CN101881284A - Axial flow pump guide vane body with high specific speed - Google Patents

Abstract

The invention discloses an axial flow pump guide vane body with high specific speed, overcoming the deficiencies that the traditional axial flow pump guide vane body with high specific speed has larger hydraulic loss, resulting in lower efficiency of a water pump. In the invention, a diffusion angle of a conical tube of the guide vane body is enlarged to enable a single-edge diffusion angle thereof to be ranged from 6 degrees to 10 degrees; because the diffusion degree of the guide vane body is increased, the flow rate is lowered on the basis of ensuring not to cause side wall flow separation, thereby efficiently lowering the hydraulic loss of the guide vane body and enhancing the efficiency of the pump; and also because the diffusion angle of the guide vane body is enlarged and the outlet diameter is increased, a flowing space of a latter water outlet channel is also increased, the hydraulic loss of the water outlet channel is lowered, and the pump device efficiency is further improved.

Description

Axial flow pump guide vane body with high specific speed

Technical field:

The present invention relates to a kind of high specific speed axial-flow pump rear guide vane body, belong to the hydraulic machinery field.

Background technique:

Stator is important composition parts in the axial-flow pump, and liquid stream has certain outlet vortex energy after flowing out axial-flow pump impeller, account for 6%～20% (specific speed n of total energy _s=1600～500).If the liquid that rotates directly enters penstock, the kinetic energy of rotation will total loss fall in pipeline.The effect of axial-flow pump stator is exactly that most of vortex with the impeller outlet place can convert the pressure energy effectively to, and therefore, diffuser has bigger influence to the axial-flow pump performance.

Water pump specific speed n _sRepresentation is:

$n_s=3.65\frac{n\sqrt{Q}}{H^{3/4}}---\left(1\right)$

In the formula, n is a rotating speed; Q is a flow; H is a lift.

The equation of the actual lift H of axial-flow pump is:

$H=\frac{\mathrm{\π}\·n\·D\·{\mathrm{\η}}_h}{60g}(V_{u2}-V_{u1})---\left(2\right)$

In the formula, D is an impeller diameter; η _hBe hydraulic efficiency; V _U1, V _U2Be respectively impeller and import and export absolute velocity component along the circumferential direction in the velocity triangle, usually V _U1=0; G is a gravity accleration; π is a Ratio of the circumference of a circle to its diameter.

Know that by formula (1) and formula (2) Q is certain when flow, rotation speed n is certain, and impeller inlet does not have prewhirls, and changes when little specific speed n in hydraulic efficiency _sHigh more, then lift H is low more, means V _2uMore little, the callable energy of stator is more little.

A large amount of hydraulic model test digital proofs, the contrast rotation speed n _sAxial-flow pump about=900～1000, stator accounts for 10% of stagnation pressure greatly with the ability that rotation function is converted into the pressure energy.Along with specific speed increases, this ability of stator will continue to descend.

And stator also can bring corresponding hydraulic loss in recovered energy, and as the vane inlet impact loss, shape loss and wake flow mix and ooze loss etc.Higher specific speed axial flow lift of pump is low relatively, then its V _2uAlso little, stator reclaims can be relatively also little, but the various losses that stator brings are then constant substantially, may cause like this installing that the total efficiency of water pump can not get effectively improving even also may descending behind the stator.Contrast existing outstanding hydraulic model of axial-flow pump parameter at present can be found, at specific speed n _sSurpass after 1000, its efficient begins remarkable reduction, mainly be because the lift that diffuser lost accounts for the ratio of total head to be increased, and the recoverable energy of stator institute is due to the reason of minimizing.

At present, China's axial-flow pump impeller has reached higher design level, as the patent No. be: " axial flow pump impeller vane " of ZL02133456.0, but ubiquity is to the not enough problem of diffuser research, particularly the axial-flow pump diffuser to high specific speed still designs according to the diffuser design method of low specific speed, causes the axial-flow pump efficient of the high specific speed of low lift on the low side.

Summary of the invention:

In order to overcome existing axial flow pump guide vane body with high specific speed hydraulic loss large percentage, deficiency that pump efficiency is lower, the invention provides a kind of Optimization Design of axial flow pump guide vane body with high specific speed, can effectively reduce the hydraulic loss of diffuser, the efficient of elevator pump and pump-unit.

Along with the raising of axial-flow pump specific speed, the absolute velocity of impeller outlet fluid is reducing at the component of circumferencial direction, so the guide vane import laying angle α of diffuser ₃Increasing.The angle of flare ε of runner can be definite by following formula between a certain cylindrical stream surface adjacent blades in the diffuser:

$\tan \frac{\mathrm{\ϵ}}{2}=\frac{t(1-{\sin \mathrm{\α}}_3)}{2l}---\left(3\right)$

In the formula, l/t is a cascade solidity.

