CN103486023B

CN103486023B - Screw pump and screw rod

Info

Publication number: CN103486023B
Application number: CN201310289262.XA
Authority: CN
Inventors: 毛海峰; 唐倩; 张元勋; 江振伟
Original assignee: CHONGQING DEHENG TECHNOLOGY Co Ltd
Current assignee: CHONGQING DEHENG TECHNOLOGY Co Ltd
Priority date: 2013-07-10
Filing date: 2013-07-10
Publication date: 2015-10-28
Anticipated expiration: 2033-07-10
Also published as: CN103486023A

Abstract

The invention discloses a kind of screw pump and screw rod, wherein in the inlet end face of screw rod, be provided with streamlined structure, by this streamlined structure, the axial velocity that liquid flows into screw rod confined space can be increased, thus strengthen the suction stream ability of screw pump, improve its volumetric efficiency.

Description

Screw pump and screw

Technical Field

The invention relates to a screw pump and a screw.

Background

In the screw pump, when the main screw and the auxiliary screw are meshed to rotate, a closed space with constantly changed space volume is formed, when the closed space at the inlet end is constantly enlarged, a low-pressure area is formed at the inlet, so that liquid in a pump cavity obtains an initial speed in the axial direction of the screw due to the action of pressure difference, the liquid originally in a laminar flow motion state on the end face of the screw flows into the inlet of the closed space of the screw, and the continuity of conveying the liquid by the screw is achieved.

Through analysis, the flow suction capacity of the screw pump is determined by the liquid level speed at the inlet of the closed space caused by pressure difference, and when the axial speed of liquid flowing into the closed space of the screw is increased, the flow suction capacity of the pump is improved, so that the improvement of the axial speed of the liquid flowing into the closed space of the screw is an effective means for increasing the flow suction capacity of the screw pump.

Disclosure of Invention

In view of this, the invention provides a screw pump and a screw, which can improve the flow suction capacity and the volumetric efficiency of the screw pump.

The invention provides a screw pump, comprising: the screw rod, be provided with streamlined structure on the import terminal surface of screw rod.

Further, the streamline structures correspond to different radiuses R_iThe coordinates of the cross section satisfy the following constraint conditions:

<math> <mrow> <msub> <mi>θ</mi> <mi>bc</mi> </msub> <mo>=</mo> <mi>arccos</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <mn>2</mn> <msubsup> <mi>R</mi> <mi>i</mi> <mn>2</mn> </msubsup> <mo>-</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mrow> <mi>b</mi> <mn>0</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>x</mi> <mrow> <mi>c</mi> <mn>0</mn> </mrow> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>-</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>y</mi> <mrow> <mi>b</mi> <mn>0</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>y</mi> <mrow> <mi>c</mi> <mn>0</mn> </mrow> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> <mrow> <mn>2</mn> <msubsup> <mi>R</mi> <mi>i</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>,</mo> </mrow> </math>

wherein x is_a0、y_a0Is the coordinates of the starting point of the tooth-shaped end surface of the screw; x is the number of_c、y_cThe coordinates of corresponding points on the converted streamline end surface are obtained; theta_abThe included angle between any point and the initial point in the process of converting the linear-circular arc coordinates of the point; theta_bcThe included angle is generated by converting the point in the arc-tooth-shaped coordinate; l_ABThe length between any point and the starting point in the linear-circular arc coordinate is shown; r_iThe radius corresponding to any point is long; x is the number of_b0、y_b0Is the coordinate of the starting point in the arc-tooth coordinate; x is the number of_c0、y_c0The coordinates of the point on the screw tooth profile corresponding to the starting point.

The invention also provides a screw, and the inlet end face of the screw is provided with a streamline structure.

Further, the streamline structure corresponds to different radiuses R_iThe coordinates of the cross section satisfy the following constraint conditions:

The invention has the beneficial effects that:

in the embodiment of the invention, the inlet end face of the screw is provided with the flat end face with the streamline structure, so that liquid cannot keep a parallel running state after passing through the non-planar streamline structure and can generate a speed along the axial direction of the screw, and when the liquid at the inlet end face of the screw enters the closed space, the liquid not only has the axial speed generated under the action of pressure difference, but also has the axial component speed generated under the action of streaming motion, so that the speed of the liquid entering the closed space is greatly improved, the flow suction capacity and the volume efficiency of the screw pump are increased, and particularly the conveying capacity of the high-flow high-pressure high-end screw pump can be ensured.

Drawings

The invention is further described below with reference to the following figures and examples:

fig. 1 is a schematic structural diagram of an embodiment of a screw provided by the present invention.

