I working in a combustion chamber similar to an engine one. During combustion I will need to add turbulence in a premixed flame using gaseous nitrogen with pressure up to 100 bar.
I checked the following types with respective problems:
-normal gasoline injector: the layout doesn't ensure leaks control
-nitrogen injector for moulding: high pressure but bad control of the injection rate
-CNG injector: really low pressure achievable (maximum 16 bar)
Does anyone know any supplier or research project which could have a suitable injector?
Thanks
Very likely your nozzle discharge will chocked. The mass flow rate is contant. But this approximatios is good if the openning time is much shorter than you miliseconds. Otherwise. Other than this is using transient calculatios and on situ calubratio.
Eugenio Rosa is correct; you need to be careful about choked flow and be aware of the relations of mass flow vs. flow velocity through whatever orifice you have downstream. You could charge a known length (volume) of tubing at a known temperature and pressure with your gas. From this, you can calculate the moles or mass of gas in the volume and, if you know your time differential (dt), you can calculate an average flow rate for that time. It may not be as sophisticated as a fancy Bronkhorst mass flow controller, but it would get the job done. This would be better if you had an upstream gas at the same pressure so that you can better manage the flow through your system - it works like a step tracer for ideal plug flow reactors.
We have used automotive high pressure gasoline direct injection fuel injectors to inject gases into pressure vessels. If you are not using them continuously for many hours per day, over many weeks they will maintain their flow rate. That is they do not seem to wear the pintle and seat of the injector rapidly, even though it is injecting a dry gas, instead of a liquid fuel.
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