work sheet
That is an interesting work sheet on the effects of WI, but you need to read the cautions about the model. I did a lot of playing with it and at reasonable amounts of injectant, it seems to give very good information.
It does not do any "bounds checking". If you put absurdly high amounts of water in, it while happily compute the cooling from total evaporation even though the amount of water is far beyond what is necessary to reach 100% humiditiy. Sometimes giving unrealistic air charge temps as a result.
So like any tool its no better than the base assumptions of the model. It does however, clearly indicate the basis for the assumption that post intercooler injection is the best "from the perspective of intake air cooling per gram of water injected".
It has no way of accounting for things like the change in timing of the pressure peak in the cylinder with different amounts of water and how that would effect the power output of a specific engine design.
The pre-turbo injection totally discounts any changes in the turbocharger compressor effeciency and any secondary feedbacks like, higher mass flow, lower turbo discharge temp, or lower exhaust gas back pressure that might result from that increase in effeciency.
Of course all those changes would be turbo type specific and would require a ton of code to cover all the popular turbochargers.
Larry
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