Fig. 2 is a top view of fig. 1.

Fig. 3 is a schematic structural view of an embodiment of a streamline structure.

Fig. 4 is a schematic view of the structure in the direction of a-a in fig. 3.

FIG. 5 is a diagram of a cylindrical bypass model.

Fig. 6- (a) is a perspective view of an optimized rear port end face streamlined body.

Fig. 6- (b) is a projection view of fig. 6- (a) after the straight-line-circular-arc coordinate transformation.

Fig. 6- (c) is a projection view of fig. 6- (b) after the arc-tooth coordinate transformation.

Fig. 7 is a schematic diagram of the straight-line-circular-arc coordinate conversion.

Fig. 8 is a schematic diagram of arc-tooth coordinate conversion.

Detailed Description

Fig. 1 is a schematic structural view of an embodiment of a screw according to the present invention, fig. 2 is a top view of fig. 1, fig. 3 is a schematic structural view of an embodiment of a streamline structure, and fig. 4 is a schematic structural view of a direction a-a in fig. 3, in which reference numeral 1 denotes a "rotor" and reference numeral "2" denotes a streamline structure.

The screw pump of the embodiment of the invention mainly improves the inlet end face structure of the screw, the inlet end face of the conventional screw is of a flat structure, the inlet end face of the screw of the embodiment of the invention is provided with the streamline structure 2, so that when the screw rotates, the streamline structure and the screw are integrated, the streamline structure rotates along with the screw, the situation at the moment can be equivalently converted into a static state of the screw according to the relativity of the motion, the liquid at the inlet end of the screw rotates around the axis of the screw, the liquid can not keep a parallel motion state after passing through a non-planar streamline object but flows along the surface of a streamline body according to the object streaming principle, after the fluid bypasses the streamline body, a velocity component along the axial direction of the screw is generated at the inlet of a closed space, and when the liquid at the inlet end face of the screw enters the closed space, the axial speed generated by the pressure difference effect and the axial component speed generated by the circumfluence movement are provided, so that the speed of the liquid entering the closed space is improved compared with the prior art, and the flow suction capacity of the pump is improved.

Specifically, the conversion formula of the flow suction capacity eta of the screw pump is as follows

Wherein Q is the end face inlet flow; Δ V is the volume change of the enclosed space; q_pThe flow rate of the liquid entering the closed space of the pump depends on the pressure difference action only; q_vIs the flow rate entering the pump enclosure due to the axial velocity. Q_v＝u₀S，u₀The component of the velocity obtained by the liquid after the liquid flows around through the streamline structure in the axial direction; s is the area of the end face when the screw closed space is formed, and u is the area when no streamline object exists₀0. Therefore, when there is no streamline structure,when the streamline structure is provided, the air conditioner,is obvious eta_before<η_afterTherefore, after the streamline structure is added, the flow suction capacity of the screw pump is remarkably improved.

Further, the following specifically analyzes an optimized form of the streamline structure.

In order to make the fluid at the inlet end face of the screw have an initial y-direction component velocity when entering the closed space formed by the meshing area of the pump, the separation point of the boundary layer at the inlet end face of the screw is positioned at the defluidizing side of the cylindrical symmetry line, and the gradient of the fluid at the point when the fluid is separated from the separation point can be minimized, namely, the included angle theta between the velocity direction of the fluid at the separation point and the vertical direction is_sepAt a minimum, as shown in fig. 5.

Obtaining an optimization model of the flow line type structure of the inlet end face of the screw pump according to the relation between the cylindrical streaming flow line and the boundary layer separation:

<math> <mrow> <mi>min</mi> <mo>:</mo> <msub> <mi>θ</mi> <mi>sep</mi> </msub> <mo>=</mo> <mi>arctan</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <mn>2</mn> <mi>x</mi> <mrow> <mo>(</mo> <mi>Ψ</mi> <mo>-</mo> <mi>Uxy</mi> <mo>)</mo> </mrow> </mrow> <mrow> <mi>U</mi> <mrow> <mo>(</mo> <msup> <mi>x</mi> <mn>2</mn> </msup> <mo>+</mo> <mn>3</mn> <msup> <mi>y</mi> <mn>2</mn> </msup> <mo>-</mo> <msup> <mi>R</mi> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>-</mo> <mn>2</mn> <mi>Ψy</mi> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>-</mo> <mfrac> <mi>π</mi> <mn>2</mn> </mfrac> </mrow> </math>

