CN105626573A - Designing method of fish-friendly axial flow pump based on fish survival rate prediction - Google Patents

Abstract

The invention provides a designing method of a fish-friendly axial flow pump based on fish survival rate prediction. A relation between a pump design parameter and the fish passing survival rate is predicted by adopting a mathematical model, and thus a fish-friendly design of an axial flow pump is guided. The mathematical model is mainly composed of the blade leading edge impact probability and the impact death rate; the impact probability is a ratio of the time that fishes pass through the cross section of passage of the blade leading edge and the time needed by an impeller rotating around a blade pitch; the impact death rate is relevant to the impact velocity, the fish length and the thickness of the blade leading edge; and the impact velocity adoptsa velocity component of a vertical leading edge. The fish-friendly axial flow pump design comprises the following steps: lowering the blade leading edge impact probability by adopting two blade impellers, lowering the impact death rate by adopting the blade leading edge with linear sweepforward protraction, and ensuring good hydraulic performance by virtue of airfoil parameter design. According to the designing method, a fish survival rate prediction model is high in goodness of fit to an experiment value, and the fish-friendly axial flow pump designed by guidance can greatly lower the fish death rate.

Description

The method of design of a kind of fish friendly propeller pump based on the prediction of fish survival rate

Technical field

The present invention relates to hydraulicefficiency machinery technical field, particularly relate to the method for design of a kind of fish friendly propeller pump based on the prediction of fish survival rate, be applicable to the big-and-middle-sized propeller pump design having all kinds of fish to pass through.

Background technology

Pumping plant is widely used in controlling flood and draining flooded fields and agricultural irrigation, and much domestic along the river along Haicheng City, the country of Europe hypsography low-lying, the consumption of pumping plant is very huge. But a negative impact is, the fish stock in ocean, river is by suffering inevitable damage and death during pumping plant, and then affects the migration of fish and migrate. The instruction on protection fish habitat ground has just been put into effect as far back as European Parliament in 2000; comprise for fish provide unobstructed migration; EU Water Framework Directive also highlights the importance that various water obstacle is changed into fish friendly; in the coming years, the regulation strengthening remedying fish in imminent danger also will perform in EU countries. Under the background that current many countries pay attention to ecological protection, the concern that the exploitation of fish friendly pump and pumping plant is also got more and more.

Through retrieval, not relevant fish are by the mathematical model of the prediction of survival rate after propeller pump, and in the method for design that propeller pump is relevant, nearly all for improving pump efficiency, pump stability, the dirt method of design by running under ability or multi-state, if publication number is the patented technology of CN102748300A, CN104005983A, CN103452912A, all do not consider that pump has live fish in actual motion and passes through, and a kind of fish friendly pump of optimization design. The patented technology that publication number is CN104613001A proposes the Eco-friendly propeller pump structure by fish, but does not provide method of design. Therefore, existing method of design can not solve and improve this important ecological problem of fish survival rate.

Summary of the invention

For problems of the prior art, the present invention provides the method for design of a kind of fish friendly propeller pump based on the prediction of fish survival rate, to improve the survival rate of fish by big-and-middle-sized propeller pump, avoids fish damage and death.

The technical scheme of the present invention is: the method for design of a kind of fish friendly propeller pump based on the prediction of fish survival rate, adopt mathematical model prediction fish by the survival rate after propeller pump, obtain the relation between blade design variable and fish survival rate, and thus instruct the design of fish friendly propeller pump. Described mathematical model mainly comprises the prediction of blade inlet edge hit probability and clashes into mortality ratio prediction, focuses on the selection of shock speed. Described fish friendly propeller pump designs based on mathematical model, adopts two blade impellers to reduce blade inlet edge hit probability, adopts the blade inlet edge that linear sweepforward is protracted to reduce and clashes into mortality ratio.

Fish are thought of as the stiff object of one-dimensional linear by described mathematical model, and without subjective motion, and without Relative sliding between liquid stream, length is L_fishFish and the common axial velocity of liquid stream be v_m1, then fish are t by blade inlet edge place flow section required time_fish, Q is pumping capacity, R₁And R₂It is respectively blade inlet edge wheel hub and the radius at wheel rim place.

