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MECH 523 Applied CFD Sagar Kapadia

Numerical study of the blade cooling effect generated by multiple jets issuing at different angles and speed into a compressible horizontal cross flow. MECH 523 Applied CFD Sagar Kapadia. Content. Industrial Applications Geometry, Grid and Design Parameters

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MECH 523 Applied CFD Sagar Kapadia

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  1. Numerical study of the blade cooling effect generated by multiple jets issuing at different angles and speed into a compressible horizontal cross flow. MECH 523 Applied CFD Sagar Kapadia

  2. Content • Industrial Applications • Geometry, Grid and Design Parameters • Governing Equations (N-S) And Solver – Cobalt • Finite Volume Method • Turbulence Model (DES) • Results And Discussion • Conclusion and Future Scope

  3. Industrial Applications Take off and landing engineering Film cooling of Turbine blades Jets into combustors

  4. Geometry 0.2m 0.2m Cool Jet 0.9m Hot Crossflow

  5. Design Variables

  6. Grid Information Grid has been created using Gridgen- 14.03 preprocessor. Grid information: Unstructured Grid Number of nodes = 121316 Number of elements = 651499 Element Type – Tetrahedran Quality of the grid = 99.78 % (Blacksmith)

  7. Solver:Cobalt A parallel, implicit, unstructured Euler/Navier-Stokes Flow solver. It was developed in the computational science branch of the Air-Force. This code is used to solve the high speed, highly separated flow problems. Six different turbulence models are available in this code for different kind of simulation. (1) S-A model. (2) DES/S-A model. (3) Menter Baseline (BSL). (4) Menter Baseline + Shear Stress Transport (SST). (5) DES/M-SST. (6) Wilcox k-. Spatial Accuracy : Second Order. Temporal Accuracy : Second Order. CFL can be as large as 1000000.

  8. Governing Equation

  9. x w i,j+1/2 . i,j i+1/2,j y z i,j-1/2 Finite Volume Method . . . . . . . . . . . . i-1/2,j y . . . . x

  10. x w i,j+1/2 . i,j i+1/2,j i-1/2,j y z i,j-1/2 Discretization

  11. Discretization

  12. x x1 w1 w Mirror Cell . . i,j+1/2 2 1 y y1 z z1 Implementation of Boundary Condition in Finite Volume Boundary • P1=P2, • u1 = -u2 • (No-Slip Condition) • v1 = -v2 • T1=T2 • (Adiabatic)

  13. Model Boundary Conditions Boundary Condition Type Inputs Inlet Source P, T= 3000K, Mach Number=0.3, Turbulence Viscosity Hole User-Defined Density,Velocity profile (depends on R), P, Turbulence Viscosity Blade Adiabatic Wall No-Slip Condition Open Faces Farfield P, T, Mach Number, Turbulent Viscosity(Ref. Condition) Symmetry Symmetry Symmetric Wall (Gradient of all physical quantity is zero). Outlet Pressure Outlet Static Pressure = 101325 Pa

  14. Turbulence Model :Detached Eddy Simulation (DES) Purpose of DES – To overcome the disadvantages of LES and RANS Hybrid Turbulence Model of, (1) RANS and (2) LES Used for High Speed, Massively separated flows . RANS - Attached Boundary Layers LES - Separated Regions. Presently available definition of DES is not related with any particular turbulence model. DEFINITION : DES is a 3-D unsteady numerical solution using single turbulence model which functions as a sub-grid scale model in the regions where grid density is fine enough for LES and as a RANS where it is not. “fine enough” – when maximum spatial step,is much smaller than the flow turbulence length scale,

  15. Overview of Spalart-Allmaras(S-A) Based DES Model

  16. Flow Visualization-Temperature Distribution (400 time steps)

  17. Flow Visualization- Vortex Formation

  18. Temperature Contours for R =1 and  = 35o x = 0.297561

  19. Temperature Contours for R =2.50 and  = 20o x= 0.465534

  20. Temperature Contours for R = 2 and  = 20o x = 0.5121495

  21. Cooling Effect Obtained by the recirculation of the cold air

  22. Conclusion • Three different combinations of R (blowing ratio) and  (angle of attack) has been used to measure the cooling effect after 400 time steps. • Maximum cooling is obtained with R = 2 and  = 20o combination. • Minimum cooling is obtained with R = 1 and  = 35o combination. • Solution is unsteady after 400 time steps. • Cooling effect is the combined function of blowing ratio and .

  23. Future Scope • To solve the problem with more combinations of R and . • To get the steady state solution for the cases described in the presentation and compare the cooling. • To find out the optimum combination of Blowing Ratio and Angle of attack of the jet for maximum cooling.

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