CN201539437U - A high-efficiency axial flow pump impeller - Google Patents

Abstract

The utility model is an axial-flow impeller mainly used in the working condition of high specific revolution number, that is, the working condition of large flow and low lift. It is characterized in that the axial-flow impeller calculates the profile of the streamline of the blade working surface from the geometric relationship between the angle of the inlet and outlet of the streamline and the arc shape of the different flow surfaces, and then calculates the profile of the blade working surface according to the airfoil thickness change formula. Different streamlines are thickened. Through practical application, the geometric parameters of the axial-flow impeller of the utility model not only meet the head and flow requirements of the design working condition of the water pump, but also have high efficiency, good cavitation performance, simple design process, and certain popularization value.

Description

A high-efficiency axial flow pump impeller

technical field

The invention relates to a main part of a non-variable displacement pump. The profile line of the working surface of the blade of the axial flow impeller is determined by the streamline characteristics, and the profile line is thickened according to the change rule of the airfoil thickness. The impeller can be used in the occasion of large flow and low head.

Background technique

At present, the impeller of axial flow pump is mainly designed by the lift method. The assumption of blade design by lift method is that the number of impeller blades is small, and the fluid flow around the impeller cascade is close to the flow around a single wing, so the airfoil interaction in the impeller cascade has little influence on the flow characteristics. According to this assumption, each airfoil in the axial-flow impeller cascade is regarded as isolated, and the test results of a single airfoil in the wind tunnel are used to design the blades. Since the above assumptions are approximate to a certain extent, it is necessary to correct the difference between the fluid flowing around the cascade and the individual airfoil, which leads to uncertainty in the performance of the impeller. Moreover, most of the airfoils of the impellers of axial flow pumps refer to the existing aerodynamic airfoils, and the inlet part is thick, which is not suitable for the blades of axial flow water pumps whose incoming flow direction does not change much.

The prior invention patent technology 96119277 Patent No. Axial flow impeller proposes a compact axial flow impeller for stirring, which provides a large discharge with a small torque, but the impeller is only suitable for storage Dispersion of droplets or particles in low to medium concentration liquids in liquid tanks. Utility Model Patent No. ZL02204291.1 proposes an axial-flow impeller with a curved tip. The original straight line perpendicular to the axis of the impeller is bent at an appropriate angle at the tip to form a curved surface, and the width of the tip rotates along the impeller. The opposite direction of the flow increases, so that the blade can use the energy contained in the fluid before it leaves the blade tip, so as to achieve the purpose of improving the energy conversion efficiency. In the patent application No. 200580024657.0 of the enhanced-flow axial-flow impeller, the contour section of the blade is determined by aerodynamics. The above-mentioned patented technologies have proposed the structure and shape characteristics of the impellers of axial flow pumps in different occasions, but none of them have proposed the determination method of the airfoil characteristics and blade profiles of different circumferential sections of the axial flow impellers. These existing patented technologies cannot meet the performance requirements of the axial flow pump impellers in irrigation projects, chemical processes and other projects in my country.

Contents of the invention

In order to overcome the deficiencies of the existing axial-flow pump impellers based on aviation airfoil design, the blades of the axial-flow impeller in the present invention are calculated according to the placement angles of the streamline inlet and outlet on different flow surfaces to obtain the profile of the working surface. And thicken according to the airfoil thickening rule.

Technical scheme of the present invention is:

A high-efficiency axial flow pump impeller, the radius R of the arc-shaped line on its blade is determined by the following formula:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="l"\; filenames="DEST\_PATH\_HSB00000022367300021.png,DEST\_PATH\_HSB00000022367300042.png"\; state="\{\{state\}\}">l</figure-callout></span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\frac{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="l"\; filenames="DEST\_PATH\_HSB00000022367300021.png,DEST\_PATH\_HSB00000022367300042.png"\; state="\{\{state\}\}">l</figure-callout></span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}$

In the formula, R-the radius of the working surface profile; β ₁ -the placement angle of the streamline inlet; β ₂ -the placement angle of the streamline exit; θ-the center angle of the profile line; l-the length of the chord.

The maximum thickness of airfoil a, b, c, d, e from the rim to the hub is 5.2mm, 6.9mm, 8.6mm, 10.3mm, 12mm respectively. According to the change law of the thickness of the airfoil in the following formula, the five lines of the working face are thickened from the back of the working face.

δ/δ _max = 2.1437(x/l) ³ -6.9947(x/l) ² +4.8445(x/l)+0.052

In the formula, l-chord length; δ-airfoil thickness; δ _max -the maximum airfoil thickness, X-the distance from the airfoil suction surface to the inlet edge.

The determination of the profile line of the blade and the thickening rule of the blade are the unique design of the impeller of the present invention, which is simple and practical. Practice has proved that the impeller can not only meet the requirements of design parameters, but also has high efficiency and good comprehensive performance.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is an axial flow pump impeller of the present invention.

Fig. 2 is an airfoil diagram of the flow surfaces of the impellers a, b, c, d and e of the axial flow pump of the present invention.

Fig. 3 is a flow surface position diagram of the impellers a, b, c, d and e of the axial flow pump of the present invention.

Figure 4 is a schematic diagram of the relationship between the geometric parameters of the arc profile of the airfoil working face.

Fig. 5 is a schematic diagram of the profile line thickening law of the airfoil working face.

Fig. 6 is a plane projection view of the blade in the embodiment.

Fig. 7 is an axial projection view of the blade in the embodiment.

Fig. 8 is an A-direction view of the blade in the embodiment.

Fig. 9 is an airfoil diagram of the a-flow surface of the blade in the embodiment.

Fig. 10 is an airfoil diagram of the flow surface of the blade b in the embodiment.

