Method for calculating arc line in mechanical blade of impeller

Abstract

The invention discloses a method for calculating an arc line in the mechanical blade of an impeller, comprising the following steps: selecting a point A on the back arc of the blade to obtain the normal line of the back arc at the point A and the crossing point C of the normal line and the inner arc; setting a circle O2 using a line segment AC as the diameter to obtain another crossing point D ofthe circle O2 and the inner arc; selecting a point of the CD end of the inner arc as the normal line of the inner arc, wherein the normal line is crossed with the line segment AC, and the crossing point can be determined to be a point of the mean camber line if the difference between the distance between the crossing point and the point A and the distance between the crossing point and the selected point on the inner arc is within the specified error range. The position of the tangential point of the inscribed circle and the inner arc is accurately limited on the CD curve of the inner arc by selecting a point A on the back arc as the tangential point of the inscribed circle and the inner arc so as to narrow down target area, save calculation time and be capable of guaranteeing iteration convergence, and the calculation method of the mean camber line is simple, convenient and quick, and has the advantages of high calculation precision and quick calculation speed.

Description

Technical field [0001] The invention relates to a blade of an impeller machine, in particular to a method for calculating the arc in the blade of the impeller machine. Background technique [0002] When predicting the performance of an impeller machine, it is usually necessary to know the parameters of the blade profile, such as geometric inlet angle, geometric outlet angle, maximum blade thickness and position, maximum deflection, chord length and other parameters, and to know these aerodynamic parameters of the blade , It is necessary to find the middle arc of the blade first, and the error of the middle arc is directly related to the accuracy of the whole machine performance prediction. In addition, in reverse engineering, the middle arc is an important basis for the discretization of the blade section line, which has a very important influence on the quality of the blade shape. Small errors in the middle arc may cause the final blade profile to be unsmooth and affect the aer...

AI Technical Summary

Problems solved by technology

However, the shortcomings of this calculation method are obvious. The method of calculating the intersection point of the circle and the profile line is not easy to converge, which makes the calculation time long due to the large number of iterations, and sometimes even fails to converge, resulting in no calculation results.

There are other algorithms that use approximate methods in calculations, which often cause relatively large errors and cannot meet the requirements of blade design and blade processing.

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