Summary
This study presents the numerical calculations of the fluid flow and turbulent heat transfer characteristics of hot flow over a sudden-expansion with cold air base mass injection. The turbulent governing equations are solved by a control-volume-based finite-difference method with power-law scheme, the well knownk-ε model, and its associate wall function to describe the turbulent behavior. The velocity and pressure terms of momentum equations are solved by the SIMPLE (Semi-Implicid Method for Pressure-Linked Equation) method. In this study non uniform staggered grids are used. The parameters interested include the inlet Reynolds number (Re), inlet temperature (T0), and the injection flow rate (Q). The numerical results show that the reattachment lengths are reasonably predicted with a maximum discrepancy within 9.1%. It also shows that the base mass injection suppresses the horizontal velocity and turbulence intensity. In these high temperature heat transfer characteristics, the heat transfer coefficient increased with increasing inlet temperature and inlet Reynolds number, but decreased with increasing injection flow rate of the cooling air.
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Abbreviations
- C 1,C 2,C μ :
-
turbulent constant
- E :
-
constant
- G :
-
generation rate of turbulent kinetic energy
- H :
-
channel height at inlet
- i :
-
turbulence intensity
- k :
-
turbulent kinetic energy
- Nu:
-
local Nusselt number
- q ″w :
-
heat flux
- Re:
-
Reynolds number
- S ϕ :
-
source term
- T :
-
temperature
- T 0 :
-
inlet temperature
- TI :
-
turbulent intensity
- U 0 :
-
inlet velocity
- U τ :
-
friction velocity
- U,V :
-
x, y component velocity
- \(\overline {u\upsilon } \) :
-
Reynolds shear stress
- X τ :
-
reattachment length
- y + :
-
dimensionless distance from the wall
- ϕ:
-
dependent variables
- Ή φ :
-
diffusion coefficient ofφ equation
- α:
-
thermal diffusivity of fluid
- ρ:
-
density
- κ:
-
von Kármán constant
- σ:
-
turbulent Prandtl number
- μ:
-
dynamic viscosity
- ν:
-
kinematic viscosity
- τ w :
-
wall shear stress
- ε:
-
turbulent energy dissaption rate
- λ:
-
length scale constant
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Yang, Y.J., Yan, Z.S. & Chen, C.K. Numerical study of turbulent heat transfer and flow characteristics of hot flow over a sudden-expansion with base mass injection. Acta Mechanica 144, 57–69 (2000). https://doi.org/10.1007/BF01181828
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DOI: https://doi.org/10.1007/BF01181828