Fig. 11 is an airfoil diagram of the flow surface of the blade c in the embodiment.

Fig. 12 is an airfoil diagram of the blade d flow surface in the embodiment.

Fig. 13 is an airfoil diagram of the e-flow surface of the blade in the embodiment.

β ₁ , β ₂ -inlet and outlet angles of the type line; γ-type line curvature angle; θ-type line central angle;

h-airfoil camber; l-chord length; δ _- airfoil thickness; δ _max -maximum airfoil thickness; The distance from the airfoil suction side to the inlet side.

Detailed ways

The specific speed of the axial flow impeller is 1000, the impeller diameter D ₂ =300, n=1450r/min, as shown in FIG. 1 . The specific implementation process can refer to Table 1. Generally, there are 5 to 7 flow surfaces. In this implementation, the number of blades is 3, and each blade is divided into 5 flow surfaces a, b, c, d, e, and the distance between the flow surfaces is equal, as shown in Figure 1 and Figure 3. Calculate the inlet liquid flow angle β ₁ ′ of the streamline on each flow surface, which are 15.37°, 18.28°, 22.39°, 28.06°, 36.86° respectively, and choose the angle of attack Δβ ₁ , and the selection range of Δβ ₁ is (0°～3 °), determine the blade inlet angle β ₁ = β ₁ ′+Δβ ₁ , which are 16.97°, 19.48°, 23.19°, 28.46°, 36.86° respectively. Calculate the liquid flow angle β ₂ ′ at the outlet of each streamline, which are 17.18°, 21.11°, 27.27°, 37.51°, 58.54° respectively. Considering the influence of factors such as the limited number of blades, the selection range of _Δβ2 is (0°～3°). In this embodiment, each streamline plus the angle of attack is determined to be 1°, then the blade outlet angle _β2 = _β2 ′+ _Δβ2 , are 18.18°, 22.11°, 28.27°, 38.51°, 59.54°, respectively. Select the string length l of different streamlines, which are 188.50mm, 176.24mm, 160.54mm, 139.96mm, 116.87mm respectively. According to the calculation formula of the radius R of the working surface profile $R=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DEST\_PATH\_HSB00000022367300021.png,DEST\_PATH\_HSB00000022367300042.png"\; state="\{\{state\}\}">l</figure-callout>}}{2\sin \frac{\mathrm{\&theta;}}{2}}=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DEST\_PATH\_HSB00000022367300021.png,DEST\_PATH\_HSB00000022367300042.png"\; state="\{\{state\}\}">l</figure-callout>}}{2\sin \left(\frac{{\mathrm{\&beta;}}_2-{\mathrm{\&beta;}}_1}{2}\right)}$ Calculate the radius R of the arc-shaped line, and the calculation results are 8943mm, 3831mm, 1811mm, 799mm, and 297mm, as shown in Figure 2. According to the inlet placement angle β ₁ and outlet placement angle β ₂ of the working face and the profile radius, draw the airfoil expansion diagram, as shown in Figure 4.

Table 1 Calculation process of axial flow impeller with specific speed of 1000

The maximum thickness of the airfoil at the hub is according to the formula ${\mathrm{\&delta;}}_{\max }=(0.012~0.015){\mathrm{D.}}_2\sqrt{h}$ It is estimated that for an axial flow pump model with a diameter of 300, the maximum thickness of the outer edge of the blade is 5mm, and the maximum thickness of the hub side is 14mm, and the thickness from the hub to the rim changes linearly. Determine the maximum thickness of the airfoil 5, 4, 3, 2, and 1 of the blade from the rim to the hub to be 5.2mm, 6.9mm, 8.6mm, 10.3mm, and 12mm respectively, according to the formula δ/δ _max = 2.1437(x/l) ³ -6.9947(x/l) ² +4.8445(x/l)+0.052 Calculate the thickening law of the airfoil thickness as shown in Table 2:

Table 2 Thickness Variation Law of Airfoil

According to the law of airfoil thickness thickening, the working surface profile line is thickened, and the blade inlet and outlet are rounded, as shown in Figure 5. Finally, make the planar projection of the blade (Fig. 6), the axial projection (Fig. 7) and the A-direction view (Fig. 8), and make the airfoils of the flow surfaces a, b, c, d and e respectively, see respectively Figure 9, Figure 10, Figure 11, Figure 12 and Figure 13.

Claims (2)

1. an efficient axial-flow pump impeller is characterized in that, the radius R of circular arc molded lines on the blade of axial-flow pump impeller is to be determined by following formula: $R=\frac{l}{2\sin \frac{\mathrm{\&theta;}}{2}}=\frac{l}{2\sin \left(\frac{{\mathrm{\&beta;}}_2-{\mathrm{\&beta;}}_1}{2}\right)}$

R-working surface molded lines radius in the formula;

β ₁-streamline import laying angle;

β ₂-streamline outlet laying angle;

θ-molded lines central angle;

L-string of a musical instrument length.

2. axial-flow pump impeller as claimed in claim 1 is characterized in that: blade has a, b, c, d, five molded lines of e from the wheel rim to the wheel hub, the maximum ga(u)ge of a, b, c, d, e is respectively 5.2mm, 6.9mm, 8.6mm, 10.3mm, 12mm; Article five, molded lines thickens to the back side from working surface, and thickness meets following formula with the different Changing Pattern of extension position:

δ/δ _max＝2.1437(x/l) ³-6.9947(x/l) ²+4.8445(x/l)+0.052

L-string of a musical instrument length in the formula; δ-profile thickness; δ _Max-maximum profile thickness, x-aerofoil profile suction surface is to the distance of inlet side.

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