CN103104547A - Hydraulic unequal pump lift design method for gas-liquid two-phase nuclear main pump impeller - Google Patents

Abstract

The invention relates to a hydraulic unequal pump lift design method for a gas-liquid two-phase nuclear main pump impeller. The hydraulic unequal pump lift design method is characterized in that the theoretical pump lift of limited vanes of a front cover plate at the outlet of the impeller is equal to that of limited vanes of a rear cover plate at the outlet of the impeller when the theoretical pump lift of unlimited vanes of the front cover plate at the outlet of vanes is greater than that of unlimited vanes of the rear cover plate at the outlet of the vanes, a gas-liquid mixed medium is taken into account when the theoretical pump lift of the unlimited vanes is calculated, and main geometric parameters of the impeller are adjusted through certain constraint conditions, thereby meeting the requirements for nuclear main pump impeller design. According to the nuclear main pump impeller designed by using the hydraulic unequal pump lift design method, the gas-liquid mixed transportation capacity can be increased, so that a nuclear main pump can be guaranteed of safe and stable operation under the working condition of loss of coolant accidents.

Description

Gas-liquid two-phase flow core main pump impeller does not wait the lift Hydraulic Design Method

Affiliated technical field

The present invention relates to a kind of gas-liquid two-phase flow core main pump impeller and do not wait the lift Hydraulic Design Method, the unlimited blade theoretical head of front shroud that is particularly related to a kind of blade exit is during greater than the unlimited blade theoretical head of back shroud, and the gas-liquid two-phase flow core main pump impeller that the limited blade theoretical head of impeller outlet front and rear cover plate equates does not wait the lift Hydraulic Design Method.

Background technique

Since the eighties, the safety problem of atomic reactor has caused people's great attention, thereby has promoted the research of gas-liquid two-phase pump.When occurring the cooling liquid leakage in reactor, along with the reduction of cooling system internal pressure, cooling liquid comes to life, thereby coolant pump is moved under the gas-liquid two-phase stream mode.

At present the gas-liquid two-phase flow pump is not still had ripe design method, can't think that clean waterpump can design more reliably according to parameters such as given flow, lift, rotating speeds like that.Major requirement to the gas-liquid two-phase flow pump is the gas-liquid mixed ratio that improves its medium that can carry.

The conventional impellers design method presupposes, and for fear of harmful flowing, all streamline, theoretical head should be same numerical value in impeller.Think simultaneously, remain unchanged in the value of whole Exit-edge upper outlet laying angle.The static moment of each streamline is not identical, can draw thus, and correction factor also changes, and the speed of each streamline is also different, that is to say that the Exit-edge countershaft is not parallel as supposing.Change the static moment of given streamline, namely change the length of streamline, can revise to a certain extent work done factor, but the possibility of this moment is limited.Generally the streamline that is positioned at the impeller blade antetheca should be lengthened, but this has harmful effect to flow channel shape between the impeller inlet leaf.

Change correction factor, although also can reach constant speed, at this moment must change the blade exit laying angle along the constant supposition of exit edge of blade, determine like this Exit-edge location comparison difficulty.As specific speed n _s＜250 o'clock, Exit-edge was generally a straight line, if strive for making Exit-edge and streamline to be approximated to the right angle, should make Exit-edge become concavity.As specific speed n _s＞250 o'clock, in order to improve to a certain extent the shape of vane channel, streamline can be moved with respect to the impeller wall, this moment, Exit-edge just no longer can keep and shaft parallel, had namely taked impeller is flowed out the method that the limit is in tilted layout.Along with the increase of specific speed, the inclination angle also increases, and at this moment adopts the impeller outlet diameter that does not wait, be that the impeller outlet diameter of back shroud is less than front shroud impeller outlet diameter, can reduce the recirculating zone of impeller outlet, reduce the hydrodynamic force loss, make characteristic curve in small flow district's lift rising.

Difference due to the static moment of different streamlines in impeller, radius of curvature, Exit-edge position can cause the impeller by the design of the lifts such as the infinite number of blade, and the lift (Ht) at the blade exit place does not wait, and causes the Exit-edge movement disorder, reduces pump efficiency.

