I have come up with an idea for a new simple jet engine. It will use an injector to "pump" in the fuel, in order to reduce the number of parts and wear on movable parts. However depending on the conditons under which the engine runs, the fuel entering the diffuser part of the injector may either be a liquide or a mix of liquid and gas (wet vapor). If it is liquid Bernouillis equation can be used to determine the stagnation pressure, if it is entirely gazious the normal isentropic nozzle theory can be used.
But I cannot figure out what to do if it is a wet vapor. I do not think using a hybrid equation will work (bernouillis for the liquid part, insentropic flow for the gas part), as the gasphase and the liquid phase exchange energy, and there will properbly be some sort entropy change in each phase as a result. Furthermore I do not know the ratio of liquid to gas at the exit of the diffuser. All in all I want to find the stagnation propertis for a wet vapor, knowing its inlet pressure, temperature, quality and velocity.
I have this program called EES (engineering equation solver) which can do the trick, as it can calculate the thermodynamic properties of the fluids. However EES can only solve a static system, and I want to know whether my system is dynamically stable, and I therefore want to use MATLAB to solve the differential equations. However to do this I need a model for the entropy of a wet vapor. When dealing with this by hand you normally resolve to vapor tables, and what EES does it to implement a table-lookup-procedure to find the properties.
When finding the properties of a gas going through a nozzle you normally make an assumption of isentropic flow, and I think a have to do a similar thing. However I cannot figure out how to find the entropy of a wet vapor, without using EES or table lookup. Is there a mathematical way to approximate it?
But I cannot figure out what to do if it is a wet vapor. I do not think using a hybrid equation will work (bernouillis for the liquid part, insentropic flow for the gas part), as the gasphase and the liquid phase exchange energy, and there will properbly be some sort entropy change in each phase as a result. Furthermore I do not know the ratio of liquid to gas at the exit of the diffuser. All in all I want to find the stagnation propertis for a wet vapor, knowing its inlet pressure, temperature, quality and velocity.
I have this program called EES (engineering equation solver) which can do the trick, as it can calculate the thermodynamic properties of the fluids. However EES can only solve a static system, and I want to know whether my system is dynamically stable, and I therefore want to use MATLAB to solve the differential equations. However to do this I need a model for the entropy of a wet vapor. When dealing with this by hand you normally resolve to vapor tables, and what EES does it to implement a table-lookup-procedure to find the properties.
When finding the properties of a gas going through a nozzle you normally make an assumption of isentropic flow, and I think a have to do a similar thing. However I cannot figure out how to find the entropy of a wet vapor, without using EES or table lookup. Is there a mathematical way to approximate it?