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

• Austin_Tx_Rockets
In summary, the discharge coefficient is a ratio that can be experimentally measured and is dependent on the shape of the orifice and the fluid's Reynolds number. While an orifice with a rounded inlet will have a coefficient close to 1.0, an orifice with a square edge inlet will have a coefficient around 0.61 at high Reynolds numbers. The discharge coefficient is unique to each fluid and is affected by the fluid's density.
Austin_Tx_Rockets
TL;DR Summary
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?

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.

gmax137 and Lnewqban

## 1. Does the discharge coefficient of an injector depend on the fluid?

Yes, the discharge coefficient of an injector is highly dependent on the fluid being injected. This is because different fluids have different viscosities, densities, and surface tensions, which can affect the flow and behavior of the fluid through the injector.

## 2. How does the viscosity of a fluid affect the discharge coefficient of an injector?

The viscosity of a fluid plays a significant role in determining the discharge coefficient of an injector. Higher viscosity fluids tend to have a lower discharge coefficient, as they are more resistant to flow and require more energy to pass through the injector.

## 3. Is the discharge coefficient of an injector affected by the density of the fluid?

Yes, the density of the fluid also has an impact on the discharge coefficient of an injector. In general, higher density fluids will have a higher discharge coefficient, as they have more mass and energy to push through the injector.

## 4. What is the role of surface tension in the discharge coefficient of an injector?

Surface tension is another important factor that can affect the discharge coefficient of an injector. Higher surface tension fluids tend to have a lower discharge coefficient, as the cohesive forces between the molecules make it more difficult for the fluid to flow through the injector.

## 5. Are there any other factors that can influence the discharge coefficient of an injector?

Yes, there are several other factors that can impact the discharge coefficient of an injector, including the geometry and design of the injector, the pressure and temperature of the fluid, and the presence of any impurities or contaminants in the fluid. These factors should be carefully considered when studying the discharge coefficient of an injector.

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