CN103500265B - A kind of definite method of Wind Tunnel Contraction curve - Google Patents

Abstract

The invention provides a kind of definite method of Wind Tunnel Contraction curve, the radius of curvature of given contraction section entrance size, outlet size, contraction section length and contraction section outlet, can be from contraction section entrance, set gradually the mode of cylinder curve, Article 1 biquadratic curve, conic section, Article 2 biquadratic curve, obtain the curve of contraction section. According to the contraction section curve of the inventive method design, be applicable to subsonic wind tunnel, supersonic wind tunnel, whole curvature of curve is completely continuous, and the curvature at entrance and exit place is consistent with the curvature of front and back parts, realizes perfect connection. Curve front portion can not shunk very steep, and outlet does not also produce overshoot phenomenon, can overcome the deficiency of existing contraction section curve. Exit flow is uniformly distributed.

Description

A kind of definite method of Wind Tunnel Contraction curve

Technical field

A kind of definite method that the present invention relates to Wind Tunnel Contraction curve, belongs to fluid dynamic technical field.

Background technology

The effect of Wind Tunnel Contraction is evenly to accelerate air-flow, and the air-flow of stable section is accelerated to subsonic wind tunnel test section to be neededThe flow velocity of wanting, or in super/hypersonic wind tunnel, air-flow is accelerated to the velocity of sound. In the forties in last century, people are just to wind-tunnelContraction section Curve Design is studied, and obtains the algorithm of multiple contraction section curve. The common ground of these algorithms is given oneAxial velocity profile, according to the fundamental equation of ideal flow, calculates whole flow field, then in this flow field, selects one completelyThe streamline that foot shrinkage ratio requires is as contraction section. Even some method has adopted the conformal projection of complex function to obtain. Above thisA little algorithms are quite complicated, are not easy to the utilization in engineering. Calculate for simplifying, when design, theory is derived and obtained under specific circumstancesFormula be directly used in design. In contraction section curve, conventional curve has pungent this base curves in Vito, Vito Xin Siji to move axle at presentCurve, bicubic curve, cubic curve and quintic curve.

Now, in conventional contraction section curve, all there is certain shortcoming or deficiency. Pungent this base curves in Vito shrinks very in front portionSuddenly, be similar to straight at back segment. Air-flow shrinks suddenly like this, can produce adverse pressure gradient, is unfavorable for obtaining uniform air-flow. DimensionTuo Xinsiji moves axial curve and is to a certain degree being eased, but addresses this problem on not having completely. Bicubic curve and fiveInferior curve import is shunk smoother, and muzzle velocity has overshoot phenomenon. The entrance of cubic curve can not with stable section smooth connection,The first derivative of junction is discontinuous, can cause flow separation and affect flow field quality. In super/hypersonic wind tunnel, existingThe radius of curvature of contraction section curve outlet and the radius of curvature of supersonic speed expansion segment curve are unequal, and contraction section outlet can not be level and smoothBe transitioned into supersonic speed section, affect the flow field quality of whole wind-tunnel.

Summary of the invention

Technology of the present invention is dealt with problems: overcome the deficiencies in the prior art, determining of a kind of wind-tunnel shrinkage curve is providedMethod, the contraction section curve that overcomes prior art in front portion or rear portion shrink very steep, entrance can not be with stable section in smoothing junction andThe radius of curvature of outlet and the unequal problem of radius of curvature of supersonic speed expansion segment curve, by arranging cylindrical section curve, theArticle one, biquadratic curve, conical section curve and Article 2 biquadratic curve obtain contraction section curve.

Technical solution of the present invention:

A definite method for Wind Tunnel Contraction curve, comprises the steps:

(1) Wind Tunnel Contraction appearance curve being divided into four parts, is respectively cylindrical section curve, four songs of Article 1Line, conical section curve and Article 2 biquadratic curve;

(2) set up two-dimensional coordinate system, taking the line of Wind Tunnel Contraction entrance and exit central point as x axle, contraction section outletDirection be the positive direction of x axle, be y axle taking contraction section entrance perpendicular to the straight line of x axle, contraction section entrance is positioned at y axleIn positive axis, the intersection point of x axle and y axle is initial point O;

(3) calculate intermediate variable value, comprise length d, Article 2 biquadratic curve and the conical section of Article 2 biquadratic curveThe ordinate value R of intersection point⁺, Article 2 biquadratic curve and conical section the abscissa x of intersection point⁺, Article 1 biquadratic curve length bAnd the length c of conical section;

(4) determine cylindrical section curve y₁(x)=R₁，0≤x≤a；

(5) determine Article 1 biquadratic curve $y_2\left(x\right)=R_1-\frac{b\tan \mathrm{\θ}}{2}{\left(\frac{x-a}{b}\right)}^3(2-\frac{x-a}{b}),$ a≤x≤b；

(6) determine conical section curve $y_3\left(x\right)=R_1+(a+\frac{b}{2})\tan \mathrm{\θ}-x\tan \mathrm{\θ},$ a+b≤x≤a+b+c；

(7) determine Article 2 biquadratic curve $y_4\left(x\right)=\frac{{(L-x)}^2}{12R^{*}}[6-{\left(\frac{L-x}{d}\right)}^2]+R_2,$ a+b+c≤x≤L；

(8) determine described Wind Tunnel Contraction curve according to step (4)-step (7), by cylindrical section curve, Article 1 fourInferior curve, conical section curve and Article 2 biquadratic curve are connected successively, obtain described Wind Tunnel Contraction curve.

