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Centrifugal fan-reverse flow in outlet lesds to a mass in flow field |
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March 29, 2017, 05:30 |
Centrifugal fan-reverse flow in outlet lesds to a mass in flow field
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#1 |
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Hi, i am try to simulate a centrifugal fan, and try to estimate the effiency (just only impeller, so i add a former extention and a latter one, just can see in the images).
inlet is massflow(rated flow),outlet is static pressure, the number of fans is 17. question is :along the solving process,in the early iterations,the result seems just OK,and the RMS decrease. but with the iteratons increase,the solver manager show that a reverse flow in the outlet,and always exsisting,and the RMS tendency becomes unstable,the flow field of result is unsymmetric. i have tried to change the outlet to opening, and change to a high quality mesh and so on,but the problem always existing. i really want to know is this phenomenon is just normal exsisting or just the numerical problem(somewhere i am wrong). thanks a lot! |
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March 29, 2017, 05:33 |
here my CEL
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#2 |
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LIBRARY:
CEL: EXPRESSIONS: NJ = torque_z()@R2 Blade+torque_z()@R2 Hub+torque_z()@R2 Shroud desty = 4.003[g/mol]*Absolute Pressure /(R*Temperature ) dp = massFlowAve(Total Pressure in Stn Frame )@S2 \ Outlet-massFlowAve(Total Pressure in Stn Frame )@s1inlet END END MATERIAL: he Material Group = User Option = Pure Substance Thermodynamic State = Gas PROPERTIES: Option = General Material EQUATION OF STATE: Molar Mass = 4.003 [kg kmol^-1] Option = Ideal Gas END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 5189.4 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END REFERENCE STATE: Option = Specified Point Reference Pressure = 7 [MPa] Reference Specific Enthalpy = 2744337.8 [J kg^-1] Reference Specific Entropy = 22105.7 [J kg^-1 K^-1] Reference Temperature = 250 [C] END DYNAMIC VISCOSITY: Dynamic Viscosity = 0.00003 [Pa s] Option = Value END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 0.2333 [W m^-1 K^-1] END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K] Time Units = [s] END ANALYSIS TYPE: Option = Steady State EXTERNAL SOLVER COUPLING: Option = None END END DOMAIN: R2 Coord Frame = Coord 0 Domain Type = Fluid Location = Entire Passage BOUNDARY: R2 Blade Boundary Type = WALL Frame Type = Rotating Location = Entire BLADE BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Adiabatic END MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: R2 Hub Boundary Type = WALL Frame Type = Rotating Location = Entire HUB BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Adiabatic END MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: R2 Shroud Boundary Type = WALL Frame Type = Rotating Location = Entire SHROUD BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Adiabatic END MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: r2 to s2 Side 1 Boundary Type = INTERFACE Location = Entire OUTFLOW BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Conservative Interface Flux END MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: s1 to r2 Side 1 1 Boundary Type = INTERFACE Location = Entire INFLOW BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Conservative Interface Flux END MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Alternate Rotation Model = true Angular Velocity = 4000 [rev min^-1] Option = Rotating AXIS DEFINITION: Option = Coordinate Axis Rotation Axis = Coord 0.3 END END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: He Ideal Gas Material = he Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Include Viscous Work Term = True Option = Total Energy END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = k epsilon END TURBULENT WALL FUNCTIONS: High Speed Model = Off Option = Scalable END END END DOMAIN: S2 Coord Frame = Coord 0 Domain Type = Fluid Location = HFLUID BOUNDARY: S2 Outlet Boundary Type = OPENING Location = HOUTLET BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END HEAT TRANSFER: Option = Static Temperature Static Temperature = 530 [K] END MASS AND MOMENTUM: Option = Entrainment Relative Pressure = 7.2 [MPa] PRESSURE OPTION: Option = Static Pressure END END TURBULENCE: Option = Zero Gradient END END END BOUNDARY: r2 to s2 Side 2 Boundary Type = INTERFACE Location = HINLET BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Conservative Interface Flux END MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: s2updown Boundary Type = WALL Location = HDOWNFACE,HUPFACE BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Adiabatic END MASS AND MOMENTUM: Option = Free Slip Wall END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: He Ideal Gas Material = he Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Include Viscous Work Term = True Option = Total Energy END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = k epsilon END TURBULENT WALL FUNCTIONS: High Speed Model = Off Option = Scalable END END END DOMAIN: s1 Coord Frame = Coord 0 Domain Type = Fluid Location = FFLUID BOUNDARY: s1 to r2 Side 2 1 Boundary Type = INTERFACE Location = FOUTLET BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Conservative