CN101629583A - Methods for calculating and thickening profile of impeller vane of axial flow pump - Google Patents

Abstract

The invention relates to methods for calculating the profile of an axial flow type vane and thickening the aerofoil thickness, which are mainly used under a working condition with high revolution ratio, namely, a working condition with large flow rate and low lift. The invention is characterized in that the profile of a stream line of the working face of the vane is calculated according to the geometrical relationship of the mounting angles of the inlets and the outlets of the stream lines of different stream surfaces and a circular arc type profile when the axial flow type impeller is designed, and then different stream lines of the working face of the vane are thickened according to the change rule of the aerofoil thickness. By practice and application, the geometric parameter of the impeller designed by using the invention meets the requirements of the lift and the flow rate of the design working condition of a water pump, and the impeller has high efficiency, good vapor erosion performance and simple design process and has certain popularization value.

Description

A kind of profile of impeller vane of axial flow pump calculates and the thickening method

Technical field

The present invention relates to determining and aerofoil profile thickening method of a kind of axial-flow pump aial flow impeller working surface molded lines.Determine working surface molded lines on the different stream interfaces of blade according to the streamline characteristic, and according to profile thickness Changing Pattern thickening molded lines.This method especially can be used for the big flow low lift impeller hydraulic model of design.

Background technique

The lift method is the method that is mainly used to design axial flow pump impeller vane at present.The lift method is the method that is used for designing axial flow pump impeller vane the earliest.The supposition of lift method design blade is: the impeller blade number seldom, the fluid winding flow in the impeller blade grid approaches around the streaming of single wing, thereby the influence of aerofoil profile interaction opposing connection properties of flow is little in the impeller blade grid.According to this supposition, can regard each aerofoil profile in the aial flow impeller blade grid as isolated, and be applied in the test result of carrying out single aerofoil profile in the wind-tunnel and design blade.Because above-mentioned supposition has certain approximation, in design, need convection cell to stream leaf grating and revise for this reason with the difference of independent wing, therefore cause uncertainty.And the existing aviation power aerofoil profile of the direct reference of lift method, import position plumpness is not suitable for being used to come flow path direction to change the blade of little axial flow pump.What patented technology 96119277 patent No. aial flow impellers that have had earlier proposed a kind of compact structure is used to stir axial-flow blower, does not have to propose to be fit to the vane airfoil profile that axial-flow pump impeller flows.Only determine the flow model and the flow parameter of axial flow impeller machine in the design method of 200710079869 application number axial flow impeller machines and the blade, do not had inventing type line computation method and blade thickening mode.

Summary of the invention

In order to overcome in the axial-flow pump design process deficiency with reference to aviation Airfoil Design impeller profile, the axial-flow pump aial flow impeller among the present invention is imported and exported laying angle and is determined according to Euler's equation, also can revise it according to different flowing laws.

Technological scheme of the present invention is:

A kind of molded lines of axial flow pump impeller vane calculates and the thickening method, wherein

1) molded lines calculates:

Determine the radius R of circular arc molded lines according to the geometrical relationship of the import laying angle of different stream interfaces upper reaches line and outlet laying angle and circular arc streamline,

$R=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A2009100325600007H1.png,A2009100325600008H1.png"\; state="\{\{state\}\}">l</figure-callout>}}{2\sin \frac{\mathrm{\&theta;}}{2}}=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A2009100325600007H1.png,A2009100325600008H1.png"\; state="\{\{state\}\}">l</figure-callout>}}{2\sin \left(\frac{{\mathrm{\&beta;}}_2-{\mathrm{\&beta;}}_1}{2}\right)}=\frac{H}{\cos {\mathrm{\&beta;}}_1-\cos {\mathrm{\&beta;}}_2}$

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; H-aerofoil profile height; L-string of a musical instrument length

2) molded lines thickening:

According to the varied in thickness rule of following formula aerofoil profile, respectively each bar molded lines of working surface is thickeied to the back side from working surface.

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.

The present invention is according to the import laying angle β of the different stream interfaces of blade ₁With outlet laying angle β ₂, determine wing chord angle β _L, evaluation work face molded lines radius R, and thicken rule according to aerofoil profile and thicken, be a kind of design method of innovation, simple and practical.The spoon of blade of design is smooth, and this design method not only can satisfy the requirement of design parameter by facts have proved, and the efficient height, good combination property.

Description of drawings

The present invention is further described below in conjunction with drawings and Examples.

Fig. 1 is the calculating schematic representation of the inventive method design axial-flow pump impeller working surface molded lines.

Fig. 2 is the schematic representation of working surface molded lines thickening rule.

Fig. 3 is molded lines and thickening figure as a result among the embodiment.