Summary of the invention

In order to overcome the deficiency of existing core main pump impeller design method, the invention provides a kind of gas-liquid two-phase flow core main pump impeller and do not wait the lift Hydraulic Design Method, adopt the impeller of the present invention's design to regulate the geometric parameter of impeller, reach the effect that the predicted performance curves of core main pump overlaps with the performance curve of requirement.The present invention has proposed first gas-liquid two-phase flow core main pump impeller and has not waited the lift Hydraulic Design Method.Find by the research to the conventional centrifugal pump Hydraulic Design Method, it is undesirable that the conventional centrifugal pump Hydraulic Design Method can cause the impeller blade outlet port to be flowed, the present invention adopts the lift method that do not wait first, and the core main pump is carried the gas-liquid two-phase medium when having considered loss of-coolant accident (LOCA), carry out the design of core main pump hydraulic, improve the gas-liquid delivery conveying capacity of core main pump, guarantee the safe and stable operation of nuclear reactor.

Technological scheme of the present invention:

Because every streamline in impeller is discrepant, this difference will cause the slip coefficient μ of each streamline in impeller not wait, and think unlimited blade theoretical head H _t∞Equate the limited blade theoretical head H of each streamline in actual impeller _tNot wait.When the centrifugal pump the Hydraulic Design, the limited blade theoretical head of each streamline H in impeller _tThe hydraulic loss that produces when equating is minimum, and such the Hydraulic Design is only best design result.Based on above-mentioned design theory, the present invention is from unlimited blade theoretical head H _t∞The prerequisite that does not wait is set out, and by revising the impeller geometric parameter, to adjust slip coefficient, makes limited blade theoretical head H _tEquate, reach employing and do not wait the lift method core main pump impeller to be carried out the purpose of the Hydraulic Design.Do not wait lift the Hydraulic Design basic skills to be:

By limited number of blade theoretical head H _tFundamental formular as can be known, H _tBe subjected to D ₁, D ₂, β ₁, β ₂, the parameter influence such as n, but this does not draw when considering that centrifugal action makes liquid can produce separation of flow phenomenon when front shroud flows.If consider separation of flow phenomenon and the factors such as jet-wake structure of blade exit, the H of fluid viscosity, front shroud _tAlso will be subjected to b ₁, b ₂, n _sImpact Deng geometric parameter.H _tWith H _t∞Relation set up by slip coefficient, but existing slip factor of centrifugal pumps formula is all to calculate by flow channel of axial plane center line (being mean value), does not consider the impact that the actual flow difference of each streamline produces.Therefore, need formula that can calculate respectively the slip coefficient of each streamline of model.

In actual engineering design, centrifugal pump impeller is divided into 2～3 streamlines designs, adopt the infinite number of blade theoretical head lineal shape distribution at blade exit place in the present invention, middle streamline lift is the mean value of front and rear cover plate lift.Therefore, only calculate in the following discussion the front and rear cover plate lift.Comprehensively relatively existing slip coefficient formula, considered the impact of viscosity due to the Stirling formula, therefore sets up the slip coefficient formula and be to carry out improvedly on Stirling formula basis, considers that the front and rear cover plate slip coefficient is different, has

Stirling (nineteen eighty-three) proposes following formula

$\mathrm{\&phi;}=\frac{{2\mathrm{\&pi;<figure-callout\; id="2"\; label="R"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}{{\mathrm{ZL}}_R}\frac{b_2}{b_1}[{\sin \mathrm{\&beta;}}_2-\frac{R_1}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}{\sin \mathrm{\&beta;}}_2]---\left(5\right)$

ψ in formula---head coefficient;

δ---coefficient, δ=1.473 φ ^2.16

φ---geometric parameter;

b ₁, b ₂---impeller inlet/outlet width;

L _R---the blade chord length, $L_R=\frac{R_2-R_1}{\sin \left(\frac{{\mathrm{\&beta;}}_1+{\mathrm{\&beta;}}_2}{2}\right)}.$

ψ in formula _a, ψ _b---the head coefficient of forward and backward cover plate, representation is

δ _a, δ _b---the design factor of forward and backward cover plate, representation is

φ _a, φ _b---the geometric parameter of forward and backward cover plate, representation is

b ₁, b ₂---impeller inlet/outlet width;

L _R---the blade chord length, representation is

By unlimited blade theoretical head formula, can calculate respectively forward and backward cover plate unlimited of blade exit

Blade theoretical head H _{Ta ∞}, H _{Tb ∞}Namely

H _{Th ∞ a}=[(1-x ₂) V _U2lau _2a-(1-x ₁) V _U1lau _1a+ x ₂V _U2gau _2a-x ₁V _U1gau _1a]/g front shroud

H _{Th ∞ a}=[(1-x ₂) V _U2lbu _2b-(1-x ₁) V _U1lbu _1b+ x ₂V _U2gbu _2b-x ₁V _U1gbu _1b]/g back shroud

(11)

X in formula---mass gas content rate, x=m _g/ m

m _g---gas phase mass flow,

m ₁---the liquid phase mass flow rate,

M---gas-liquid mixed phase mass flow rate, m=m _g+ m ₁,

The circumferential components of V---absolute velocity,

U---peripheral velocity.

