CN103016398B - Centrifugal impeller flow passage design method for controlling curvature distribution - Google Patents

Abstract

The invention belongs to a fluid mechanical design modeling method and particularly relates to a centrifugal impeller flow passage design method for controlling the curvature distribution. A meridional flow passage of a centrifugal impeller comprises the following design steps that the parametric forming is realized through controlling the axial distribution of the curvature of a wheel cover line and a wheel hub line; and then, an obtained wheel cover and an obtained wheel hub curve rotate for 360 degrees around a rotating shaft, and a wheel cover surface and a wheel hub surface are obtained. The design method has the advantages that the proper curvature distribution rule can be flexibly selected according to the flowing work applying condition of the centrifugal impeller through controlling the curvature of the flow passage curves, the work apply efficiency and the stable work boundary of the centrifugal impeller are improved, and the design method can be widely applied to various kinds of centrifugal and inclined flow type impeller mechanical flowing designs.

Description

A Design Method of Centrifugal Impeller Flow Channel by Controlling Curvature 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 curvature 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 wheel cover line and hub line 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 purpose of the present invention is to provide a centrifugal impeller channel design method that controls the curvature distribution, 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 curvature of the wheel cover line and the hub line in the axial direction; the curvature distribution law of the wheel cover line and the hub line is determined by the following formula:

Among them, C(m) is the curvature of the wheel cover line or the hub line, m is the dimensionless length of the wheel cover line or the wheel hub line; μ is the dimensionless position of the flow direction where the maximum curvature is located, and the preferred value of μ is 0.4 to 0.6; A is the dimensionless magnitude of the curvature of the crown line or hub line, and Where _r2 is the outlet radius of the centrifugal impeller;

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

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

(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 curvature 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 curvature 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) adopt the method of step (102) and (103), obtain hub curve;

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

The maximum curvature radius amplitude A of the hub line is 0.3-0.8 times of the maximum curvature of the wheel cover line.

The present invention has following beneficial effect:

By controlling the curvature of the flow path curve, the appropriate curvature 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 curvature 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 channel design method for controlling curvature distribution. The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

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) According to the formula To determine the curvature distribution curve of the wheel cover line, take μ=0.5, A=0.03, m in the interval [0,1], and e be the natural constant 2.718, so the distribution curve of C obtained is shown in figure 3 as the wheel cover curvature.

(101) Take n=100 points on the curvature distribution line as the curvature values required for determining the curve points in the next step, as shown in the table below.

(102) According to the one-dimensional flow calculation method, 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);

(103) Divide the wheel cover line into 100 segments, determine the axial coordinates of 99 points except the two ends, and determine the first point according to the curvature C of the first point and the coordinates (Z ₁ , R ₁ ) of the point The coordinates of the second point (Z ₂ , R ₂ ); then use the curvature C of the second point and the coordinates of this point to determine the coordinates of the third point (Z ₃ , R ₃ ); by analogy, all the wheel cover lines can be obtained the coordinates of the point;

(104) Fit the 101 points on the wheel cover line in the above table with a smooth curve to obtain a smooth wheel cover curve, as shown in Figure 2;

(105) adopt the method for step (102)-(104), obtain hub curve, as shown in Figure 2;

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

Claims (2)

1. A centrifugal impeller flow channel design method for controlling curvature distribution, the meridional flow channel of this centrifugal impeller is enveloped by wheel cover line, wheel hub line, inlet line, outlet line, it is characterized in that, the design steps are: (1) Parametrically formed by controlling the distribution of the curvature of the wheel cover line and the hub line in the axial direction; the curvature distribution law of the wheel cover line and the hub line is determined by the following formula: Among them, C(m) is the curvature of the wheel cover line or the wheel hub line, m is the dimensionless length of the wheel cover line or the wheel hub line; μ is the percentage value of the flow direction position where the maximum curvature is located, and the value range of μ is 0.4 to 0.6; A is the dimensionless magnitude of the curvature of the crown line or hub line, and Where _r2 is the outlet radius of the centrifugal impeller; The specific steps to determine the wheel cover line and hub line are: (101) Determine the positions of the four endpoints of the wheel cover line and the hub line respectively according to the one-dimensional flow calculation method; (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 curvature C(m) of the first point and the point coordinates (Z ₁ , R ₁ ), determine the coordinates of the second point (Z ₂ , R ₂ ); then use the curvature C(m) 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 on 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 line; (104) adopt the method of step (102) and (103), obtain hub line; (2) Rotate the wheel cover wire and hub wire obtained in step (1) by 360° around the rotation axis to obtain the wheel cover surface and the hub surface. 2. A centrifugal impeller runner design method for controlling curvature distribution according to claim 1, characterized in that the maximum curvature radius of the hub line is 0.3-0.8 times the maximum curvature value of the wheel cover line.