CN109185227A - A kind of solid-liquid two-phase flow centrifugal pump cut water design method - Google Patents

Abstract

The invention belongs to the field of fluid machinery, and relates to a design method for separating tongues of a solid-liquid two-phase flow centrifugal pump. The new elastic tongue structure consists of an elastic part and a rigid part; the elastic part consists of a working part and a fixed part; the working part is elastically deformed by the extrusion of solid particles, thereby increasing the gap between the tongue and the impeller, and finally making the large Solid particles of particle size pass safely without affecting the normal operation and energy performance of the pump. The fixing part fixes the elastic part by interference fit with the rigid part. The invention has simple structure and easy operation, can effectively increase the diameter of the particles that can pass through the tongue, and does not affect the energy performance of the pump, can ensure that there is no blockage in the pump when conveying solid-liquid two-phase flow, and continuously stabilize the solid-liquid for the pump. Two-phase flow delivery provides great protection.

Description

A design method for separating tongues of a solid-liquid two-phase flow centrifugal pump

technical field

The invention belongs to the field of fluid machinery, and particularly relates to a design method for separating tongues of a solid-liquid two-phase flow centrifugal pump.

Background technique

In order to ensure that the hydraulic performance of the centrifugal pump meets the requirements, the gap between the tongue and the impeller is generally designed to be as small as possible. This makes it easy for the centrifugal pump to block the gap between the impeller and the tongue or damage the impeller because the gap between the separation tongue and the impeller is too small when the centrifugal pump is transporting solid-liquid two-phase flow. In order to prevent blockage in the pump or damage to the impeller, it is necessary to increase the gap between the tongue and the impeller, which will lead to a significant decrease in the hydraulic performance of the pump. Therefore, it is necessary to invent a structure design for the separation tongue of a solid-liquid two-phase flow centrifugal pump, so that it can not only ensure the hydraulic performance of the pump, but also prevent the solid particles from being blocked or damaged when passing through the gap between the impeller and the separation tongue.

To this end, a solid-liquid two-phase flow centrifugal pump separator that can widen the gap is designed. The separator is divided into two parts: an elastic part and a rigid part. The elastic part is divided into a working part and a fixed part. The elastic part is made of elastic material. , the rigid part is made of rigid material; the elastic part is fixed in the groove of the rigid part through the interference fit between the fixed part and the rigid part; when the particle size of the pump conveyed is larger than the gap between the impeller and the tongue, the working part of the elastic part is elastic Deformation, widening the gap between the tongue and the impeller, allowing the particles to pass safely without damaging the blades or clogging.

So far, there is no patent publication on the design method of the separation tongue of the solid-liquid two-phase flow centrifugal pump, and the present invention provides a design method of the separation tongue of the solid-liquid two-phase flow centrifugal pump.

SUMMARY OF THE INVENTION

The invention provides a design method for separating tongues of a solid-liquid two-phase flow centrifugal pump.

The present invention is achieved through the following technical solutions: a method for designing a diaphragm for a solid-liquid two-phase flow centrifugal pump, comprising an elastic material, a rigid material, an elastic convex groove and a rigid groove; the elastic material and the rigid material pass through corresponding The concave-convex groove is inserted and fixed by interference fit; in order to prolong the working life of the elastic material, the corners of the groove and the convex groove are rounded; the closed space formed between the elastic groove and the rigid convex groove can effectively prevent the Give way.

The specific working process of the invention is as follows: when the centrifugal pump is transporting solid-liquid two-phase flow, when larger particles pass through the gap between the impeller and the separator tongue, the gap is enlarged by squeezing the elastic separator tongue, so that the particles can safely pass through the gap. Avoid pump blockage and vane damage. After the particles pass through safely, the elastic diaphragm returns to its original state to ensure that the hydraulic performance of the pump remains stable.

In the above solution, the design length L of the working part is determined according to the required deformation amount w of the working part.

In the above scheme, the design parameters of the working part are based on the design length L of the working part, and are determined by the design parameters of the volute of the centrifugal pump.

In the above solution, the design parameters of the elastic groove and the rigid convex groove are determined according to the design length L of the working part.

Beneficial effects: the present invention is simple in structure and easy to operate, and the gap between the tongue and the impeller can be increased by elastic deformation of the elastic material, so that the centrifugal pump can still maintain the normal operation of the impeller and no blockage when transporting larger solid particles; The invention provides a guarantee for the centrifugal pump to safely transport the solid-liquid two-phase flow.

