller diameter and between 3-8 mm.

[0061] 302. The two ends of the chamfer adopt rounded corners R3 to R6 to smoothly transition with the front and rear cover plates;

[0062] 303. CFD is used again to analyze the hydraulic performance of the model (pump condition and turbine condition);

[0063] 304. If the result is not satisfactory, repeat steps 1 to 3.

[0064] The specific steps of the above step (4) include: drawing the final impeller processing drawing according to the impeller cutting drawing and chamfering requirements.

[0065] The present invention optimizes the design of the flow passage at the impeller outlet so that b2'>b3, as shown in FIG. Figure 2 As shown, b2' here can be understood as turbine operating condition b2, but as water pump operating condition b2, no substantial change occurs, so it will not affect the efficiency of the water pump operating condition.

[0066] The present invention makes an oblique angle along the axial direction at the outer diameter of the impeller near the outer circle, the degree of the oblique angle is controlled to be 30° to 45°, and the depth of the oblique angle is 5 to 8% of the outer diameter of the impeller (see Figure 2 ) (the degree and depth of the bevel angle are both smaller according to the larger impeller diameter, and vice versa), and finally, fillet transition is added at both ends of the bevel (see Figure 2 A).

[0067] The present invention optimizes the design of the flow passage at the impeller outlet so that b2'>b3, as shown in FIG. Figure 2 As shown, b2' here can be understood as turbine operating condition b2, but as water pump operating condition b2, no substantial change occurs, so it will not affect the efficiency of the water pump operating condition.

[0068] In order to illustrate that b2' can be considered as the turbine operating condition, the present invention combines Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , specifically explains how the present invention achieves improvement in turbine efficiency.

[0069] Figure 3 This is a schematic diagram of the water flow in a conventional water pump design. The water flow is indicated by pink arrows ( Figure 3 The arrow at M in the figure shows the direction of water flow. After the water flows through the impeller to do work, most of it enters the guide vane 5 and then enters the next stage to continue to do work. Some of the water does not do useful work in this process, and as a form of energy loss, Figure 3 Indicated by red arrows ( Figure 3 The arrow at N in the figure represents the direction of water flow, which is mainly concentrated in the vortex flow formed between the impeller 1 and the suction box 4, and the vortex flow formed between the impeller and the guide vane. These are all part of the energy loss (these two parts are often called mechanical losses). This part of the energy loss is generally reduced by improving the finish of the impeller cover. Another part of the loss comes from the gap backflow between the guide vane sealing ring and the hub sealing ring, and the gap backflow between the middle sealing ring 7 and the impeller sealing ring 2 (these two parts are often called volume loss). This part of the energy loss is generally reduced by increasing the gap width and increasing the gap length.

[0070] Figure 4 This is a schematic diagram of the water flow in the water pump working condition after the invention is applied. Figure 4 It is not difficult to see that the water flow state remains basically unchanged, and Figure 3 Keeping consistent, the losses in each part also remain unchanged, so it can be concluded that this invention will not affect the efficiency of the original water pump, that is, the working efficiency of the water pump remains unchanged.

[0071] Figure 5 , Figure 6 This is a schematic diagram of the water flow in turbine operation under conventional water pump design method. The water flow is indicated by pink arrows ( Figure 5 and 6 The arrow at P in the figure shows the direction of water flow. Figure 3 , Figure 4 The water flow direction of the pump working condition is just the opposite. The water flow loss includes all the losses of the pump working condition, and the impact loss from the guide vane to the impeller outlet is added. Figure 5 and 6 The red arrow indicates ( Figure 5 and 6 According to the research, this part of impact loss is between 4% and 8%. In other words, reducing this part of loss is equivalent to increasing efficiency by 4% to 8%. Figure 5 For the main view, Figure 6 It is the right view.

[0072] Figure 7 , Figure 8 This is the schematic diagram of the turbine operating condition designed for this method. The water flow is indicated by pink arrows ( Figure 7 and 8 The arrow at S in the figure shows the direction of water flow. Figure 5 , Figure 6 Compared with the lack of guide vanes and impact losses at the impeller outlet, this design method increases efficiency by 4% to 8% over conventional design methods.

