Does the discharge coefficient of an injector depend on the fluid?

[Austin_Tx_Rockets]

TL;DR

If one were to experimentally measure the discharge coefficient using water, would this value be constant for all incompressible fluids?

The discharge coefficient is the ratio of the actual discharge to the ideal discharge and can be measured experimentally. If one were to experimentally measure the discharge coefficient using water, would this value be constant for all incompressible fluids?

What does the discharge coefficient depend on, and is it unique to every fluid?

 

[jrmichler]

The discharge coefficient is a function of the shape of the orifice and the fluid Reynolds number. An orifice with rounded inlet will have a discharge coefficient approaching 1.0, an orifice with a perfect square edge inlet will have the coefficient approximately 0.61 at high Reynolds numbers. Good search terms to learn more are orifice discharge coefficient and reynolds number. The image below shows the relationship between the discharge coefficient of a square edge orifice with the Reynolds number:

The discharge coefficient of a specific orifice is unique to the exact shape of the orifice and the Reynolds number.

 

[Lnewqban]

Welcome, @Austin_Tx_Rockets !

According to these articles, it depends on fluid density at least:

https://en.m.wikipedia.org/wiki/Discharge_coefficient

https://en.m.wikipedia.org/wiki/Flow_coefficient

Unless the tested fluid behaves like water, the value of your discharge coefficient should be different.