CN102996504B - Centrifugal impeller flow passage design method for controlling slope distribution - Google Patents

Abstract

The invention belongs to fluid mechanical design modeling methods and in particular relates to a centrifugal impeller flow passage design method for controlling slope distribution. Meridional flow passage design steps of a centrifugal impeller comprise the following steps: carrying out parameterized formation by controlling distribution of slopes of a wheel cap line and a wheel hub line in the axial direction; and then rotating an obtained wheel cap curve and a wheel hub curve with 360 degrees around a rotation shaft to obtain a wheel cap face and a wheel hub face. Appropriate slope distribution regularity can be flexibly selected to control distribution of flow load of the centrifugal impeller in the axial direction according to flow acting situations of the centrifugal impeller by controlling the slopes of the flow passage curves, and the acting efficiency and the stable work boundary of the centrifugal impeller are improved. The centrifugal impeller flow passage design method can be widely applied to flow design of various centrifugal and diagonal flow turbomachinery.

Description

A Centrifugal Impeller Flow Path Design Method Controlling the Slope Distribution

technical field

The invention belongs to a fluid machine design modeling method, in particular to a centrifugal impeller flow path design method for controlling slope distribution.

Background technique

Centrifugal impeller machinery is a core component of jet aeroengines, and is widely used in the field of functional conversion of various fluid compressions or fluid expansions. The design of the meridian channel of the centrifugal impeller machinery has a great influence on the performance of the centrifugal impeller machinery. However, there is no clear design criterion for the design of the meridian flow channel. Generally, it depends on the experience of the designer, and the design is relatively subjective. At present, the conventional design method of meridian runner profile is generally formed by connecting arcs and straight lines. This design method is easy to cause flow loss and reduce the work efficiency of centrifugal impeller machinery.

Contents of the invention

The invention proposes a centrifugal impeller channel design method for controlling slope distribution, which has good flow performance and can improve the functional work efficiency of centrifugal impeller machinery.

The technical scheme adopted in the present invention is:

The meridian channel of the centrifugal impeller is enveloped by the wheel cover line, hub line, inlet line, and outlet line. The design steps are:

(1) Parametrically formed by controlling the distribution of the slope of the wheel cover line and the hub line in the axial direction; the slope distribution of the wheel cover line and the hub line adopts the cubic polynomial S(x)=Ax ³ +Bx ² +Cx +D to determine, where S is the slope of the curve, x is the length of the dimensionless flow direction, and A, B, C, and D are dimensionless coefficients. The specific values are shown in the following table:

A B C D. wheel cover line 3e-4 4.0e-2 0.42e-1 4.76 hub line 3e-4 5.1e-2 1.46 6.37

;

The specific steps to determine the wheel cover line and hub line are:

(101) According to the one-dimensional flow calculation method, respectively determine the positions of the four endpoints of the wheel cover line and the hub line;

(102) Divide the wheel cover line into n (50≤n≤200) segments, determine the axial coordinates of n-1 points except the two ends, according to the slope k of the first point and the coordinates of the point ( Z ₁ , R ₁ ), determine the coordinates of the second point (Z ₂ , R ₂ ); then use the slope k of the second point and the coordinates of this point to determine the coordinates of the third point (Z ₃ , R ₃ ); By analogy, the coordinates of all points of the wheel cover line are obtained;

(103) Fit n+1 points on the obtained wheel cover line with a smooth curve to obtain a smooth wheel cover curve;

(104) Obtain the hub curve by adopting the methods of steps (102) and (103);

(2) The wheel cover curve and hub curve obtained in step (1) are rotated 360° around the rotation axis to obtain the wheel cover surface and hub surface.

The present invention has following beneficial effect:

By controlling the slope of the flow channel curve, the appropriate slope distribution law can be flexibly selected according to the flow and work of the centrifugal impeller, and the distribution of the flow load of the centrifugal impeller in the axial direction can be controlled, which improves the work efficiency and the stable working boundary of the centrifugal impeller, and can be widely used It is applied to the flow design of various centrifugal and oblique flow impeller machines.