Description of drawings

Fig. 1 is the axial sectional view of the separation tongue of the solid-liquid two-phase flow centrifugal pump

Fig. 2 is the sectional view of the separating tongue of the solid-liquid two-phase flow centrifugal pump

Figure 3 is a diagram of the rigid groove of the separation tongue of the solid-liquid two-phase flow centrifugal pump

Figure 4 is a diagram of the elastic bump of the separating tongue of the solid-liquid two-phase flow centrifugal pump

Figure 5 is a schematic diagram of the deformation of the separation tongue of the solid-liquid two-phase flow centrifugal pump

In the figure: 1 rigid part 2 elastic part 3 rigid groove 4 cross-shaped rigid convex groove 5 elastic protrusion 6 cross-shaped elastic groove

Detailed ways

Example:

A solid-liquid two-phase flow centrifugal pump separation tongue structure comprises a rigid part and an elastic part, the rigid part adopts rigid material, and the elastic part adopts elastic material. The elastic part is further divided into a working part and a fixed part. The design parameters of centrifugal pump are flow rate Q=40m ³ /h, head H=8.0m, rotational speed n=2800r/min, number of blades Z=5, blade outlet angle β ₂ =30°, blade outlet axial surface speed V _m2 =6.28 m/s, the peripheral speed of the blade outlet u ₂ =20.5m/s, the outer diameter of the impeller D ₂ =140mm, the width of the impeller outlet b = 18mm, the thickness of the blade inlet δ ₃ =3mm, the flow angle of the impeller outlet _α 3 =13°, Diameter of the base circle of the tongue _D3 = 142mm, the upper width of the tongue section b ₁ = 27mm, the lower width of the tongue section b ₂ = 25mm, the height of the tongue section h = 4.5mm, the radius of the arc on both sides of the tongue section R =6mm, the experimental design flow rate is 1.0Q _d , and the experimental pumping particle size is d=16mm. The present invention will be further described below in conjunction with the accompanying drawings:

1. Two material requirements for the design of the separation tongue of the solid-liquid two-phase flow centrifugal pump:

(1) The rigid material is cast iron, that is, the casting material of the pump body.

(2) The elastic material is rubber.

The ultimate stress of rubber is σ _rubber = 75Mpa

The theoretical head of the solid-liquid two-phase flow centrifugal pump is

in,

but

Among them, the theoretical lift is H _t , the peripheral velocity at the blade outlet is u ₂ =20.5m/s, the slip coefficient is σ, the blade outlet axial velocity is V _m2 =6.28m/s, and the blade outlet angle is β ₂ =30° , the number of blades is Z=5.

Therefore, the internal stress of the _pump is σpump=ρ×g×H _t =1000×9.8×6.67=65366Pa≈0.07Mpa,

In order to ensure the normal operation of the centrifugal pump, the maximum stress in the pump is taken as [σ] _pump = 1.2 × σ _pump = 1.2 × 0.07 = 0.084Mpa,

At this time, σ _rubber >> [σ] _pump ,

Therefore, the selection of rubber as the elastic material can meet the design requirements of the solid-liquid two-phase flow centrifugal pump.

2. Determine the maximum elastic deformation amount w of the working part according to the maximum particle size d of the pumped particles.

(1) The theoretical maximum deformation w ₁ of the elastic material 2 is determined according to the maximum particle size d of the pumped particles, which satisfies the formula.

w ₁ =D ₂ /2+dD ₃ /2

According to the design parameters of centrifugal pump, take D ₂ =140mm, D ₃ =142mm, d = 16mm, get w ₁ =15mm.

(2) The maximum elastic deformation w of the working part needs to satisfy w≥1.2w ₁ , so w≥18mm. Take w=18mm.

3. Determine the shape design of the working part according to the design length L of the working part.

(1) Determine the design length L of the working part according to the maximum deformation w required by the working part.

L ³ Aτ=3wEI

Among them, the cross-sectional area of the tongue is A, the shear stress is τ, the elastic modulus E=7.84MPa, the shear modulus G=1.95MPa, the moment of inertia is I, α is the central angle of the tongue The width b ₁ =27mm, the lower width b ₂ of the tongue section is 25mm, the height of the tongue section is h = 4.5mm, and the radius of the arc on both sides of the tongue section is R = 6mm.

The simultaneous formula is L=15.88mm, and L is rounded to obtain L=16mm.

