# Simulating Radial Inflow Turbine - Mass Flow Rate at Inlet not matching outlet

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 March 8, 2019, 10:53 Simulating Radial Inflow Turbine - Mass Flow Rate at Inlet not matching outlet #1 New Member   MoBangi Join Date: Mar 2019 Posts: 5 Rep Power: 6 Hey, i am currently trying to simulate a radial inflow turbine using ansys cfx. I first meshed the rotor and stator in turbogrid. I setup 3 domains in cfx, S1 for the stator, R1 for the rotor and S2 for the outlet. My boundary conditions are total pressure at inlet, total temperature and static pressure at outlet. I have 2 interfaces, stage mixing between S1 and R1. Frozen Rotor between R1 and S2. Simulating real gas (R123) with RGP file. There is currently a difference of around 5% between the mass flow rate at the inlet and mass flow rate at the outlet. (~0.41kg/s inlet, ~0.43/0.44 kg/s outlet)R1.jpg Radial.jpg inlet.jpg outlet.jpg INTERFACE1.jpg

 March 8, 2019, 10:54 #2 New Member   MoBangi Join Date: Mar 2019 Posts: 5 Rep Power: 6 Could not add more than 5 attchments to last post. INTERFACE2.jpg Had to cut out timesteps from 38-300 as the file was too largeOUTFILE.txt Last edited by mobangi12; March 8, 2019 at 12:14. Reason: Added OUT file

 March 8, 2019, 14:06 #3 Senior Member   Join Date: Aug 2012 Posts: 267 Rep Power: 13 Has the simulation fully converged? Have you looked at the imbalances for all domains?

 March 8, 2019, 14:52 #4 New Member   MoBangi Join Date: Mar 2019 Posts: 5 Rep Power: 6 Hey thanks for your reply, the solution was fully converged. I had a few that ran for 1000+ iterations with the same result. I have a theory that its something to do with the fact that i have 22 stator blades and 15 rotor blades. So for each rotor blade there are 22/15 stator blades. Not too sure though. And these ar my imbalances, they dont look too large. +--------------------------------------------------------------------+ | Normalised Imbalance Summary | +--------------------------------------------------------------------+ | Equation | Maximum Flow | Imbalance (%) | +--------------------------------------------------------------------+ | U-Mom-R1 | 9.8032E+01 | -0.0084 | | V-Mom-R1 | 9.8032E+01 | -0.0023 | | W-Mom-R1 | 9.8032E+01 | 0.0000 | | P-Mass-R1 | 2.9154E-02 | 0.0032 | | U-Mom-S2 | 9.8032E+01 | 0.0000 | | V-Mom-S2 | 9.8032E+01 | 0.0000 | | W-Mom-S2 | 9.8032E+01 | 0.0000 | | P-Mass-S2 | 2.9154E-02 | 0.0001 | | U-Mom-S1 | 9.8032E+01 | 0.0009 | | V-Mom-S1 | 9.8032E+01 | -0.0008 | | W-Mom-S1 | 9.8032E+01 | -0.0075 | | P-Mass-S1 | 2.9154E-02 | -0.1077 | +----------------------+-----------------------+---------------------+ | H-Energy-R1 | 1.2675E+04 | 0.0032 | | H-Energy-S2 | 1.2675E+04 | 0.0000 | | H-Energy-S1 | 1.2675E+04 | -0.1099 | +----------------------+-----------------------+---------------------+ ================================================== ==================== Wall Force and Moment Summary ================================================== ====================

 March 8, 2019, 15:06 #5 New Member   MoBangi Join Date: Mar 2019 Posts: 5 Rep Power: 6 Do i maybe need to model 3 nozzles and 2 rotors as opposed to my 1 nozzle and 1 rotor at the moment? Would this affect my solution?

 March 8, 2019, 15:17 #6 Senior Member   Join Date: Aug 2012 Posts: 267 Rep Power: 13 Are you using appropriate expressions to evaluate mass flow at the inlet/outlet? e.g. massFlow()@S1 Inlet*22 massFlow()@S2 Outlet*15

 March 8, 2019, 15:53 #7 New Member   MoBangi Join Date: Mar 2019 Posts: 5 Rep Power: 6 found a way to fix it Last edited by mobangi12; March 8, 2019 at 20:40.

 Tags cfx, interface, mass flow, radial turbine, real gas model

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