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How to spray gas-fuel in converge

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Old   February 24, 2017, 04:03
Default How to spray gas-fuel in converge
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liyong
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Hello engineers,
Iím a student, studying in Tianjin University. I want to simulate the combustion of hydrogen-direct inject engine. However, I canít use spray modeling, because parcel simulation must be select when spray modeling is selected, and in parcel simulation a liquid and its characters are needed to add. As we all know, hydrogen is gas, so there is no atomization in process of injection.
So may you help me how to inject the hydrogen into chamber? And how to setup the mass of injected hydrogen and pressure of injection? And do you have the example about gas-fuel direct injection simulation?
Thank you!
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Old   February 26, 2017, 20:43
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Quote:
Originally Posted by luckyboy View Post
Hello engineers,
Iím a student, studying in Tianjin University. I want to simulate the combustion of hydrogen-direct inject engine. However, I canít use spray modeling, because parcel simulation must be select when spray modeling is selected, and in parcel simulation a liquid and its characters are needed to add. As we all know, hydrogen is gas, so there is no atomization in process of injection.
So may you help me how to inject the hydrogen into chamber? And how to setup the mass of injected hydrogen and pressure of injection? And do you have the example about gas-fuel direct injection simulation?
Thank you!
Read this paper.
"A Computational Study of the Mixture Preparation in a DirectĖInjection Hydrogen Engine"
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Old   February 27, 2017, 08:04
Default How to spray gas-fuel in converge
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Originally Posted by whysoserious View Post
Read this paper.
"A Computational Study of the Mixture Preparation in a DirectĖInjection Hydrogen Engine"
Hello,
I have read the paper, and I have met some troubles. Can you help me?
First, in that paper, mass flow rate is used as the boundary condition for the fuel injection, but in CONVERGE, if mass flow has been selected in velocity boundary condition the box of total pressure canít be selected in pressure boundary condition. So how to set the injection pressure?
Second, in CONVERGE, is it necessary to use Events between region cylinder and region injector for injection duration? (or is it necessary to build a region for injector?) If yes, in Regions and initialization for injector region, the temperature and the pressure is for fuel? And how to set Turbulence initialization? If no, where does the injection duration set?
Iím a new learner for converge, so there are many troubles for me. I am sorry to excuse you and please help me. Thank you!
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Old   February 27, 2017, 16:40
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Dan Probst
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Injecting a gaseous fuel such as hydrogen should be done with an inflow boundary.
You cannot set both the massflow and pressure boundary conditions without over specifying the problem. I would suggest trying the problem with either a massflow or pressure boundary condition, depending on what data you have available to specify the problem.
Unless you are including detail of the hydrogen injector, you do not to create a region for the injector.
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Old   February 27, 2017, 21:14
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But how can I set injection duration if I just set pressure boundry condition? what is the pressure of inflow condition after injection, which mean injection stop?
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Old   February 28, 2017, 03:09
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If you specify a INFLOW boundary and support a massflow.in file, you can easily define the injection duration. Thats the way i went with my master thesis (numerical simulation of CNG-H2 fueled CAI engine).
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Old   March 1, 2017, 07:55
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Hello,
When I simulate the hydrogen directly injection, the solver report the error:
” ncyc= 39, time= -1.522219713e-002, crank= -1.369997742e+002, dt= 1.000000000e-008, time-step limit =dt_min forced by dt_cfl
it = 1, WARNING ... extrapolating on the temperature calculation
it = 1, WARNING ... extrapolating on the temperature calculation
it = 1, WARNING ... extrapolating on the temperature calculation
it = 1, WARNING ... extrapolating on the temperature calculation
Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is -1.#IND00, and lower_energy_value is -1.#IND00 .
Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is -1.#IND00, and lower_energy_value is -1.#IND00.”
Can you tell me what cause the error?
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Old   March 1, 2017, 08:47
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Quote:
Originally Posted by luckyboy View Post
Hello,
When I simulate the hydrogen directly injection, the solver report the error:
Ē ncyc= 39, time= -1.522219713e-002, crank= -1.369997742e+002, dt= 1.000000000e-008, time-step limit =dt_min forced by dt_cfl
it = 1, WARNING ... extrapolating on the temperature calculation
it = 1, WARNING ... extrapolating on the temperature calculation
it = 1, WARNING ... extrapolating on the temperature calculation
it = 1, WARNING ... extrapolating on the temperature calculation
Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is -1.#IND00, and lower_energy_value is -1.#IND00 .
Something is wrong in function get_temp_from_table_massfrac: upper_energy_value must be greater than lower_energy_value!
upper_energy_value is -1.#IND00, and lower_energy_value is -1.#IND00.Ē
Can you tell me what cause the error?
Someone else has asked this question. you can find the explanation through search application.
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