(2) Taking the design length L of the working part as the design reference parameter, determine the remaining design parameters of the working part, including the inlet width b ₃ of the volute, the placement angle of the tongue The helix angle α ₀ of the tongue is calculated as follows:

Among them, b ₌ 18mm, L=16mm, therefore, take b3 as 30mm;

in, Flow rate Q=40m ³ /h, head H=8.0m, rotational speed n=2800r/min, working part design length L=16mm;

According to the table below, take the placement angle of the tongue

Wherein, the outlet width of the volute b ₃ =30mm, is the displacement coefficient, the blade inlet thickness δ ₃ = 3mm, the number of blades Z = 5, the base circle diameter of the tongue is D ₃ = 142mm, the impeller outlet flow angle α ₃ = 13°, the blade outlet peripheral speed u ₂ = 20.5m/s , the theoretical lift H _t =6.67m;

4. The rigid part 1 and the elastic part 2 are fixed by elastic pressing.

(1) The size of the rigid groove 3 of the rigid part 1 is determined according to the design length L. Among them, the specific design parameters of the rigid groove 3, the length is a ₁ =0.7L, that is, a ₁ =11.2mm, rounded a ₁ =11mm, and the depth is c ₁ =0.6L, that is, c ₁ =9.6mm, rounded is c ₁ =10mm;

The specific design parameters of the cross-shaped rigid convex groove 4 on the four sides of the rigid groove 3 of the rigid part 1 are a ₁ =11mm in length, c ₁ =10mm in depth, and h ₂ =0.1L in height, that is, h ₂ =1.6mm , the rounding is h ₂ =2mm, the width is b ₄ =0.1L, that is, b ₄ =1.6mm, and the rounding is b ₄ =2mm.

(2) The size of the elastic bump 5 of the elastic portion 2 is determined according to the design length L. Wherein, the length is a ₃ =0.75L, that is, a ₃ =12mm, and the depth is c ₂ =0.5L, that is, c ₂ =8mm;

Among them, the specific design parameters of the four-sided cross-shaped elastic groove 6 of the elastic bump 5 of the elastic part 2 are a ₃ =11mm in length, c ₂ =8mm in depth, and h ₄ =0.08L in height, that is, h ₄ =1.28mm, The rounding is h ₄ =1mm, the width is b ₄ =0.08L, that is, b ₄ =1.28 mm, and the rounding is b ₄ =1 mm.

(3) The elastic pressure generated by the cross-shaped elastic groove 6 and the cross-shaped rigid protrusion 4 through the interference fit, and the elastic pressure generated by the elastic protrusion 5 and the rigid groove 3 through the interference fit, so that the elastic material 2 is fixed to the rigid Inside the rigid groove 3 of the material 1. In order to prolong the service life of the elastic material 2 , the corners of the rigid groove 3 , the cross-shaped rigid protrusions 4 , the cross-shaped elastic protrusion grooves 6 and the elastic protrusions 5 are rounded.

The working process of the present invention is as follows:

When the centrifugal pump is transporting solid-liquid two-phase flow, some solid particles do not leave the volute through the pump outlet pipe, but continue to rotate with the impeller for the next round. When the solid particles are just located in the gap between the impeller outlet and the separation tongue When in position, the elastic material 2 is elastically deformed by the solid particles to the water outlet end, increasing the gap between the impeller and the separator, so that the solid particles can pass through safely without causing pump blockage or blade damage. The deformation diagram is as attached. As shown in Figure 5;

The invention can effectively ensure no blockage in the pipeline and zero damage to the impeller when the pump is conveying solid-liquid two-phase flow, and significantly improve the service life and operation stability of the centrifugal pump; The solid-liquid two-phase flow transportation provides a feasible design method for the separation tongue of the solid-liquid two-phase flow centrifugal pump.

Claims (5)

