Species Model – Inlet temperature

[sjohn]

I have created a single phase model of three gas jets flowing into a chamber with an outlet. Indential massflowrates and temperatures are specified at the inlets and a pressure is specified at the outlet.

The material is a mixture made of up of 13 species. The mass fraction of 8 species is zero because later I plan to introduce reactions and these 8 species are products of the reaction. So 5 species have non-zero mass fractions. The properties of the mixture were calculated as shown below:

How do I explain that the temperature of the gas jet in the central location is lower than the specified inlet temperature (~1400 C). In the figure below, two out of the three jets are shown. If this is due to cooling of the gas due to expansion, I imagine the temperature surrounding the jet would be lower. I don't see a similar effect if the fluid material is air (from Fluent database). I do have Diffusion energy source, Full multicompoent diffusion, and Thermal diffusion all turned on under the Species model.