In described step (3), calculating intermediate variable value is specially:

(2.1) pass through formulaCalculate the length d of Article 2 biquadratic curve, wherein, R^*For contraction section goes outMouth radius of curvature, θ is angle of throat;

(2.2) pass through formulaCalculate the ordinate value R of Article 2 biquadratic curve and conical section intersection point⁺；

(2.3) by formula x⁺=L-d calculates the abscissa x of the intersection point of Article 2 biquadratic curve and conical section⁺, L is for shrinkingDuan Quanchang;

(2.4) pass through formulaCalculate the length b of Article 1 biquadratic curve, wherein a isCylindrical section length, a=0～0.1 × L, R₁For contraction section entrance section radius;

(2.5) pass through formulaCalculate the length c of conical section, wherein, intermediate variable

In the time that described Wind Tunnel Contraction is subsonic wind tunnel contraction section, outlet radius of curvature R^*For contraction section outlet radius R₂6～10 times; In the time that described Wind Tunnel Contraction is supersonic wind tunnel, outlet radius of curvature R^*Value is supersonic wind tunnel expansion segmentIn the radius of curvature at wind-tunnel venturi place.

Described angle of throat θ gets 15 °～35 °.

The present invention's beneficial effect is compared with prior art:

Definite method of a kind of Wind Tunnel Contraction curve provided by the invention, given contraction section entrance size, outlet size,The radius of curvature of contraction section length and contraction section outlet, can, from contraction section entrance, set gradually cylinder curve, firstThe mode of bar biquadratic curve, conic section, Article 2 biquadratic curve, obtains the curve of contraction section. Design according to the inventive methodContraction section curve, be applicable to subsonic wind tunnel, supersonic wind tunnel, whole curvature of curve is completely continuous, and entrance and exit placeCurvature consistent with the curvature of front and back parts, realize perfect connection. Curve front portion can not shunk very steep, and outlet does not also produce overshootPhenomenon, can overcome the deficiency of existing contraction section curve. Exit flow is uniformly distributed.

Brief description of the drawings

Fig. 1 is contraction section curve synoptic diagram of the present invention;

Fig. 2 is contraction section curve schematic diagram of the present invention;

Fig. 3 is the inventive method flow chart.

Detailed description of the invention

The inventive method is by arranging cylindrical section curve, Article 1 biquadratic curve, conical section curve and four songs of Article 2Line mode is obtained contraction section curve.

A definite method for Wind Tunnel Contraction curve, as shown in Figure 3, comprises the steps:

(1) Wind Tunnel Contraction appearance curve being divided into four parts, is respectively cylindrical section curve, four songs of Article 1Line, conical section curve and Article 2 biquadratic curve, as shown in Figure 1, in figure, 1 represents cylindrical section, 2 represent Article 1 biquadratic curveSection, 3 represent conical section, and 4 represent Article 2 biquadratic curve section, and 5 represent contraction section outlet.

(2) as shown in Figure 2, set up coordinate system, taking the line of contraction section entrance and exit central point as x axle, contraction section goes outMouthful direction be the positive direction of x axle, taking contraction section entrance A perpendicular to the straight line of x axle as y axle, entrance A is just being positioned at y axleOn semiaxis, the intersection point of x axle and y axle is initial point O,

(3) calculate intermediate variable value, be specially:

(3.1) pass through formulaCalculate the length d of Article 2 biquadratic curve, wherein, R^*For contraction section goes outMouth radius of curvature, when design subsonic wind tunnel contraction section, R^*For contraction section outlet radius R₂6～10 times, design is super/high ultrasonicWhen speed Wind Tunnel Contraction, R^*Value is the radius of curvature of supersonic speed expansion segment at venturi place. θ is angle of throat, gets 15 °～35 °;

(3.2) pass through formulaCalculate the intersection point of Article 2 biquadratic curve and conical section+vertical seatScale value R⁺；

(3.3) by formula x⁺=L-d calculate+abscissa x⁺；

(3.4) pass through formulaCalculate the length b of Article 1 biquadratic curve, wherein a isCylindrical section length, can suitably regulate and choose according to reality, a=0～0.1L, and L is contraction section total length;

(3.5) pass through formulaCalculate the length c of conical section, intermediate variable