By formula (3) as can be known, along with α ₃Increase, ε is reducing.Specific speed reaches after 1000, and ε mean value only is 2 °～3 °.At present, when designing, gets diffuser center angle of flare θ≤(6 °～10 °) (see " modern pump technical manual ", Guan Xingfan writes, Yuhang Publishing House, 1995) of conic diffuse, and common owing to be subjected to diffuser outlet diameter D when actual design ₄Get the restriction of standard pipe size, θ probably gets about 6 ° usually, does not make full use of diffusion space.And the minimum value of the resistance coefficient of taper increaser is in fact in the scope of θ=4 °～12 °, in order to make full use of diffusion space, and desirable here big value.

And the equivalent angle of flare of tackling the runner between adjacent two guide vanes when determining the diffusance of diffuser is adjusted.Because the diffuser of high specific speed axial-flow pump is less at the angle of flare ε between the adjacent guide vane sheet on the same stream interface, one side not diffusion again in hub side, to answer this in order fully spreading, can be provided with the angle of flare of the single face in the outside as the center angle of flare.

A kind of axial flow pump guide vane body with high specific speed of the present invention is characterized in that strengthening the angle of flare θ of diffuser conical pipe, makes its conventional Δ θ that increases, and its monolateral angle of flare is satisfied

The invention has the beneficial effects as follows, because the increase of diffuser diffusance, reduced flow velocity guaranteeing not cause on the basis of the limit wall separation of flow, because square being directly proportional of hydraulic loss and flow velocity, so can effectively reduce the hydraulic loss of diffuser, the efficient of raising pump; The axial-flow pump of high specific speed is usually used in large-scale low lift pumping plant simultaneously, the outlet diameter of diffuser does not need to be subjected to the restriction of standard pipe size, outlet connects the outlet passage with diffuser usually, because the increasing and the outlet diameter of diffuser diffusion angle increase, make the fluid space of crossing of the outlet passage of back also obtain increase, reduced the hydraulic loss of outlet passage, pump assembly efficiency is further improved.

Description of drawings:

Fig. 1 is an axial-flow pump diffuser cross-sectional view;

Fig. 2 is molded lines on the cylindrical stream surface of R at radius for the diffuser blade;

Fig. 3 is the vertical-type axial-flow pump apparatus structure schematic representation of elbow water inlet, straighttube-type water outlet, and top (1) is sectional drawing, and bottom (2) are planimetric map;

Fig. 4 is the vertical-type axial-flow pump apparatus structure schematic representation of elbow water inlet, hydrocone type water outlet, and top (1) is sectional drawing, and bottom (2) are planimetric map;

1 is outlet passage among the figure, the 2nd, and diffuser, the 3rd, impeller, the 4th, water inlet flow channel;

Dotted portion is represented the molded lines after the diffuser conical pipe strengthens the diffusion angle among the figure.

Embodiment:

The present invention is further described below in conjunction with accompanying drawing.

Embodiment 1, and the application behind the diffuser process increasing angle of flare in the vertical axial-flow pump-unit of straighttube-type water outlet is seen shown in Figure 3.Because the diffusion angle of diffuser strengthens, and makes the outlet enlarged diameter, cross fluid space for follow-up straighttube-type outlet passage has increased, but do not increase the Extreme breadth of outlet passage, do not need to increase construction investment.Because the outlet passage increasing of crossing fluid space, the reduction of flow velocity reduces hydraulic loss greatly, because the hydraulic loss of outlet passage accounts for 70%～80% of whole inlet and outlet channels losses in the large-scale low lift pumping plant, so effective elevator pump unit efficiency.

Embodiment 2, and the application behind the diffuser process increasing angle of flare in the vertical axial-flow pump-unit of hydrocone type water outlet is seen shown in Figure 4.Because the increase of diffuser outlet diameter, make the fluid space of crossing of outlet passage also obtain increase, but only make the integral width of siphon outlet passage forward part gradually expanding section obtain increase, do not increase the Extreme breadth of runner, pump assembly efficiency is effectively promoted.

Claims (1)

1. axial flow pump guide vane body with high specific speed, it is characterized in that: strengthened the angle of flare of diffuser conical pipe, making its monolateral angle of flare is 6 °～10 °, can enlarge the fluid space of crossing of diffuser and subsequent segment outlet passage, reduce flow velocity, the efficient of elevator pump and pump-unit.

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