Pressure Drop in a Exhaust Pipe: Eddy Plate Mixer @ Different Q

[SCRcatman]

I have a device (static mixer) in an exhaust system and I only have the estimated DP from the manufacturer at one condition. The estimated DP is at a given exhaust flow, temp, velocity, etc which I provided them. I need to estimate the DP across this device at different engine loads (volumetric flows). I do not know anything about the physical device except that the flow is annular around an eddy plate mixer. I know everything (temp, flow velocity, MW, etc.) about the exhaust and piping. I am looking for help on how I can relate the known pressure drop across a device at one flow rate to a new DP at a lower flow rate (Q).

Still in design so not a system I can physically measure (test) anything in at his point.

Example:
Estimated DP from the manufacturer of the static mixer - 1.2 inWC @
Q1 - 8000 CFM @ 874F
IDpipe - 19.625 in

DP2 = ? @
Q2 - 5300 cfm @ 937F
IDpipe - 19.625 in

 

[RVAmeche]

You could use the square law to get a quick and dirty estimate. Since dP varies with flow, you can interpolate by:
Q = X*(dP)^1/2
Q1 = 0; dP2 = 0
Q2, dP2 = your data point
Solve for X
Plug in desired Q3 to calculate dP3

If density is significantly changing, I'd include density beneath dP inside the square root.
I'd ask the manufacturer to see if they could give you a plot or loss value, since it'll be more accurate that way.