Description of drawings

Fig. 1 is a schematic diagram of the structure principle of the present invention.

Fig. 2 is a schematic diagram of the meridian flow channel in Fig. 1 .

Figure 3 is a graph of a typical slope profile for an implementation of the present invention.

Labels in the figure:

1-Wheel cover line; 2-Hub line; 3-Inlet line; 4-Exit line.

Detailed ways

The present invention provides a centrifugal impeller flow path design method for controlling slope distribution. The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The axial longitudinal section of centrifugal impeller machinery is generally called meridian flow channel. The meridian flow channel is enveloped by the wheel cover line 1, the hub line 2, the inlet line 3 and the outlet line 4, as shown in Fig. 1 and Fig. 2 .

The design steps of the meridian flow channel are:

(1) The slope distribution of the wheel cover line and the hub line is determined by the cubic polynomial S(x)=Ax ³ +Bx ² +Cx+D, where S is the slope of the curve, x is the dimensionless flow length, A, B , C, and D are dimensionless coefficients, and the specific values are shown in the following table:

A B C D. wheel cover line 3e-4 4.0e-2 0.42e-1 4.76 hub line 3e-4 5.1e-2 1.46 6.37

The specific steps to determine the wheel cover line and hub line are:

(101) According to the one-dimensional flow calculation, determine the coordinates of the first and last endpoints of the wheel cover line as (-75,78.5) (-8.4,118), and the coordinates of the first and last endpoints of the hub line as (-75,30) (0,118);

(102) Divide the wheel cover line into 100 segments, and determine the curvature distribution law of a total of 101 discrete points according to the formula in step (1), as shown in the following table:

m% S 0 2.32822752 1.081193125 2.684830529 2.158423216 3.052522752 3.231690273 3.431304189 4.302531701 3.821744421 5.370643162 4.223781636 6.434353142 4.637521399 7.493103413 5.064098509 8.548594601 5.504275681 9.598761667 5.957385241

10.64259234 6.424558357 11.68162113 6.90694199 12.7149665 7.404196413 13.74096037 7.916498385 14.75987996 8.445282513 15.7750857 8.992472579 16.78168811 9.555828644 17.77826145 10.13622719 18.77284031 10.73894675 19.75956937 11.36083407 20.73470078 12.00065915 21.70652987 12.66517963 22.68583208 13.3630336 23.65146125 14.08025866 24.6019665 14.81672705 25.53737196 15.57258196 26.45749724 16.3476886 27.36147888 17.14132595 28.25352674 17.9574741 29.13529651 18.79829935 29.99991337 19.65719931 30.84714997 20.53264277 31.6970085 21.44647939 32.52933638 22.37828312 33.34397638 23.32532585 34.1556733 24.30460663 34.96250196 25.31572893 35.75124714 26.3412808 36.52547077 27.38215321 37.31243403 28.4771139 38.08141862 29.58511401 38.83476969 30.7036116 39.59375993 31.86377058 40.34926271 33.05391233 41.09005012 34.25336808 41.82388345 35.46919189 42.57060858 36.7360406 43.30440203 38.01054488 44.02879026 39.29034799 44.76325115 40.60891827 45.4956161 41.94554822 46.22123034 43.2858758 46.94775593 44.63791383 47.68331216 46.01715949 48.41532489 47.39829165