<math> <mrow> <mi>s</mi> <mo>.</mo> <mi>t</mi> <mo>.</mo> <mo>:</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <mi>Ψ</mi> <mo>=</mo> <mi>Uy</mi> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <mfrac> <msup> <mi>R</mi> <mn>2</mn> </msup> <mrow> <msup> <mi>x</mi> <mn>2</mn> </msup> <mo>+</mo> <msup> <mi>y</mi> <mn>2</mn> </msup> </mrow> </mfrac> <mo>)</mo> </mrow> </mtd> </mtr> <mtr> <mtd> <mi>tan</mi> <msub> <mi>α</mi> <mi>sep</mi> </msub> <mo>=</mo> <mfrac> <mrow> <mn>2</mn> <mi>x</mi> <mrow> <mo>(</mo> <mi>Ψ</mi> <mo>-</mo> <mi>Uy</mi> <mo>)</mo> </mrow> </mrow> <mrow> <mi>U</mi> <mrow> <mo>(</mo> <msup> <mi>x</mi> <mn>2</mn> </msup> <mo>+</mo> <mn>3</mn> <msup> <mi>y</mi> <mn>2</mn> </msup> <mo>-</mo> <msup> <mi>R</mi> <mn>2</mn> </msup> <mi>y</mi> <mo>-</mo> <msup> <mi>R</mi> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>-</mo> <mn>2</mn> <mi>Ψy</mi> </mrow> </mfrac> </mtd> </mtr> <mtr> <mtd> <mfrac> <mrow> <mo>&PartialD;</mo> <msub> <mi>p</mi> <mi>t</mi> </msub> </mrow> <mrow> <mo>&PartialD;</mo> <mi>x</mi> </mrow> </mfrac> <mo>=</mo> <mo><</mo> <mn>0</mn> </mtd> </mtr> <mtr> <mtd> <msub> <mi>θ</mi> <mi>t</mi> </msub> <mo>=</mo> <mi>π</mi> <mo>-</mo> <msub> <mi>α</mi> <mi>sep</mi> </msub> </mtd> </mtr> <mtr> <mtd> <mi>Ψ</mi> <mo>></mo> <mn>0</mn> <mo>,</mo> <mi>U</mi> <mo>></mo> <mn>0</mn> <mo>,</mo> <mi>x</mi> <mo>></mo> <mn>0</mn> <mo>,</mo> <mi>y</mi> <mo>></mo> <mn>0</mn> </mtd> </mtr> <mtr> <mtd> <msup> <mi>x</mi> <mn>2</mn> </msup> <mo>+</mo> <msup> <mi>y</mi> <mn>2</mn> </msup> <mo>></mo> <msup> <mi>R</mi> <mn>2</mn> </msup> </mtd> </mtr> </mtable> </mfenced> </mrow> </math>

wherein, theta_sepIs the included angle between the fluid speed direction and the vertical direction at the separation point; x and y are coordinate values at the separation point; u is the linear velocity of the screw end face corresponding to different radiuses; r is the radius of the root circle; alpha is alpha_sepIs the angle between the opposite direction of the fluid velocity and the horizontal at the separation point.

The optimized rear entry end surface streamline type volume projection views calculated by the same method for the geometrical parameters of the tooth-shaped end surface of the screw pump are shown in fig. 6- (a) to 6- (c).

And correspondingly converting the streamline body shown in the figure 6- (a) to the screw tooth-shaped end surface as shown in the figure 6- (c) by combining the screw tooth-shaped parameters and applying a coordinate conversion relation in order to obtain the streamline body on the screw tooth-shaped inlet end surface by combining the screw tooth-shaped streamline body layout. As shown in fig. 7 and 8, the following coordinate conversion relationship is required.

(1) And (5) transforming straight line-circular arc coordinates.

Wherein the rotating coordinate relationship is as follows:

wherein x is_a0、y_a0Is the coordinates of the starting point of the tooth-shaped end surface of the screw; theta_abThe included angle between any point and the initial point in the process of converting the linear-circular arc coordinates of the point; l_ABThe length between any point and the starting point in the linear-circular arc coordinate is shown; x is the number of_a、y_aThe coordinate of any point on the straight line before coordinate conversion; x is the number of_b、y_bThe coordinates of any point on the straight line after coordinate conversion.

