# hel (turbulent viscosity ratio limited) for supersonic combustion problem

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 March 11, 2010, 06:24 hel (turbulent viscosity ratio limited) for supersonic combustion problem #1 New Member   Omar Join Date: Mar 2010 Posts: 3 Rep Power: 16 hey all, Problem description: I'm trying to model the supersonic flow in a 2D scramjet combustor. I used a configuration as a mid-injection of H2 at sonic conditions (M=1) and a Mach 2 freestream conditions. The inlet inputs can be found at the end. I used the k-epsilon turbulence model since the turbulent kinetic energy and dissipation rate are given in the experiment ( where I got the information of the inlet from ). I used a non-premixed combustion with specifying all the data and calculating the PDF table for the present problem. The mesh is really fine ( I think fine enough ) and do not think the problem relies there, so I think my turbulent BCs are somewhat wrong. I also specified the exit plane as a pressure outlet, but got a reversed flow there too. There are many issues with the simulation so if someone has good ideas of a way to get rid of the errors please let me know. Many thanks and please find the inputs below. So my questions now are: 1- How to get rid of the turbulent viscosity ratio? 2- What is the best turbulence model for the imposed problem? 3- Shall I change the turbulent BCs to something like Hydraulic diameter and intensity ? 4- How to get rid of the reversed flow? I'm still not clear of how to specify the backflow conditions. 5- Shall I increase the limit of the viscosity ratio ? or is that unrealistic? 6- How can I calculate the mean mixture fraction of both fuel and air? The user manual does not provide a formula for this. I need some help please. Thanks to all. Air / Hydrogen Mach number 2 / 1 u m/s) 730 / 1200 T (K) 340 / 250 P (10^5 Pa) 1 / 1 density (kg/m^3) 1.002 / 0.097 mass fraction (O2) 0.232 / 0 mass fraction (N2) 0.736 / 0 mass fraction (H2O) 0.032/ 0 mass fraction (H2) 0 / 1 k (m^2/s^2) 10 / 2400 epsilon (m^2/s^3) 650 / 10^8

 July 20, 2010, 04:41 Hi Omar #2 New Member   C T Join Date: Jul 2010 Posts: 7 Rep Power: 15 Just curious if you have got any results as I too am doing something similar CPT

 September 5, 2012, 11:04 Which user manual u referring to #3 New Member   Peter P Join Date: Sep 2012 Location: India Posts: 1 Rep Power: 0 Just out of curiosity which user manual u wre referring to?