49.14793261 48.77911285 49.88908244 50.17321563 50.6329808 51.56957463 51.38159653 52.96339465 52.13671281 54.35230083 52.89793139 55.73561284 53.66755874 57.11429406 54.45013836 58.48557459 55.23483435 59.83023415 56.03177849 61.16597678 56.84604016 62.49105911 57.669658 63.78852295 58.50122558 65.05770015 59.35293003 66.3136157 60.22802514 67.55102947 61.10222131 68.73739341 61.99970614 69.90696689 62.92383305 71.0549536 63.86078224 72.16253241 64.81380023 73.23572679 65.79407145 74.2843528 66.80078791 75.30176227 67.82096445 76.27619754 68.86896438 77.22216587 69.9442864 78.13549514 71.04565632 79.0143245 72.17364204 79.85923184 73.32709666 80.66920419 74.50916573 81.44580417 75.73116451 82.1950839 76.97682679 82.90654766 78.24197995 83.58050177 79.56403717 84.23515278 80.91612755 84.85454996 82.28494047 85.43584244 83.69361042 85.9904904 85.16644159 86.5245884 86.65374539 87.01940575 88.15135633 87.47946666 89.74955535 87.92964662 91.36933979 88.34395631 92.99704241 88.7245832 94.68622279 89.08560158 96.45034258 89.42611574 98.22160165 89.73091521 100 90

(103) Divide the wheel cover line into 100 segments, determine the axial coordinates of the middle 99 points except the two ends, and determine according to the slope k of the first point and the coordinates of this point (Z ₁ , R ₁ ). The coordinates of the second point (Z ₂ , R ₂ ); then use the slope k of the second point and the coordinates of this point to determine the coordinates of the third point (Z ₃ , R ₃ ); and so on, to get the wheel cover line The coordinates of all points; the following table lists the coordinates of the first 15 points, and the remaining points are obtained by analogy.

Z R -75.0 78 -72.0408 77.9949 -69.0817 77.9924 -66.1225 77.9898 -63.1633 77.9873 -60.2042 77.9847 -57.245 77.9821 -54.2858 77.9796 -51.3266 77.977 -48.3675 77.9745 -45.4083 77.9719 -42.45 78.0193 -39.5072 78.3191 -36.6048 78.8906 -33.7679 79.7287

(104) Fit 101 points on the obtained wheel cover line with a smooth curve to obtain a smooth wheel cover curve;

(105) Obtain the hub curve by adopting the method of steps (102)-(104);

(2) The wheel cover curve and hub curve obtained in step (1) are rotated 360° around the rotation axis to obtain the wheel cover surface and hub surface.

Claims (1)

1. A centrifugal impeller flow path design method for controlling the slope distribution, the meridional flow path of this centrifugal impeller is enveloped by wheel cover line, hub line, inlet line, and outlet line, and it is characterized in that the design steps are: (1) Parametrically formed by controlling the distribution of the slope of the wheel cover line and the hub line in the axial direction; the slope distribution of the wheel cover line and the hub line adopts the cubic polynomial S(m)=Ax ³ +Bx ² +Cx +D to determine, where S is the slope of the curve, x is the length of the dimensionless flow direction, A, B, C, and D are dimensionless coefficients, and the specific values are as follows: A B C D. wheel cover line 3e-4 4.0e-2 0.42e-1 4.76 hub line 3e-4 5.1e-2 1.46 6.37 ; The specific steps to determine the wheel cover line and hub line are: (101) According to the one-dimensional flow calculation method, respectively determine the positions of the four endpoints of the wheel cover line and the hub line; (102) Divide the wheel cover line into n (50≤n≤200) segments, determine the axial coordinates of n-1 points except the two ends, according to the slope k of the first point and the coordinates of the point ( Z ₁ , R ₁ ), determine the coordinates of the second point (Z ₂ , R ₂ ); then use the slope k of the second point and the coordinates of this point to determine the coordinates of the third point (Z ₃ , R ₃ ); By analogy, the coordinates of all points of the wheel cover line are obtained; (103) Fit n+1 points on the obtained wheel cover line with a smooth curve to obtain a smooth wheel cover curve; (104) Obtain the hub curve by adopting the methods of steps (102) and (103); (2) The wheel cover curve and hub curve obtained in step (1) are rotated 360° around the rotation axis to obtain the wheel cover surface and hub surface.