1. a solid-liquid two-phase flow centrifugal pump separating tongue design method is characterized in that comprising the following concrete steps: (1) The structure of the solid-liquid two-phase flow centrifugal pump includes a rigid part 1 and an elastic part 2, the rigid part 1 is made of rigid material, and the elastic part 2 is made of elastic material; the elastic part is the working part and the fixed part; (2) The maximum deformation variable w of the working part is determined according to the maximum particle size d conveyed by the solid-liquid two-phase flow centrifugal pump; (3) The shape design of the working part is determined according to the design length L of the working part; (4) According to the material properties of the rigid part 1 and the elastic part 2 of the solid-liquid two-phase flow centrifugal pump, a suitable connection method is designed. 2. A method for designing a solid-liquid two-phase flow centrifugal pump separator tongue according to claim 1, characterized in that: the material selection requirements of the rigid part 1 and the elastic part 2; (1) The rigid material is the material used in the rigid part 1, and the casting material of the pump body is used; (2) The elastic material is the material used in the elastic part 2; the ultimate bearing stress of the elastic material is greater than the theoretical lift H _t , The theoretical head H _t is determined according to the formula: Among them, the theoretical lift is H _t , the peripheral velocity at the blade outlet is u ₂ , the slip coefficient is σ, the blade outlet axial velocity is V _m2 , the blade outlet angle is β ₂ , and the number of blades is Z; (3) The elastic part 2 is divided into a working part and a fixed part. The fixed part and the rigid part are clamped and fixed. The working part increases the gap between the impeller and the tongue through elastic deformation to ensure the normal operation of the solid-liquid two-phase flow centrifugal pump. 3. a kind of solid-liquid two-phase flow centrifugal pump separation tongue design method according to claim 1, is characterized in that: described working part maximum deformation variable w value steps are as follows: (1) Calculate the theoretical maximum deformation variable w ₁ of the working part according to the formula; w ₁ =D ₂ /2+dD ₃ /2 (d>D ₃ /2-D ₂ /2) Among them, the theoretical maximum elastic deformation amount is w ₁ , the outer diameter of the impeller is D ₂ , and the diameter of the base circle of the tongue is D ₃ ; (2) In order to leave a sufficient elastic deformation safety margin for the working part, the value of the maximum deformation variable w must be no less than 1.2 times the theoretical maximum elastic deformation value w ₁ , that is, w≥1.2w ₁ . 4. a kind of solid-liquid two-phase flow centrifugal pump design method according to claim 1, is characterized in that: the shape design of described working part is determined by the design length L of working part, and concrete steps are as follows: (1) Determine the design length L of the working part according to the required deformation value w of the working part, and the specific calculation formula is as follows: L ³ Aτ=3wEI Among them, the cross-sectional area of the tongue is A, the shear stress is τ, the elastic modulus is E, the shear modulus is G, the moment of inertia is I, α is the central angle of the tongue section, and b ₁ is the upper width of the tongue section , b ₂ is the lower width of the tongue section, h is the height of the tongue section, R is the radius of the arc on both sides of the tongue section; (2) Taking the design length L of the working part as the design reference parameter, determine the remaining design parameters of the working part, including the inlet width b ₃ of the volute, the placement angle of the tongue The tongue separation helix angle α ₀ , the value method is as follows: Determine the placement angle of the tongue according to the value of _ns +lgL range of values; When _35≤ns +lgL≤62, When _62≤ns +lgL≤143, When 143≤n _s +lgL≤214, When _213≤ns +lgL≤372, Among them, b is the width of the impeller outlet, is the displacement coefficient, δ ₃ is the blade inlet thickness, and α ₃ is the liquid flow angle at the impeller outlet. 5. The method for designing a solid-liquid two-phase flow centrifugal pump separator tongue according to claim 1, wherein the connection mode of the rigid part 1 and the elastic part 2 is based on the material properties and the design length L of the working part. decision, the specific steps are as follows: (1) For the rigid part 1, cut a square with a length of a ₁ =0.7L on its surface and a rigid groove 3 with a depth of c ₁ =0.6L; add a length of a ₁ to the four sides of the rigid groove 3, A cross-shaped rigid protrusion 4 with a depth of c ₁ , a width of b ₄ =0.1L, and a height of h ₂ =0.1L; (2) The elastic part 2, corresponding to the part of the elastic part 2 installed into the rigid groove 3, is designed with an elastic bump 5, the length is a ₃ =0.75L square, and the depth is c ₂ =0.5L; A cross-shaped elastic groove 6 with a length of a ₃ , a depth of c ₂ , a height of h ₄ =0.08L, and a width of b ₄ =0.08L is added on four sides; the elastic bump 5 is the fixing part of the elastic part 2 ; (3) Both the rigid groove 3 and the cross-shaped rigid protrusion 4 are on the rigid part 1; the cross-shaped elastic protrusion 6 is located on the fixed part of the elastic part 2; the cross-shaped elastic groove 6 and the cross-shaped rigid protrusion 4 pass through the The elastic pressure generated by the interference fit, and the elastic pressure generated by the elastic bump 5 and the rigid groove 3 through the interference fit, make the elastic part 2 fixed in the rigid groove 3 of the rigid part 1; in order to prolong the service life of the elastic part 2, The corners of the rigid groove 3 , the cross-shaped rigid protrusion 4 , the cross-shaped elastic protrusion 6 and the elastic protrusion 5 are rounded.