# Enthalpy at the throat of the nozzle

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1. Feb 24, 2016

### Naav_Gothalla

Hi, This is my first post in this forum
I have a total enthalpy ht=3000 kj/kg with velocity at inlet v1=20 ms-1, Speed of sound a1=562.5 ms-1 and outlet pressure P2 = 1 bar
With the formula ht=h*+(a*2/2) how do i calculate actual value at throat h* ?

NOTE: (by trial and error)
• I can take any guesses for enthalpy at throat and i start by considering h*=2800 Kj/kg
• Total enthalpy and entropy remains constant at 3000 Kj/kg and Entropy with 6.5 Kj/K
• ht-htinlet != 0 i.e Δ=0

2. Feb 29, 2016

### Greg Bernhardt

Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?

3. Mar 2, 2016

Have you tried anything yourself yet?

4. Mar 3, 2016

### Naav_Gothalla

Yes , Sir I found the result.
I guessed enthalpy at throat and i start by considering h*=2800 Kj/kg later on i find the speed of air(c*) = velocity of sound at throat(v*) for Mach 1. Furthermore, i calculate actual enthalpy at throat using the formula (h*=ht-c*2/2). I use a solver in excel such that Δh=(ht-h*) should be equal to zero there by finding the actual enthalpy at the throat. Next I calculate pressure and temperature which are a function of enthalpy and entropy.

5. Mar 3, 2016