Interface Flux END MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: s1cemian Boundary Type = WALL Location = FCEMAIN BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Adiabatic END MASS AND MOMENTUM: Option = Free Slip Wall END END END BOUNDARY: s1inlet Boundary Type = INLET Location = FINLET BOUNDARY CONDITIONS: FLOW DIRECTION: Option = Normal to Boundary Condition END FLOW REGIME: Option = Subsonic END HEAT TRANSFER: Option = Static Temperature Static Temperature = 250 [C] END MASS AND MOMENTUM: Mass Flow Rate = 96 [kg s^-1] Mass Flow Rate Area = As Specified Option = Mass Flow Rate END TURBULENCE: Option = Zero Gradient END END END BOUNDARY: s1solid Boundary Type = WALL Location = FSOLID BOUNDARY CONDITIONS: HEAT TRANSFER: Option = Adiabatic END MASS AND MOMENTUM: Option = No Slip Wall WALL VELOCITY: Angular Velocity = 4000 [rev min^-1] Option = Rotating Wall AXIS DEFINITION: Option = Coordinate Axis Rotation Axis = Coord 0.3 END END END WALL ROUGHNESS: Option = Smooth Wall END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: He Ideal Gas Material = he Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Include Viscous Work Term = True Option = Total Energy END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = k epsilon END TURBULENT WALL FUNCTIONS: High Speed Model = Off Option = Scalable END END END DOMAIN INTERFACE: r2 to s2 Boundary List1 = r2 to s2 Side 1 Boundary List2 = r2 to s2 Side 2 Interface Type = Fluid Fluid INTERFACE MODELS: Option = General Connection FRAME CHANGE: Option = Frozen Rotor END MASS AND MOMENTUM: Option = Conservative Interface Flux MOMENTUM INTERFACE MODEL: Option = None END END PITCH CHANGE: Option = Specified Pitch Angles Pitch Angle Side1 = 360 [degree] Pitch Angle Side2 = 360 [degree] END END MESH CONNECTION: Option = GGI END END DOMAIN INTERFACE: s1 to r2 Boundary List1 = s1 to r2 Side 1 1 Boundary List2 = s1 to r2 Side 2 1 Interface Type = Fluid Fluid INTERFACE MODELS: Option = General Connection FRAME CHANGE: Option = Frozen Rotor END MASS AND MOMENTUM: Option = Conservative Interface Flux MOMENTUM INTERFACE MODEL: Option = None END END PITCH CHANGE: Option = Specified Pitch Angles Pitch Angle Side1 = 360 [degree] Pitch Angle Side2 = 360 [degree] END END MESH CONNECTION: Option = GGI END END OUTPUT CONTROL: BACKUP RESULTS: Backup Results 1 Extra Output Variables List = Absolute Pressure File Compression Level = Default Option = Standard Output Equation Residuals = All OUTPUT FREQUENCY: Iteration Interval = 100 Option = Iteration Interval END END MONITOR OBJECTS: MONITOR BALANCES: Option = Full END MONITOR FORCES: Option = Full END MONITOR PARTICLES: Option = Full END MONITOR POINT: niuju Coord Frame = Coord 0 Expression Value = NJ Option = Expression END MONITOR POINT: ych Coord Frame = Coord 0 Expression Value = dp Option = Expression END MONITOR RESIDUALS: Option = Full END MONITOR TOTALS: Option = Full END END RESULTS: File Compression Level = Default Option = Standard END END SOLVER CONTROL: Turbulence Numerics = High Resolution ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Length Scale Option = Conservative Maximum Number of Iterations = 1000000 Minimum Number of Iterations = 1 Timescale Control = Auto Timescale Timescale Factor = 1 END CONVERGENCE CRITERIA: Residual Target = 0.00001 Residual Type = RMS END DYNAMIC MODEL CONTROL: Global Dynamic Model Control = On END END END COMMAND FILE: Version = 16.0 Results Version = 16.0 END SIMULATION CONTROL: EXECUTION CONTROL: EXECUTABLE SELECTION: Double Precision = Yes END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.2 END END PARALLEL HOST LIBRARY: HOST DEFINITION: dellpc Remote Host Name = DELL-PC Installation Root = D:\ANSYS16.0\ANSYS Inc\v%v\CFX Host Architecture String = winnt-amd64 END END PARTITIONER STEP CONTROL: Multidomain Option = Automatic Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.2 END PARTITION SMOOTHING: Maximum Partition Smoothing Sweeps = 100 Option = Smooth END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic Partition Weight Factors = 0.10000, 0.10000, 0.10000, 0.10000, \ 0.10000, 0.10000, 0.10000, 0.10000, 0.10000, 0.10000 END END RUN DEFINITION: Solver Input File = E:\2017-3-27\wu-yplu-try\66\66_002.res Run Mode = Full Solver Results File = E:\2017-3-27\wu-yplu-try\66\66_003.res END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.2 END PARALLEL ENVIRONMENT: Number of Processes = 10 Start Method = Platform MPI Local Parallel Parallel Host List = dellpc*10 END END END END |
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March 29, 2017, 09:49 |
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#3 |
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Instead of using those BC, I would use total pressure at the inlet and mass flow rate at the outlet. It is usually recommended when you have rotating domains.
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March 29, 2017, 10:00 |
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#4 |
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very appreciate for your advice,but i don't know the total pressure in the inlet.(but i've tried static pressure as inlet,and massflow as outlet,also remains the problem), i attached the RMS for you(i thank the later iterations is somewhere wrong)
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centrifugal fan impeller, reverse flow, unsymmetric flow field |
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