According to above-mentioned slip coefficient formula, by limited blade theoretical head H _tFormula can be distinguished really

The limited blade theoretical head H of the forward and backward cover plate of fixed blade outlet _ta, H _tbNamely

$\left\{\begin{array}{c}{H}_{\mathrm{ta}}={\mathrm{\&mu;}}_a{H}_{t\&infin;a}\\ H_{\mathrm{tb}}={\mathrm{\&mu;}}_b{H}_{t\&infin;b}\end{array}\right.---\left(12\right)$

If the unlimited blade theoretical head of the front shroud of blade exit is during greater than the unlimited blade theoretical head of back shroud, the limited blade theoretical head of impeller outlet front and rear cover plate equates have following relationship to set up

H _ta∞＞H _tb∞ (13)

H _ta＝H _tb (14)

The impeller geometric parameter is adjusted, made it satisfy formula (13), (14), can reach by not waiting unlimited number of blade theoretical head design, thereby realize that limited blade theoretical head equates purpose.

Adjusting the impeller geometric parameter in fact is exactly the process of an optimal design.Optimal design requires satisfying under the prerequisite of specified performance, and making has a good cooperation between each geometric parameter of impeller, to obtain high as far as possible efficient.The restriction range of design variable produces material impact to optimum results, if the scope of design of variable is narrow, Optimum Points is omitted, if span is excessive, it does not meet design rule and the anufacturability of pump, therefore suitably the span of design variable is widened. and the constraint conditio in process of optimization of the present invention is:

25°＜β ₂＜60° (15)

$0.537{\left(\frac{n_s}{100}\right)}^{5/6}\sqrt[3]{\frac{Q}{n}}<{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">b</figure-callout>}}_2<0.815{\left(\frac{n_s}{100}\right)}^{5/6}\sqrt[3]{\frac{Q}{n}}---\left(16\right)$

$8{\left(\frac{n_s}{100}\right)}^{-0.5}\sqrt[3]{\frac{Q}{n}}<b_2<12{\left(\frac{n_s}{100}\right)}^{-0.5}\sqrt[3]{\frac{Q}{n}}---\left(17\right)$

$3.68\sqrt[3]{\frac{Q}{n}}<{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">b</figure-callout>}}_2<3.975\sqrt[3]{\frac{Q}{n}}---\left(18\right)$

30°＜β ₁＜40° (19)

$\frac{0.58Q}{4\sqrt[3]{\frac{Q}{n}}{\mathrm{<figure-callout\; id="1"\; label="K\; m"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">K</figure-callout>}}_m\sqrt{2\mathrm{gH}}}<{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">b</figure-callout>}}_1<\frac{0.98Q}{3.5\sqrt[3]{\frac{Q}{n}}{\mathrm{<figure-callout\; id="1"\; label="K\; m"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">K</figure-callout>}}_m\sqrt{2\mathrm{gH}}}---\left(20\right)$

Description of drawings

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

Fig. 1 is an embodiment's of patent of the present invention impeller axial plane sectional view.

Fig. 2 is same embodiment's impeller blade figure (throwing off the paddle wheel plane sectional view of seeing from front shroud of impeller towards back shroud of impeller after front shroud of impeller).

In figure: 1. front shroud of impeller, 2. back shroud of impeller, 3. impeller blade entrance width, 4. impeller blade exit width, 5. the outside diameter of impeller blade, 6. impeller inlet diameter, 7. blade import laying angle, 8. blade exit laying angle, 9. subtended angle of blade, 10. blade, 11. front side of vanes, 12. vacuum side of blades.In figure, a, b, c represent respectively front shroud streamline, back shroud streamline, center line of flow path.

Embodiment

Fig. 1 and Fig. 2 have determined this embodiment's impeller shape jointly.It is the same with most of centrifugal pump impellers, has front shroud of impeller (1) and back shroud of impeller (2), is a kind of double shrouded wheel.In the drawings, the convex surface of blade (10) is front side of vane (11), and the concave surface of blade is vacuum side of blade (12).The present invention adjusts the impeller geometric parameter by following relation, impeller blade entrance width b ₁(3), impeller blade exit width b ₂(4), the outside diameter D of impeller blade ₂(5), impeller inlet diameter D ₁(6), blade import laying angle β ₁(7), blade exit laying angle β ₂(8), subtended angle of blade ψ (9) makes this embodiment's core main pump performance satisfy the flow Q of optimum efficiency operating mode _BEP, the lift H of optimum efficiency operating mode _BEP, the requirement of wheel speed n.