(2) Arc-tooth coordinate transformation

<math> <mrow> <msub> <mi>θ</mi> <mi>bc</mi> </msub> <mo>=</mo> <mi>arccos</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <mn>2</mn> <msubsup> <mi>R</mi> <mi>i</mi> <mn>2</mn> </msubsup> <mo>-</mo> <msubsup> <mi>l</mi> <mi>AD</mi> <mn>2</mn> </msubsup> </mrow> <mrow> <mn>2</mn> <msubsup> <mi>R</mi> <mi>i</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>)</mo> </mrow> </mrow> </math>

Wherein

l_{AD} = \sqrt{{({x_{b 0} - x_{vc 0}})}^{2} + {(y_{b 0} - y_{c 0})}^{2}},

Substitute for human

<math> <mrow> <msub> <mi>θ</mi> <mi>bc</mi> </msub> <mo>=</mo> <mi>arccos</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <mn>2</mn> <msubsup> <mi>R</mi> <mi>i</mi> <mn>2</mn> </msubsup> <mo>-</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mrow> <mi>b</mi> <mn>0</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>x</mi> <mrow> <mi>c</mi> <mn>0</mn> </mrow> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>-</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>y</mi> <mrow> <mi>b</mi> <mn>0</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>y</mi> <mrow> <mi>c</mi> <mn>0</mn> </mrow> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> <mrow> <mn>2</mn> <msubsup> <mi>R</mi> <mi>i</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>)</mo> </mrow> </mrow> </math>

The coordinate conversion relation from the arc segment AC to the arc segment DE is as follows:

finally, the coordinate transformation relationship of fig. 6- (a) to fig. 6- (c) can be obtained, written in matrix form:

wherein,

<math> <mrow> <mmultiscripts> <mrow> <msub> <mi>θ</mi> <mi>ab</mi> </msub> <mo>=</mo> <mfrac> <msub> <mi>l</mi> <mi>AB</mi> </msub> <msub> <mi>R</mi> <mi>i</mi> </msub> </mfrac> <mo>=</mo> <mfrac> <mrow> <msub> <mi>x</mi> <mi>a</mi> </msub> <mo>-</mo> <msub> <mi>x</mi> <mrow> <mi>a</mi> <mn>0</mn> </mrow> </msub> </mrow> <msub> <mi>R</mi> <mi>i</mi> </msub> </mfrac> <mo>,</mo> </mrow> </mmultiscripts> <msub> <mi>θ</mi> <mi>bc</mi> </msub> <mo>=</mo> <mi>arccos</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <msubsup> <mrow> <mn>2</mn> <mi>R</mi> </mrow> <mi>i</mi> <mn>2</mn> </msubsup> <mo>-</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mrow> <mi>b</mi> <mn>0</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>x</mi> <mrow> <mi>c</mi> <mn>0</mn> </mrow> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>-</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>y</mi> <mrow> <mi>b</mi> <mn>0</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>y</mi> <mrow> <mi>c</mi> <mn>0</mn> </mrow> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> <mrow> <mn>2</mn> <msubsup> <mi>R</mi> <mi>i</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>.</mo> </mrow> </math>

x_c、y_cthe coordinates of corresponding points on the converted streamline end surface are obtained; theta_bcThe included angle is generated by converting the point in the arc-tooth-shaped coordinate; r_iThe radius corresponding to any point is long; x is the number of_b0、y_b0Is the coordinate of the starting point in the arc-tooth coordinate; x is the number of_c0、y_c0The coordinates of the point on the screw tooth profile corresponding to the starting point.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. A screw pump, comprising: the screw rod, its characterized in that: and a streamline structure is arranged on the inlet end face of the screw rod.

2. The screw pump of claim 1, wherein: the streamline structures correspond to different radiuses R_iThe coordinates of the cross section satisfy the following constraint conditions:

<math> <mrow> <msub> <mi>θ</mi> <mi>bc</mi> </msub> <mo>=</mo> <mi>arccos</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <msubsup> <mrow> <mn>2</mn> <mi>ar</mi> </mrow> <mi>i</mi> <mn>2</mn> </msubsup> <mo>-</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mrow> <mi>b</mi> <mn>0</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>x</mi> <mrow> <mi>c</mi> <mn>0</mn> </mrow> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>-</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>y</mi> <mrow> <mi>b</mi> <mn>0</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>y</mi> <mrow> <mi>c</mi> <mn>0</mn> </mrow> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> <msubsup> <mrow> <mn>2</mn> <mi>R</mi> </mrow> <mi>i</mi> <mn>2</mn> </msubsup> </mfrac> <mo>)</mo> </mrow> <mo>,</mo> </mrow> </math>

3. A screw, characterized in that: and a streamline structure is arranged on the inlet end face of the screw rod.

4. The screw of claim 3, wherein: the streamline structure corresponds to different radiuses R_iThe coordinates of the cross section satisfy the following constraint conditions: