i am currently building a project consisting of water injection using GDI Injector for water injection into a 4 cylinder diesel engine. the calculation i search from the internet does not explain on how to measure flow(how much water is injected i mean) to the engine. i will be running Denso E7T05072 at 3-5 bar of pressure depending on volume that i need to do testing.
Hello
Don't forget to start to a good comprehension of your problem before trying to find a solution on internet.
So the first is to know the ratio of fuel and water : OK not easy
So the solution is what does water do : globally cooling the gas
So you can calculate how much water you need per cycle so to have a final temperature compatible with autoignition delay
But to my experience I would say the ratio Water/Fuel should be less than 30%
So as I guess you know the fuel flow, you are able to calculate the water flow and the water flow per cylinder and per cycle;
What to you mean by GDI : gasoline direct injection ?
After that you look at the characteristics of your gasoline injectors :don't forget you put water in an injector for gasoline.
What is the principle of this injector ? is it compatible with water ?
If so you obtain the amount of water per cycle and per injector so you have to adapt the timing of opening and closing the injector at each cycle if injector is in the combustion chamber. If your injector is inth inlet pipe (i guess it is the case) it is the same.
You have to compare the characteristics with gasoline : the flow of water and gasoline could be different due to viscosity : you have to make a comparative test with one injector in free air between water and gasoline this is the best method.
I assume that you will use seperate unjectors for fuel abd water.
You just need to calibrate the injectors for different injection durations and pressure. Just keep the pressure constant and start to increase injection duration and measure the injected water via a scale. However 3 to 5 bat is very low for water inkection in late compression stroke. Do you wantt to inject it in intake stroke.
The question is not clear in the objective. Why do want to measure the flow rate/mass flow of the water?
Is it for calibrating how much water must be injected? Or is it that you already have it, and want to simply "measure" the water injected per cycle or per anything?
I assume its the latter, as calibrating the water injection would require a method to "measure" it first.
You know the injection pressure. (If you are not keeping it constant, measure it real time with a sensor), you know the orifice opening area. Implement the fluid dynamics principles and estimate the velocity head of the water flow through the injector orifice. Multiplying this velocity with the orifice area gives you volume flow rate.
You know the time for which the injector is held open. Integrate the flow rate in vol/unit time to obtain the entire flow. Multiply it by the density of the water if you need the mass flow per cycle.
Hope I didn't mess up with anything here :)
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