$\mathrm{\&phi;}=\frac{{2\mathrm{\&pi;<figure-callout\; id="2"\; label="R"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}{{\mathrm{ZL}}_R}\frac{b_2}{b_1}[{\sin \mathrm{\&beta;}}_2-\frac{R_1}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}{\sin \mathrm{\&beta;}}_2]---\left(23\right)$

ψ in formula---head coefficient

δ---coefficient, δ=1.473 φ ^2.16

φ---geometric parameter;

b ₁, B ₂---impeller inlet/outlet width;

L _R---the blade chord length, $L_R=\frac{R_2-{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}{\sin \left(\frac{{\mathrm{\&beta;}}_1+{\mathrm{\&beta;}}_2}{2}\right)}$

H _{Th ∞ a}=[(1-x ₂) V _U2lau _2a-(1-x ₁) V _U1lau _1a+ x ₂V _U2gau _2a-x ₁V _U1gau _1a]/g front shroud

H _{Th ∞ a}=[(1-x ₂) V _U2lbu _2b-(1-x ₁) V _U1lbu _1b+ x ₂V _U2gbu _2b-x ₁V _U1gbu _1b]/g back shroud

(24)

$\left\{\begin{array}{c}{H}_{\mathrm{ta}}={\mathrm{\&mu;}}_a{H}_{t\&infin;a}\\ H_{\mathrm{tb}}={\mathrm{\&mu;}}_b{H}_{t\&infin;b}\end{array}\right.---\left(25\right)$

H _ta∞＞H _tb∞ (26)

H _ta＝H _tb (27)

Constraint conditio:

25°＜β ₂＜60° (28)

$0.537{\left(\frac{n_s}{100}\right)}^{5/6}\sqrt[3]{\frac{Q}{n}}<{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">b</figure-callout>}}_2<0.815{\left(\frac{n_s}{100}\right)}^{5/6}\sqrt[3]{\frac{Q}{n}}---\left(29\right)$

$8{\left(\frac{n_s}{100}\right)}^{-0.5}\sqrt[3]{\frac{Q}{n}}<{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">b</figure-callout>}}_2<12{\left(\frac{n_s}{100}\right)}^{-0.5}\sqrt[3]{\frac{Q}{n}}---\left(30\right)$

$3.68\sqrt[3]{\frac{Q}{n}}<{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">b</figure-callout>}}_2<3.975\sqrt[3]{\frac{Q}{n}}---\left(31\right)$

30°＜β ₁＜40° (32)

$\frac{0.58Q}{4\sqrt[3]{\frac{Q}{n}}{\mathrm{<figure-callout\; id="1"\; label="K\; m"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">K</figure-callout>}}_m\sqrt{2\mathrm{gH}}}<{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">b</figure-callout>}}_1<\frac{0.98Q}{3.5\sqrt[3]{\frac{Q}{n}}{\mathrm{<figure-callout\; id="1"\; label="K\; m"\; filenames="HSA00000862110800011.png"\; state="\{\{state\}\}">K</figure-callout>}}_m\sqrt{2\mathrm{gH}}}---\left(33\right)$

The performance curve shape that will reach according to designing requirement is with β ₂Adjust β when curve falls suddenly between 25 °～60 ° ₂Get the small value, β when curve is smooth ₂Get large value.For improving the gas-liquid delivery ability of core main pump impeller, should choose large as far as possible outlet laying angle.

The gas-liquid two-phase flow core main pump impeller that the design adopts does not wait the lift Hydraulic Design Method, the conveying of gas-liquid two-phase flow when going for loss of-coolant accident (LOCA).

In this embodiment, subtended angle of blade and the number of blade can require to select according to casting technique definite, in guaranteed performance, select the more number of blade, and usually getting the number of blade is 4～7.

Claims (5)

1. gas-liquid two-phase flow core main pump impeller does not wait the lift Hydraulic Design Method, according to core main pump performance being satisfied the flow Q of optimum efficiency operating mode _BEP, the lift H of optimum efficiency operating mode _BEP, the requirement of wheel speed n.It is characterized in that at the unlimited blade theoretical head of the front shroud of blade exit during greater than the unlimited blade theoretical head of back shroud, the limited blade theoretical head of impeller outlet front shroud equates with the limited blade theoretical head of back shroud, and the core main pump is carried the gas-liquid two-phase medium when having considered loss of-coolant accident (LOCA), and regulate the impeller main geometric parameters by following formula and constraint conditio, to satisfy the Centrifugal Impeller Design requirement.

