Need help for loss coefficient of elbow diffuser

Pete

Hi pals,

I'm working on the 90 deg elbow diffuser(inlet circular cross section & outlet rectangular cross section). The fluid is air at 25 deg c, 1 atm. Design inlet velocity is about 20m/s. Inlet to Outlet area ratio is 1:5.

Can anyone kind enough to advise me on how to estimate the pressure loss coefficent for this diffuser so that I can use it to get a realistic static pressure for the outlet boundary condition? Please let me know if you have any rough idea about the value of this loss coefficient.

Please help if you can.... Any ideas will be appreciated.

Thanks,Pete