$t_{fish}=\frac{L_{fish}}{v_{m1}}=\frac{\mathrm{\π}(R_2^2-R_1^2)L_{fish}}{Q}$

Wheel speed is Nr/min, and the number of blade is that to turn over a blade apart from s required time be t for the impeller of n_blade, r is blade inlet edge any point radius, and u is blade circumferential speed.

$t_{blade}=\frac{s}{u}=\frac{2\mathrm{\π}r/n}{N2\mathrm{\π}r/60}=\frac{60}{nN}$

Pass through t_fishWith t_bladeRatio obtain leading edge hit probability

Leading edge hit probability is limited within 100%, P_strike=min [1, P'_strike]

After being subject to blade inlet edge shock, there is the meeting of part fish dead, affect this ratio f_strikeThe most important factor clashes into speed v exactly, and the shock speed that the present invention chooses is the velocity component of vertical leading, gets the component in blade circumferential speed vertical leading direction respectivelyCos �� and liquid flow shaft are to the component in speed vertical leading directionCos �� carries out vector superposition, namely For circular frequency vector, r is leading edge any point radius, and �� is the angle in front view blade tangential velocity direction and vertical leading direction,For liquid flow shaft is to velocity vector, �� be in axis projection liquid flow shaft to the angle of velocity reversal and vertical leading direction.

Shock rate integrating is averaging by leading edge

The shock mortality ratio f that data analysis according to pumping plant monitoring obtains_strikeWith on average clash into speed v_a, fish length L_fish, relation between blade inlet edge thickness d,A, b are coefficient, and value is such as following table

Fish survival rate C=1-P_strikef_strike

The linear sweepforward of described blade inlet edge is protracted, its sweepforward degreeBeing defined as in impeller front view, leading edge wheel rim place, to the angle of leading edge wheel hub, meetsSweepforward formal definition is the velocity of variation k of sweepforward angle �� with leading edge radius R₁, meet k₁For constant; The degree E of protracting is defined as in impeller axis projection, and leading edge wheel rim place, to the axial distance of leading edge wheel hub, meets 0.2R₂<E<0.4R₂, formal definition of protracting is the velocity of variation k of the axial distance L of leading edge with radius R₂, meet k₂For constant.

Described fish friendly propeller pump method of design, by designing the cross section aerofoil profile of blade on the cylinder of different radii, generates intact leaf.

Blade different cross section aerofoil profile chord length l value is 1.6R in wheel hub₂, linearly it is increased to the 3R at wheel rim place₂��

Blade different cross section place liquid flow shaft to speed isConsider volumetric efficiency ��_vAnd blade excretion coefficient ��, volumetric efficiency gets definite value 0.98, and blade exclusion coefficient value is 0.87 be linearly increased to the 0.95 of wheel rim place in wheel hub.

Blade different cross section place blade exit liquid stream circumferential speed component isAdopt 1.5��1.7 times of designs lift H, hydraulic efficiency ��_hValue linearly reduces to the 0.86 of wheel rim by the 0.9 of wheel hub, and circular rector correction factor �� is linearly increased to the 1 of intermediate cross-section by the 0.8 of wheel hub, to be more linearly increased to the 1.25, u of wheel rim place be blade circumferential speed.

Inlet blade angleAdditional angle is 1 �� in wheel hub and is linearly increased to 3 ��, v_m1For vane inlet liquid flow shaft is to velocity component.

Vane exit angleAdditional angle perseverance is 1 ��, v_m2For blade exit liquid flow shaft is to velocity component.

Blade and blade angle of chord ��_L=(��₁+��₂)/2��

According to leading edge sweepforward degreeSweepforward form k₁, protract degree E and front stretched form k₂, do to offset to form the blade inlet edge that linear sweepforward is protracted accordingly by aerofoil profile in aerofoil profile stretch-out view.