$\mathrm{\&phi;}=\frac{{2\mathrm{\&pi;R}}_2}{{\mathrm{ZL}}_R}\frac{b_2}{b_1}[{\sin \mathrm{\&beta;}}_2-\frac{R_1}{R_2}{\sin \mathrm{\&beta;}}_2]---\left(3\right)$

H _{Th ∞ a}=[(1-x ₂) V _U2lau _2a-(1-x ₁) V _U1lau _1a+ x ₂V _U2gau _2a-x ₁V _U1gau _1a]/g front shroud

H _{Th ∞ a}=[(1-x ₂) V _U2lbu _2b-(1-x ₁) V _U1lbu _1b+ x ₂V _U2gbu _2b-x ₁V _U1gbu _1b]/g back shroud

(4)

$\left\{\begin{array}{c}{H}_{\mathrm{ta}}={\mathrm{\&mu;}}_a{H}_{t\&infin;a}\\ H_{\mathrm{tb}}={\mathrm{\&mu;}}_b{H}_{t\&infin;b}\end{array}\right.---\left(5\right)$

H _ta∞＞H _tb∞ (6)

H _ta＝H _tb (7)

Constraint conditio:

25°＜β ₂＜60° (8)

$0.537{\left(\frac{n_s}{100}\right)}^{5/6}\sqrt[3]{\frac{Q}{n}}<b_2<0.815{\left(\frac{n_s}{100}\right)}^{5/6}\sqrt[3]{\frac{Q}{n}}---\left(9\right)$

$8{\left(\frac{n_s}{100}\right)}^{-0.5}\sqrt[3]{\frac{Q}{n}}<b_2<12{\left(\frac{n_s}{100}\right)}^{-0.5}\sqrt[3]{\frac{Q}{n}}---\left(10\right)$

$3.68\sqrt[3]{\frac{Q}{n}}<b_2<3.975\sqrt[3]{\frac{Q}{n}}---\left(11\right)$

30°＜β ₁＜40° (12)

$\frac{0.58Q}{4\sqrt[3]{\frac{Q}{n}}{K}_{m1}\sqrt{2\mathrm{gH}}}<b_1<\frac{0.98Q}{3.5\sqrt[3]{\frac{Q}{n}}{K}_{m1}\sqrt{2\mathrm{gH}}}---\left(13\right)$

In formula:

μ---slip coefficient;

ψ---head coefficient;

K _m1---correction factor;

δ---coefficient, δ=1.473 φ ^2.16

φ---geometric parameter;

L _R---the blade chord length, $L_R=\frac{R_2-R_1}{\sin \left(\frac{{\mathrm{\&beta;}}_1+{\mathrm{\&beta;}}_2}{2}\right)};$

b ₁, b ₂---impeller inlet/outlet width;

D ₁, D ₂---impeller inlet/outlet diameter;

β ₁, β ₂---impeller blade inlet/outlet laying angle;

N speed, rev/min;

Q---operating point for design flow, m3/s;

H---operating point for design lift, rice;

X---mass gas content rate, x=m _g/ m

m _g---gas phase mass flow,

m ₁---the liquid phase mass flow rate,

M---gas-liquid mixed phase mass flow rate, m=m _g+ m ₁,

The circumferential components of V---absolute velocity,

U---peripheral velocity.

2. gas-liquid two-phase flow core main pump impeller does not wait the lift Hydraulic Design Method as claimed in claim 1, it is characterized in that at H _{Ta ∞}＞H _{Tb ∞}The time, H _ta=H _tbThe hydraulic loss that produces in impeller is minimum, and such the Hydraulic Design is only best design result.

3. gas-liquid two-phase flow core main pump impeller as claimed in claim 1 does not wait the lift Hydraulic Design Method, it is characterized in that: the performance curve shape that will reach according to designing requirement, and with β ₂Adjust β when curve falls suddenly between 25 °～60 ° ₂Get the small value, β when curve is smooth ₂Get large value.For improving the gas-liquid delivery ability of core main pump impeller, should choose large as far as possible outlet laying angle.

4. gas-liquid two-phase flow core main pump impeller as claimed in claim 1 does not wait the lift Hydraulic Design Method, it is characterized in that: impeller blade import laying angle β ₁, adjust between 30 °～40 ° without the separation of flow by optimum efficiency point.

5. gas-liquid two-phase flow core main pump impeller as claimed in claim 1 does not wait the lift Hydraulic Design Method, subtended angle of blade and the number of blade can require to select to determine according to casting technique, in guaranteed performance, select the more number of blade, usually getting the number of blade is 4～7.

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