# Aerospace How mass flow and pressure ratio is related in case of a Gas Turbine

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1. Jun 1, 2017

Hi,

As per my observation and experience, when we use evaporative cooler to cool the inlet air to the gas turbine, the compressor discharge pressure (i.e PCD or P3) rises. As, the temp. of the inlet air drops and the mass flow increases due to the increase in density, I believe the discharge pressure of the compressor also rises.

However, as per the performance characteristic curve of the compressor, the pressure ratio is inversely proportional to the mass flow.

Can please someone help me understand this

2. Jun 4, 2017

### John Dalton

The conservation of mass (continuity) tells us that the mass flow rate mdot through a tube is a constant and equal to the product of the density r, velocity V, and flow area A:

Eq #1:

mdot = r * V * A

3. Jun 5, 2017

I am interested in knowing that when the mass flow across the compressor rises what happen to the pressure ratio ?

4. Jun 5, 2017

### BvU

Could you provide a bit more context ? You seem to know what you are describing, but we see only loose fragments.

5. Jun 5, 2017

### John Dalton

(By giving mathematical evidences).

6. Jun 5, 2017