The useful effect of the present invention:

(1) fish are by the survival rate mathematical prediction model after propeller pump, through verification experimental verification can relation between accurate response pump design variable and fish survival rate, can design fish friendly propeller pump. Can obtaining according to mathematical model, the number of blade and rotating speed affect the main factor of blade inlet edge hit probability, and shock speed is the main factor that mortality ratio is clashed in impact.

(2) design fish friendly propeller pump based on fish survival rate mathematical prediction model, two blade impellers can much slower they strike probability, reduce compared with hit probability with adopting slow speed of revolution impeller, higher lift can be ensured; The linear sweepforward of blade inlet edge is protracted and can be clashed into speed by much slower leading edge each point, thus reduces shock mortality ratio. By mathematical model prediction, the propeller pump under same design parameter (external diameter, rotating speed, flow, lift etc.) is after fish friendly designs, and fish survival rate improves more than 50%.

(3) the present invention is when designing vane airfoil profile parameter, and chord length l value reduces the dense degree of leaf grating compared with I, on the one hand control blade axial height, reduces blade acting area on the other hand, reduces hydraulic loss; 1.5��1.7 times of design lifts are adopted to calculate vane exit angle ��₂, make up the liquid stream deflection deficiency that less chord length value causes.

Accompanying drawing explanation

Fig. 1 is standard axial-flow pump impeller side-view.

Fig. 2 is standard axial-flow pump impeller front view.

Fig. 3 is fish survival rate mathematical prediction model schematic diagram.

Fig. 4 is fish survival rate mathematical prediction model axial velocity decomposing schematic representation

Fig. 5 is fish survival rate mathematical prediction model circumferential speed decomposing schematic representation

Fig. 6 is fish friendly axial-flow pump impeller schematic diagram.

Fig. 7 is fish friendly axial-flow pump impeller front views.

Fig. 8 is fish friendly axial-flow pump impeller axis projection.

Fig. 9 is blade section schematic diagram.

Figure 10 blade section aerofoil profile stretch-out view.

Description of reference numerals is as follows: 1-axial-flow pump hub disks, 2-blade inlet edge, 3-blade, 4-blade trailing edge, 5-blade inlet edge place flow section.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment, the present invention is further illustrated.

Fish survival rate mathematical prediction model is illustrated by Fig. 1 to Fig. 5. Fig. 1 is standard axial-flow pump impeller side-view, and Fig. 2 is standard axial-flow pump impeller front view, by its blade (3) by planar development, as shown in Figure 3. Fish are thought of as the stiff object of one-dimensional linear, and without subjective motion, and and without Relative sliding between liquid stream, fish are t by the time at blade inlet edge place flow section (5)_fish, it is t that impeller turns over a blade apart from required time_blade, both ratios can obtain blade inlet edge hit probability P '_strike. It is being subject in the fish that blade inlet edge (2) clashes into, is having the meeting of part fish dead, this ratio f_strikeWith shock speed v and fish length L_fishRelevant with the ratio of blade inlet edge (2) thickness d, obtain f according to the data regression of pumping plant monitoring_strikePredict the mortality ratio being subject to clashing into rear fish. For for-swept blade, clash into the velocity component that speed v should get vertical leading, in Fig. 3 axial velocity decomposing schematic representation, get vertical componentIn Fig. 4 circumferential speed decomposing schematic representation, get vertical componentBy vectorWithObtain the shock velocity distribution of leading edge each point after superposition, after its integration is averaging, can obtain and on average clash into speed v_a. This predictive model is through verification experimental verification, can relation between accurate response pump design variable and fish survival rate, can obtaining according to mathematical model, the number of blade and rotating speed affect the main factor of they strike probability, and they strike speed is the main factor affecting they strike mortality ratio. And adopt two blade impellers can much slower they strike probability, reduce compared with hit probability with adopting slow speed of revolution impeller, higher lift can be ensured; The linear sweepforward of blade inlet edge (2) is protracted and can be clashed into speed by much slower leading edge each point, thus reduces shock mortality ratio.

