RajuMath
posted this
27 February 2019

- Last edited 27 February 2019
A nozzle with diameter 50mm is connected with a lance with diameter 200mm. Given that, gas flow rate 2.5 kg/s through the lance with 5 nozzles. As I am considering 1 nozzle, for 1 nozzle gas flow rate is 2.5 kg/s /5 =0.5kg/s. Now I am calculating the velocity for lance inlet from mass flow rate using

m_dot=rho*A*V; rho=1.138 kg/m3 gives V=0.5/(1.138*0.00785)=55.97m/s.

The same mass will flow through the nozzle exit. If I calculate the velocity at the nozzle exit

m_dot=rho*A*V; rho=1.138 kg/m3 gives V=0.5/(1.138*0.0019)=231.24m/s

In my simulation, I am using incompressible flow and velocity inlet boundary condition for 2D planner case. After converging, I am getting the nozzle exit velocity around 70 m/s.

What is the reason of this difference? Are there anything wrong in my above calculation?