Ideas about Gas - Solid Cyclone Separator Simulations
Hi;
Im trying to simulate gas-solid cyclone separator used in cement industry. I will mention about boundary conditions and operating conditions. I need some ideas to solve more accurate , quicker solution with same accuracy or to correct my mistakes. These will helpful for me and for others who has need help on this subject. operating conditions ; - It is a multilevel system consists of 5 cyclone levels. - very high dust loading particle.( 0.2 kg particle/ m^3 air) - 12 to 20 m/s inlet velocity - nearly 700 m^3 control volume Boundary Conditions; 1 - velocity inlet 2 - pressure outlet or outflow ****normally outlet is not open to atmosphere. Gas always goes to upper cyclone level. So there must not be reverse flow. 3 - wall ,of cyclone body 4 - wall of dust outlet Setup settings; 1 - Mesh count : 160K , 700K , 3M, 8M , 30M 2 - Eularian multiphase model with dense DPM option. 3 - Reynols stress model with linear pressure strain option 4 - pressure-velocity coupling scheme; ----Simple : there is no need to set a CFL but long computational time. ----Coupled : I have enough memory. But in Fluent theory manual, it says below 10 is not recommended for Courant number. And if you can't choose wright CFL in coupled , solution monitors fluctuates a lot. 5 - Spatial Discretization ; ---- Gradient :Green Gauss node based ---- Pressure : Presto ---- others : second or third order upwind---- solution monitors fluctuates a lot. So it says you to switch time-dependent simulation. 6 - Under Relaxation Factors : 0.5 for all parameters 7 - Initialization : Normal + FMG with 7 levels QUESTIONS 1 - I will use Multi-Objective algorithm to get functions of separation efficiency and pressure loss depending on geometric and flow parameters. I could not get efficiency directly . I use 17 injections for 17 different diameters, I need efficiency for all diameters like output parameters. 2 - Is it necessary to set a boundary layer mesh while using RSM ? 3 - Which model would be more suitable for particle drag force calculations ? Thank you in advance |
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