Based on the mathematical model of fish survival rate prediction, the linear sweepforward of blade inlet edge (2) being protracted, fish friendly axial-flow pump impeller schematic three dimensional views is as shown in Figure 6. Specifically, sweepforward degreeBeing defined as in impeller front view 7, leading edge wheel rim place Y point, to the angle of leading edge wheel hub G point, meetsSweepforward formal definition is the velocity of variation of sweepforward angle �� with leading edge radius RMeet k₁For constantThe degree E of protracting is defined as in impeller axis projection 8, and leading edge wheel rim place Y point, to the axial distance of leading edge wheel hub G point, meets 0.2R₂<E<0.4R₂, formal definition of protracting be in leading edge each point axially distance L with the velocity of variation of radius RMeet k₂For constant E/ (R₂-R₁)��

Fish friendly propeller pump method of design, by designing the cross section aerofoil profile of blade on the cylinder of different radii, generates intact leaf. Different cross section aerofoil profile parameter adopts the design of streamline method, and chord length l gets smaller value (1.6R₂��3R₂) the dense degree of leaf grating can be reduced, control blade axial height on the one hand, reduce blade acting area on the other hand, reduce hydraulic loss, now blade acting is less, and the deflection of liquid stream is not enough, adopts 1.5��1.7 times of design lifts to calculate blade exit liquid stream circumferential speed component v_u2, circular rector correction factor �� is linearly increased to the 1 of intermediate cross-section by the 0.8 of wheel hub, is more linearly increased to the 1.25 of wheel rim place.

For designing the blade inlet edge that linear sweepforward is protracted, each for blade cross section aerofoil profile having been done corresponding skew, skew amount is by leading edge sweepforward degreeSweepforward form k₁, protract degree E and front stretched form k₂Determine. Specifically, protract (k with linear sweepforward₁, k₂For constant), sweepforward degreeBeing 60 ��, the degree E of protracting is 0.3R₂For example, Fig. 9 is blade section schematic diagram, the plane outspread drawing in i-i cross section and j-j cross section is as shown in Figure 10, taking i-i cross section aerofoil profile as benchmark, j-j cross section aerofoil profile respectively against impeller sense of rotation (in figure be level to the right) skew 20 ��, along liquid flow path direction (be straight up in figure) skew 0.1R₂, other cross sections offset in the same fashion, form the blade inlet edge that linear sweepforward is protracted. The fish survival rate predictive model that the present invention proposes and experimental value coincide and spend height, and the fish friendly propeller pump of design can much slower fish kills rate.

Claims (4)

1. a method of design for the fish friendly propeller pump predicted based on fish survival rate, comprises the steps:

S1: set up the mathematical model between fish survival rate and propeller pump design variable;

S2: the parameter designing optimizing propeller pump based on the mathematical model between fish survival rate and propeller pump design variable.

2. the method for design of a kind of fish friendly propeller pump based on the prediction of fish survival rate according to claim 1, it is characterised in that, the establishment method of the mathematical model between described fish survival rate and propeller pump design variable is as follows:

S3: fish are thought of as the stiff object of one-dimensional linear, without subjective motion, and and without Relative sliding between liquid stream, blade inlet edge (2) hit probability P '_strikeFor fish are by the time t at blade inlet edge place flow section (5)_fishA blade is turned over apart from s required time t with impeller_bladeRatio, then:

$t_{fish}=\frac{L_{fish}}{v_{m1}}=\frac{\mathrm{\&pi;}(R_2^2-R_1^2)L_{fish}}{Q}$

$t_{blade}=\frac{s}{u}=\frac{2\mathrm{\&pi;}r/n}{N2\mathrm{\&pi;}r/60}=\frac{60}{nN}$

${P^{\&prime;}}_{strike}=\frac{t_{fish}}{t_{blade}}=\frac{\mathrm{\&pi;}(R_2^2-R_1^2)L_{fish}nN}{60Q}$

Wherein, L_fishFor fish length, v_m1For fish and liquid stream are in the common axial velocity component in vane inlet place, Q is pumping capacity, R₁And R₂Being respectively blade inlet edge wheel hub and the radius at wheel rim place, N is wheel speed, and r/min, n are impeller vane number, and r is blade inlet edge any point radius, and u is blade circumferential speed;

