CN1181264C - Axial flow pump impeller vane - Google Patents

Abstract

The present invention relates to a novel impeller blade for axial flow pumps. The impeller blade establishes a correct and reasonable flow model and can obtain fundamental data by the flow model and fundamental equations (1), (2), (3) via design calculation. The impeller blade designs a blade outlet end and a blade root part and adopts an impeller blade with a forward-inclining twisted shape. The impeller blade can effectively control annular boundary layer development on surfaces of a shell and a wheel hub and boundary layer separation on a negative pressure surface of the blade, the impeller blade simultaneously reduces end load of the blade and reduces the influence of gap flow, and a shape of the blade can accord with actual flow better.

Description

Axial flow pump impeller vane

Technical field:

The present invention relates to a kind of axial flow pump impeller vane, belong to field of fluid machinery.

Background technique:

Pump is to use one of universal machine the most widely, and power consumption accounts for 25% of the total electric weight in the whole nation, and wherein axial-flow pump occupies sizable ratio again, and in big-and-middle-sized hydraulic engineering and numerous electromechanical irrigation station, major part has all been used the axial-flow pump unit.But the efficient of China's axial-flow pump impeller hydraulic model is lower by 1～3% than external advanced level on the whole, and main cause is not deep enough to the true flow phenomenon research in the axial-flow pump, and design method is advanced inadequately.As the patent No. be: " front guide wheel vertical axial-flow pump " of ZL95103466.9, the patent No. is: " multipurpose asynchronous motor axial-flow pump " of ZL92106090.4, number of patent application is: 01109652.7 " built-in to the axial flow rotary pump ", the impeller blade of axial-flow pump is the axial-flow pump critical component, they are to adopt existing common lift method or singular point distribution to design to axial flow pump impeller vane, these design method all reckon without blade tip near zones such as shell and wheel hubs, ring-type boundary layer on the static shell wall and the lip-deep boundary layer of rotor blade and interfere mutually by the Clearance Flow between blade tip and the shell, and the secondary flow between the blade, formation comprises that being separated in the improper of interior complexity flows, produce the horse shoe shaped whirlpool, reveal various vortexs such as whirlpool and trailing vortex, above-mentioned these complicated flow factors, cause existing hydraulic model of axial-flow pump efficient on the low side, hydraulic loss is very big.

Summary of the invention:

The objective of the invention is to set up the flow model that holds water, use this flow model to design axial flow pump impeller vane, this impeller blade can be controlled separating of ring-type development of boundary layer on shell and the hub surface and blade suction surface top interlayer effectively, simultaneously can reduce blade tip load, reduce the influence of Clearance Flow, the shape of blade is conformed to better, to improve the efficient of axial-flow pump with actual flow.

Design method of the present invention is to consider the boundary layer at axial-flow pump impeller outer rim and impeller hub place and the influence in gap, it is characterized in that proposing following flow model, and its design fundamental equation is:

$C_y\frac{l}{t}=A(R,\mathrm{\δ})\·\frac{{2\mathrm{\ΔV}}_u}{W_{\∞}}\·\frac{1}{1+\mathrm{tg\λ}/\mathrm{tg}{\mathrm{\β}}_{\∞}}--\left(1\right)$

In the formula, C _yBe lift coefficient,

Be cascade solidity, all the other are flow parameter, and (R δ) for considering the boundary layer at impeller outer edge and impeller hub place and the correction factor of gap affects, is determined by following formula A.

Wherein, R is for calculating section radius, δ _hBe the thickness in the boundary layer of impeller hub section part, δ ₂Thickness for the boundary layer of wheel rim section part.δ _h, δ ₂Determine by following formula,

$\mathrm{\δ}\left(x\right)=[\frac{(3n+1)(2n+1)}{2n}{\mathrm{\β}}_0{]}^{\frac{n+1}{3n+1}}{\left(\frac{W_{\∞,i}}{\mathrm{\μ}/\mathrm{\ρ}}\right)}^{\frac{2n}{3n+1}}\·x--i=h,2--\left(3\right)$

X is taken as the size at blade exit place.Wherein n is the index power of velocity distribution rule in the definite axial-flow pump boundary layer of experiment, here n=7.8.The distorted shape that its end of blade of described impeller blade and leaf root part lean forward for lengthening.Described impeller blade bone line from the impeller blade end and root tilt 45 ° to Way in, and make impeller blade bone line lengthening 25%.

