Yet another first timer with first timer questions.....
Nov 1, 2019 14:20:13 GMT -5
racket likes this
Post by turboron on Nov 1, 2019 14:20:13 GMT -5
John, in trying to understand the origin of the a/R scroll parameter I finally found some information in one of my files. A simple ideal model of volute flow is the basis for a/R. It is based on constant angular momentum, or free-vortex equation which is rV= Constant = K and the continuity equation m = density*Area*V for any azimuth angle theta.
m sub theta = m(1-theta/2(3.14)) where m is the total mass flow and theta is in radians. Therefore,
a/R = (m/density)*(1/K)*(1-theta/(2*3.14))
Another refence defined K as + 2*3.14*(impeller radius)^2*(tip speed).
I made some numbers using these equations and compared them to the Garrett data for new turbine housings. The equaions give somewhat reasonable answer is you consider the tip speed to be in radians/sec.
Food for thought,
Thanks, Ron
m sub theta = m(1-theta/2(3.14)) where m is the total mass flow and theta is in radians. Therefore,
a/R = (m/density)*(1/K)*(1-theta/(2*3.14))
Another refence defined K as + 2*3.14*(impeller radius)^2*(tip speed).
I made some numbers using these equations and compared them to the Garrett data for new turbine housings. The equaions give somewhat reasonable answer is you consider the tip speed to be in radians/sec.
Food for thought,
Thanks, Ron