METHOD FOR CALCULATING CHARACTERISTIC CURVE OF CENTRIFUGAL FLUID MACHINE BY COMPUTER

摘要

Method for calculating one of the characteristic curves of a centrifugal fluid machine, such as a Q-H characteristic curve, a Q-E characteristic curve, and a Q-NPSH characteristic curve by using a computer. A characteristic curve Y3 passing another point (x 3, y 3) and expressed by a high-degree expression Y3-=b 1+b 2x+b 3x 2+...+b nx (n-1) is defined by using two desired characteristic curves Y1, Y2 of a centrifugal fluid machine expressed by high-degree expressions Y1=a 1 1+a 1 2x+a+1+3x 2+...+a 1 nx (n-1) and Y2=a 2 1+a 2 2x+a 2 3x 2+...+a 2 nx (n-1). The point (x 3, y 3) is not on the two characteristic curves Y1, Y2. The characteristic curve Y3 is defined using an expression b n={a 1 nkh 1(1/kq 1) (n-1)x(y3-y2)/(y1-y2)}+{a2nkh2(1/kq2)(n-1)x(y1-y3)/(y1-y2)} by selecting a predetermined point (x 1, y 1) on the characteristic curve Y1 and a predetermined point (x 2, y 2) on the characteristic curve Y2 corresponding to the point (x 1, y 1).