Abstract
The fan P-Q third order polynomial characteristic curve is used in an air flow network model, but the practical difficulty is to prepare the coefficients because of the almost infinite variations for fan capacity and because of the difficult extrapolation required for the curve to implement the least squares method owing to the relatively small curve range that can be referenced in manufacturer supply materials. The present paper proposes a theory and an algorithm to automatically generate the coefficients of the P-Q characteristic curve when only the design flow rate and total pressure are given. The theory is based on a similar transformation of the curve concerning the origin of the P-Q coordinates and expansion or contraction along the Q coordinate.
