Calculating of k-epsilon

Question

I am examining a turbine stage with only one stator. I expect supersonic velocities and use the k-omega SST model with RANS 2- equation for the steady-state simulation. My medium is water vapor and I have an inlet temperature of about 1700 degrees.
Now I want to calculate the k-epsilon values and there is an online tool for that. Using the turbulence length scale, turbulence intensity and freestream velocity I can calculate the values I am looking for. According to the tool, the turbulence length at the inlet to the turbine stage can typically be defined as 5% of the channel height. The channel height should be the span of the blade I think, which is 0.024m for me. The freestream velocity is estimated to be about 1000m/s and the turbulence Intensity 5%. This gives me values for k: 3750 m^2 / s^2 and epsilon: 17222974 m^2 / s^3. Are the values not a little too high ? Am I doing something wrong ? Btw. I am using omnis

sriluta · Accepted Answer

Hey, sure. On the website cfd-online.com, in online tools/ Turbulence Properties, Conversions & Boundary Estimations its possible to calculate the values. I then clicked on the following: Turbulence variables (k, &epsilon;, &omega;) from turbulence intensity (Tu) , length-scale (TuL) and freestream velocity (U&infin;). So the turbulence intensity and length- scale are fixed values. I changed a little bit the freestream velocity, from 1000 m/s to 1500 m/s and used the ne values for k and epsilon to see if my results changed or not, and there was no difference in my result for different values of k and epsilon, therefore that's why I left the values as they are, so in my case it just fit.

Stats

Calculating of k-epsilon

Community Guidelines