- posted
8 years ago

purposes, P = f(Q,V), where P is pressure, Q flow and V a vane position. For

fixed V, the P-Q relationship is well behaved, and monotonic (avoiding the

surge region) within the domain of interest, essentially a segment of a

parabola or cubic. As V varies, the curves shift, rescale and rotate

slightly.

I can generate a table of spot values of the variables, but the regression

functions I've come across such as the Excel linest function, seems to be

confined to linear functions. Can anyone suggest a tool that will faciliate

deriving a polynomial (or other form) equation to model my datasets? The

alternative is the very fiddly process of manually working out variable

coefficients for the constant-V curves that model them as they shift around.

Being a real engineering problem, I'm hoping for a quick and easy solution,

precision isn't essential. otoo +/- 10% would do. TIA