Why water injection inside combustion chamber increasing temperature at the outlet?

johnleo · February 17, 2021, 19:07

Hello good people!

I am doing simulation in a gas turbine combustor where I am directly injecting water droplets to reduce the overall temperature of the domain as well as the outlet temperature. But when I am using nonpremixed combustion model the maximum and the average temperature at the outlet is always increasing. But when using the EDM model it's decreasing accordingly. What can be the cause behind this behavior? If you can give me an idea it would be really helpful.

Thank you.

aerosayan · February 18, 2021, 05:15

Disclaimer : Not an expert.

If the water injection causes the combustion to move closer to the outlet, i.e by preventing proper combustion -> due to improper fuel atomization + evaporation -> due to reduction in combustion chamber temperature -> due to addition of cold water and the energy wasted in evaporating the cold water, the temperature at the outlet *may* increase.

My *beginner level* guess is that the fuel couldn't atomize + evaporate correctly in the combustion region, but caught on fire as the incomplete combustion products were leaving out of the combustion chamber.

Don't know if it's the case for you, but it's just a guess.

johnleo · February 18, 2021, 20:21

Thank you very much for suggesting the probable reasons. However, I am still confused why the EDM model not showing any increments like the nonpremixed model. Anyways, thanks again for the time.

February 17, 2021, 19:07	Why water injection inside combustion chamber increasing temperature at the outlet?	#1
johnleo New Member Pritam Dey Join Date: Apr 2020 Posts: 9 Rep Power: 6	Hello good people! I am doing simulation in a gas turbine combustor where I am directly injecting water droplets to reduce the overall temperature of the domain as well as the outlet temperature. But when I am using nonpremixed combustion model the maximum and the average temperature at the outlet is always increasing. But when using the EDM model it's decreasing accordingly. What can be the cause behind this behavior? If you can give me an idea it would be really helpful. Thank you.

February 18, 2021, 05:15		#2
aerosayan Senior Member Sayan Bhattacharjee Join Date: Mar 2020 Posts: 495 Rep Power: 8	Disclaimer : Not an expert. If the water injection causes the combustion to move closer to the outlet, i.e by preventing proper combustion -> due to improper fuel atomization + evaporation -> due to reduction in combustion chamber temperature -> due to addition of cold water and the energy wasted in evaporating the cold water, the temperature at the outlet may increase. My beginner level guess is that the fuel couldn't atomize + evaporate correctly in the combustion region, but caught on fire as the incomplete combustion products were leaving out of the combustion chamber. Don't know if it's the case for you, but it's just a guess. johnleo likes this.

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February 18, 2021, 20:21		#3
johnleo New Member Pritam Dey Join Date: Apr 2020 Posts: 9 Rep Power: 6	Thank you very much for suggesting the probable reasons. However, I am still confused why the EDM model not showing any increments like the nonpremixed model. Anyways, thanks again for the time.