Aerofoil profile B end in the middle of described impeller blade bone line carries out the transition to gradually from A end end, the root C that carries out the transition to impeller blade from middle aerofoil profile B end holds again.

Description of drawings:

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

The conventional impeller blade airfoil structure of Fig. 1 axial-flow pump figure

Fig. 2 axial-flow pump impeller blade bone line schematic representation

Fig. 3 aerofoil vane blade structure figure that extends

Embodiment:

Figure 1 shows that the conventional airfoil structure figure of the impeller blade made from prior art.

Axial flow pump impeller vane bone line shown in Figure 2 for flow model according to the present invention is that fundamental equation (1), (2), (3) carry out the impeller blade parameter and flow calculating, draws and draws out after the impeller blade bone line parameter (basic parameter).Be the bone line for the afterbody A end from impeller blade carry out the transition to gradually in the middle of aerofoil profile B end, tilting to carry out the transition to the head C of impeller blade after 45 ° to Way in by middle aerofoil profile B end on the basis of AB section again, impeller blade bone line AC to the end.BC section bone line length is 25% of an AB section bone line length, the length that is to say bone line AC be bone line AB length 125%.On the basis of making the distortion bone line AC that leans forward, finish the lean forward aerofoil vane blade structure plan of distorted shape of as shown in Figure 3 lengthening.

Advantage of the present invention is: the axial flow pump impeller vane of the flow model construction design method design that proposes according to the present invention, promptly end of blade and leaf root part have adopted the distorted shape that lengthening leans forward.Can control separating of ring-type development of boundary layer on shell and the hub surface and blade suction surface top interlayer effectively, reduce blade tip load simultaneously, reduce the influence of Clearance Flow, the shape of blade is conformed to actual flow better.

Claims (4)

1, the present invention relates to a kind of axial flow pump impeller vane, it is characterized in that proposing following flow model, its design fundamental equation is:

$C_y\frac{1}{t}=A(R,\mathrm{\δ})\·\frac{2\mathrm{\Δ}{V}_u}{W_{\∞}}\·\frac{1}{1+\mathrm{tg\λ}/\mathrm{tg}{\mathrm{\β}}_{\∞}}---\left(1\right)$

In the formula, C _yBe lift coefficient,

Be cascade solidity, all the other are flow parameter, and (R δ) for considering the boundary layer at impeller outer edge and impeller hub place and the correction factor of gap affects, is determined by following formula A.

Wherein, R is for calculating section radius, δ _hBe the thickness in the boundary layer of impeller hub section part, δ ₂Thickness for the boundary layer of wheel rim section part.δ _h, δ ₂Determine by following formula.

$\mathrm{\δ}\left(x\right)=[\frac{(3n+1)(2n+1)}{2n}{\mathrm{\β}}_0{]}^{\frac{n+1}{3n+1}}{\left(\frac{W_{\∞,i}x}{\mathrm{\μ}/\mathrm{\ρ}}\right)}^{\frac{2n}{3n+1}}\·x---i=h,2---\left(3\right)$

X is taken as the size at blade exit place.Wherein n is the definite axial-flow pump limit of experiment

The index power of velocity distribution rule, here n=7.8 in the interlayer.

2, axial flow pump impeller vane according to claim 1 is characterized in that the distorted shape that its end of blade of impeller blade and leaf root part lean forward for lengthening.

3, axial flow pump impeller vane according to claim 1, it is characterized in that impeller blade bone line from the impeller blade end and root tilt 45 ° to Way in, and make impeller blade bone line lengthening 25%.

4, axial flow pump impeller vane according to claim 1 is characterized in that impeller blade bone line carries out the transition to middle aerofoil profile B end gradually from A end end, carries out the transition to the root C end of impeller blade again from middle aerofoil profile B end.

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