Among the figure, β ₁, β ₂-molded lines is into and out of bicker; γ-molded lines the angle of curvature; θ-molded lines central angle; H-aerofoil profile camber; L-string of a musical instrument length; δ-profile thickness; δ _Max-maximum profile thickness; T-pitch, R-circular arc molded lines radius, β _L-aerofoil profile laying angle, x-aerofoil profile suction surface arrive the distance of inlet side.

Embodiment

The specific speed of embodiment's aial flow impeller is 1000, impeller diameter D ₂=300, n=1450r/min.Detailed process can be with reference to table 1, and stream interface generally divides 5～7, divides 5 in this enforcement, is branch stream interface 1,2,3,4,5, and the stream interface spacing equates, as Fig. 1.Calculate the import flow angle β ' of streamline on each stream interface ₁, be respectively 15.37 °, 18.28 °, 22.39 °, 28.06 °, 36.86 °, select angle of attack Δ β ₁, Δ β ₁The scope of selecting for use be (0 °～3 °), determine inlet blade angle β ₁=β ' ₁+ Δ β ₁, be respectively 16.97 °, 19.48 °, 23.19 °, 28.46 °, 36.86 °.Calculate each streamline outlet flow angle β ' ₂, be respectively 17.18 °, 21.11 °, 27.27 °, 37.51 °, 58.54 °.Consider factor affecting such as the limited number of blade, Δ β ₂The scope of selecting for use be (0 °～3 °), every streamline adds the angle of attack and determines 1 ° in the present embodiment, then blade outlet angle β ₂=β ' ₂+ Δ β ₂, be respectively 18.18 °, 22.11 °, 28.27 °, 38.51 °, 59.54 °.Select the string of a musical instrument length l of different streamlines, be respectively 188.50mm, 176.24mm, 160.54mm, 139.96mm, 116.87mm.Calculating formula according to working surface molded lines radius R $R=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A2009100325600007H1.png,A2009100325600008H1.png"\; state="\{\{state\}\}">l</figure-callout>}}{2\sin \frac{\mathrm{\&theta;}}{2}}=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A2009100325600007H1.png,A2009100325600008H1.png"\; state="\{\{state\}\}">l</figure-callout>}}{2\sin \left(\frac{{\mathrm{\&beta;}}_2-{\mathrm{\&beta;}}_1}{2}\right)}$ Calculate circular arc line radius R, result of calculation is respectively 8943mm, 3831mm, 1811mm, 799mm, 297mm.Import laying angle β according to working surface ₁With outlet laying angle β ₂Draw the aerofoil profile unfolded drawing with the molded lines radius, as shown in Figure 2.

The aial flow impeller computational process of table 1 specific speed 1000

The aerofoil profile maximum ga(u)ge of wheel hub by formula ${\mathrm{\&delta;}}_{\max }=(0.012~0.015)D_2\sqrt{H}$ Estimating, is 300 axial-flow pump model usually for diameter, and blade outer edge side maximum ga(u)ge is got 5mm, and the hub side maximum ga(u)ge is got 14mm, and the thickness from the wheel hub to the wheel rim changes according to linear rule.Determine that aerofoil profile 5,4,3,2,1 maximum ga(u)ge of blade from the wheel rim to the wheel hub is respectively 5.2mm, 6.9mm, 8.6mm, 10.3mm, 12mm is according to formula δ/δ _Max=2.1437 (x/l) ³-6.9947 (x/l) ²+ 4.8445 (x/l)+0.052 calculate profile thickness thickening rule such as following table 2:

The varied in thickness rule of table 2 aerofoil profile

According to profile thickness thickening rule, the working surface molded lines is thickeied, as shown in Figure 3.Do plane figure, the axis projection of blade at last, as shown in Figure 4.

This impeller is by test, and optimum efficiency point is as following table 3.

The impeller optimum efficiency point parameter list of table 3 specific speed 1000

Claims (1)

1, a kind of molded lines of axial flow pump impeller vane calculates and the thickening method, it is characterized in that,

1) molded lines calculates:

Determine the radius R of circular arc molded lines according to the geometrical relationship of the import laying angle of different stream interfaces upper reaches line and outlet laying angle and circular arc streamline, the formula of circular arc molded lines radius R is $R=\frac{l}{2\sin \frac{\mathrm{\&theta;}}{2}}=\frac{l}{2\sin \left(\frac{{\mathrm{\&beta;}}_2-{\mathrm{\&beta;}}_1}{2}\right)}$

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) molded lines thickening:

Calculate profile thickness according to profile thickness in the following formula with the different Changing Pattern of extension position, each bar molded lines of working surface thickeied to the back side from working surface,

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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