[0073] Fig. 9 is a schematic diagram of the impeller blades in the present invention, Fig. 9 In the process, the impeller blades are first thin, then thick, and finally thinned from the inlet to the outlet, and a rounded corner design is adopted at the outlet edge.

[0074] The present invention utilizes a design method to reduce losses and thus improve efficiency, and mainly includes: an impeller, guide vanes, a middle section, etc. As the core component of the pump, the impeller converts the mechanical energy transmitted from the prime mover through the shaft into the kinetic energy of the fluid in pump operation, and converts the pressure energy of the fluid into mechanical kinetic energy in turbine operation, and then transmits it to the traction device through the shaft. Its energy efficiency will determine the energy efficiency value of the entire device. The guide vanes and the middle section are also the main components of the multi-stage pump, and they work together to form a complete transition flow channel. Their main function is to convert the kinetic energy of the fluid converted by the impeller into pressure energy in pump operation and transmit it to the next-stage impeller or outlet, and to guide the fluid in turbine operation, and transmit the pressure energy of the fluid to the impeller for conversion, and provide a pre-injection angle for the fluid to better recover energy for the impeller.

[0075] The present invention is based on the water research and structural analysis of conventional turbine pumps, and then improved. The impeller design is based on the optimized hydraulic model, integrating the design concepts of turbine and water pump, solving the contradiction between the guide vane inlet width and the impeller outlet width, achieving a balance between the two, and maximizing efficiency improvement. The specific impeller design method is as follows:

[0076] Make a bevel at the outer diameter of the impeller along the axial direction to the front and rear cover plates. The degree of the bevel is controlled at 30°~45°, and the depth of the bevel is 5~8% of the outer diameter of the impeller (the degree and depth of the bevel are both smaller according to the larger impeller diameter, and larger according to the smaller impeller diameter). Finally, fillet transition is provided at both ends of the bevel.

[0077] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected, and the scope of the present invention to be protected is defined by the attached claims and their equivalents.

Claims

1. A method for designing a hydraulic turbine pump impeller, characterized in that: The design method of the hydraulic turbine pump impeller comprises the following steps: Step (1), the impeller is hydraulically designed; Step (2), blade thickening design; Step (3), widening the impeller outlet so that the turbine operating condition b2'> the guide vane inlet width b3; Step (4), draw the impeller processing drawing.

2. The method for designing a hydraulic turbine pump impeller according to claim 1, characterized in that: The specific steps of step (2) include: Step (201), thickening the impeller blades so that the impeller blades are thin at the inlet, thick in the middle, and thin at the outlet in a wing-shaped structure; and a rounded corner design is adopted at the outlet edge; Step (202), according to the impeller structure designed in step (201), using the CFD analysis model, analyzing the models of the pump working condition and the turbine working condition, and correcting them; Step (203), draw the impeller cutting diagram and processing diagram.

3. The method for designing a hydraulic turbine pump impeller according to claim 1, characterized in that: The specific steps of step (3) include: Step (301), widening the impeller outlet, and b2'>b3, the impeller outlet is first chamfered by 30-45 degrees, the chamfer depth is 5-8% of the impeller diameter, and between 3-8 mm; Step (302), the two ends of the chamfer adopt rounded corners R3-R6 to smoothly transition with the front and rear cover plates; Step (303), again using the CFD analysis model to analyze the hydraulic performance of the pump operating condition and the turbine operating condition; Step (304): if the result is not satisfactory, repeat steps 1 to 3.

4. The method for designing a hydraulic turbine pump impeller according to claim 1, characterized in that: The specific steps of step (4) include: drawing the final impeller processing drawing according to the impeller cutting drawing and chamfering requirements.

5. The method for designing a hydraulic turbine pump impeller according to claim 1, characterized in that: Make an oblique angle along the axial direction at the outer diameter of the impeller near the outer circle.

6. The method for designing a hydraulic turbine pump impeller according to claim 5, characterized in that: The degree of the bevel is controlled at 30° to 45°, and the depth of the bevel is 5 to 8% of the outer diameter of the impeller. Finally, rounded corners are used at both ends of the bevel.

Images