S4: be subject to the fish kills rate f after blade inlet edge (2) shock_strikeBeing obtained by monitoring data regression analysis, the mathematical relation between itself and the design variable of propeller pump is:

$f_{strike}=\&lsqb;aln\left(\frac{L_{fish}}{d}\right)+b\&rsqb;(v_a-4.8)$

$v_a={\&Integral;}_{R_1}^{R_2}\frac{v}{R_2-R_1}dr$

Wherein, a, b are constant coefficient, L_fishFor fish length, d is edge thickness before axial flow pump blade inner, v_aFor on average clashing into speed, v is that blade inlet edge any point clashes into speed;

S5: the mathematical model obtaining fish survival rate C and propeller pump design variable according to step S3 and step S4 is C=1-P_strikef_strike��

3. the method for design of a kind of fish friendly propeller pump based on the prediction of fish survival rate according to claim 2, it is characterized in that, in described step S4, blade inlet edge any point clashes into speed v gets the velocity component being perpendicular to leading edge, gets the component in blade circumferential speed vertical leading direction respectivelyWith the component of liquid flow shaft to speed vertical leading directionCarry out vector superposition, namely $v=|\stackrel{\&RightArrow;}{\mathrm{\&omega;}}rcos\mathrm{\&alpha;}+{\stackrel{\&RightArrow;}{v}}_{m1}cos\mathrm{\&beta;}|;$

Wherein:For circular frequency vector, r is leading edge any point radius, and �� is blade tangential velocity direction and the angle in vertical leading direction,For liquid flow shaft is to velocity vector, �� be in axis projection liquid flow shaft to the angle of velocity reversal and vertical leading direction.

4. the method for design of a kind of fish friendly propeller pump based on the prediction of fish survival rate according to claim 1, it is characterised in that,

Described fish friendly propeller pump adopts two blade impellers, and the linear sweepforward of blade inlet edge (2) is protracted, sweepforward degreeMeetSweepforward form k₁For sweepforward angle �� is with the velocity of variation of leading edge radius R, and meet hereinThe degree E of protracting meets 0.2R₂<E<0.4R₂, front stretched form k₂For the axial distance L of each point in leading edge is with the velocity of variation of radius R, and meet k herein₂=E/ (R₂-R₁), wherein R₁And R₂It is respectively blade inlet edge wheel hub and the radius at wheel rim place; Described fish friendly axial flow pump blade inner different cross section aerofoil profile chord length l value is 1.6R in wheel hub₂, linearly it is increased to the 3R at wheel rim place₂;

Blade different cross section place liquid flow shaft to speed isVolumetric efficiency ��_vGetting definite value 0.98, blade excretion coefficient �� value is 0.87 be linearly increased to the 0.95 of wheel rim place in wheel hub;

Blade different cross section place blade exit liquid stream circumferential speed component isAdopt 1.5��1.7 times of designs lift H, hydraulic efficiency ��_hValue linearly reduces to the 0.86 of wheel rim by the 0.9 of wheel hub, and circular rector correction factor �� is linearly increased to the 1 of intermediate cross-section by the 0.8 of wheel hub, is more linearly increased to the 1.25 of wheel rim place;

Described inlet blade angleInlet blade angle additional angle is 1 �� in wheel hub and is linearly increased to 3 ��; Vane exit angleVane exit angle additional angle perseverance is 1 ��; Leaf angle of chord ��_L=(��₁+��₂)/2; Wherein: u is blade circumferential speed, v_m1For vane inlet liquid flow shaft is to velocity component, v_m2For blade exit liquid flow shaft is to velocity component, v_u2For blade exit liquid stream circumferential speed component;

According to leading edge sweepforward degreeSweepforward form k₁, protract degree E and front stretched form k₂, do to offset to form the blade inlet edge that linear sweepforward is protracted accordingly by aerofoil profile in aerofoil profile stretch-out view.