(4) determine cylindrical section curvilinear coordinate, in the time of 0≤x≤a, by formula y₁(x)=R₁Calculate cylindrical section curvilinear coordinatey(x)；

(5) determine Article 1 biquadratic curve coordinate,, in the time of a≤x≤b, pass through formula $y_2\left(x\right)=R_1-\frac{b\tan \mathrm{\θ}}{2}{\left(\frac{x-a}{b}\right)}^3(2-\frac{x-a}{b})$ Calculate Article 1 biquadratic curve coordinate y (x);

(6) determine conical section curvilinear coordinate,, in the time of a+b≤x≤a+b+c, pass through formula $y_3\left(x\right)=R_1+(a+\frac{b}{2})\tan \mathrm{\θ}-x\tan \mathrm{\θ}$ Calculate conical section curvilinear coordinate y (x);

(6) determine Article 2 biquadratic curve coordinate,, in the time of a+b+c≤x≤L, pass through formula $y_4\left(x\right)=\frac{{(L-x)}^2}{12R^{*}}[6-{\left(\frac{L-x}{d}\right)}^2]+R_2$ Calculate Article 2 biquadratic curve coordinate y (x):

(7) determine described Wind Tunnel Contraction curve according to step (3)-step (6), by cylindrical section curve, Article 1 fourInferior curve, conical section curve and Article 2 biquadratic curve are connected successively, obtain described Wind Tunnel Contraction curve, for wind-tunnel is establishedHow timing designs contraction section appearance curve foundation and method is provided.

Claims (3)

1. a definite method for Wind Tunnel Contraction curve, is characterized in that: comprise the steps:

(1) Wind Tunnel Contraction appearance curve being divided into four parts, is respectively cylindrical section curve, Article 1 biquadratic curve, circleCone section curve and Article 2 biquadratic curve;

(2) set up two-dimensional coordinate system, taking the line of Wind Tunnel Contraction entrance and exit central point as x axle, the side of contraction section outletTo the positive direction that is x axle, be y axle taking contraction section entrance perpendicular to the straight line of x axle, contraction section entrance is positioned at just half of y axleOn axle, the intersection point of x axle and y axle is initial point O;

(3) calculate intermediate variable value, comprise the intersection point of length d, Article 2 biquadratic curve and the conical section of Article 2 biquadratic curveOrdinate value R⁺, Article 2 biquadratic curve and conical section the abscissa x of intersection point⁺, Article 1 biquadratic curve length b andThe length c of conical section;

Be specially:

(2.1) pass through formulaCalculate the length d of Article 2 biquadratic curve, wherein, R^*For contraction section outlet songRate radius, θ is angle of throat;

(2.2) pass through formulaCalculate the ordinate value R of Article 2 biquadratic curve and conical section intersection point⁺；R₂For contraction section goes out port radius;

(2.3) by formula x⁺=L-d calculates the abscissa x of the intersection point of Article 2 biquadratic curve and conical section⁺, L is that contraction section is completeLong;

(2.4) pass through formulaCalculate the length b of Article 1 biquadratic curve, wherein a is cylinderSegment length, a=0～0.1 × L, R₁For contraction section entrance section radius;

(2.5) pass through formulaCalculate the length c of conical section, wherein, intermediate variable

(4) determine cylindrical section curve y₁(x)＝R₁，0≤x≤a；

(5) determine Article 1 biquadratic curve $y_2\left(x\right)=R_1-\frac{btan\mathrm{\θ}}{2}{\left(\frac{x-a}{b}\right)}^3(2-\frac{x-a}{b}),a\≤x\≤b;$

(6) determine conical section curve $y_3\left(x\right)=R_1+(a+\frac{b}{2})tan\mathrm{\θ}-xtan\mathrm{\θ},a+b\≤x\≤a+b+c;$

(7) determine Article 2 biquadratic curve $y_4\left(x\right)=\frac{{(L-x)}^2}{12R^{*}}\[6-{\left(\frac{L-x}{d}\right)}^2\]+R_2,a+b+c\≤x\≤L;$

(8) determine described Wind Tunnel Contraction curve according to step (4)-step (7), by cylindrical section curve, four songs of Article 1Line, conical section curve and Article 2 biquadratic curve are connected successively, obtain described Wind Tunnel Contraction curve.

2. definite method of a kind of Wind Tunnel Contraction curve according to claim 1, is characterized in that: when described wind-tunnel is receivedWhen contracting section is subsonic wind tunnel contraction section, outlet radius of curvature R^*For contraction section outlet radius R₂6～10 times; When described wind-tunnelWhen contraction section is supersonic wind tunnel, outlet radius of curvature R^*Value is the curvature half of supersonic wind tunnel expansion segment at wind-tunnel venturi placeFootpath.

3. definite method of a kind of Wind Tunnel Contraction curve according to claim 1, is characterized in that: described angle of throat θGet 15 °～35 °.