BY : CHAM Development Team - M R Malin

FOR : Validation of Gaseous Combustion Models

- The main objective of the calculations is to validate the turbulent
combustion models provided in the extended SCRS attachment for gaseous
combustion.
- The case considered is the turbulent diffusion flame of a round jet of hydrogen in a co-flowing air stream, as studied experimentally by Kent and Bilger (14th Int. Symp. Combustion, p615, 1975).

- The case considered is the turbulent diffusion flame for hydrogen
issuing from a 7.62mm diameter nozzle into a co-flowing stream of air.
- The flame is unconfined and buoyancy and radiation effects are
negligible.
- The ratio of the jet-discharge velocity to the free-stream velocity
is 10. The jet-discharge velocity is 151.1 m/s.
- The free-stream temperature is 288K, which is the same as the jet- discharge temperature.

- Turbulence is represented via the k-e turbulence model, and the turbulent Schmidt number is taken as 0.9.
- Calculations are made with 2 different combustion models: (a) fast-chemistry model with a one-step global irreversible hydrogen reaction to form H2O; (b) as (a) but with an assumed double-delta probability density function to account for the influence of concentration fluctuations;
- The calculations employ variable specific heats and heats of reaction.
- The flow is treated as weakly compressible.
- The calculation is performed using parabolic marching integration with a cylindrical-polar expanding mesh.
- A forward step size of 5% of the local jet radius is employed together with 40 radial grid cells.
- For simplicity, uniform profiles are used at the inlet plane.
- A fixed-pressure condition is used at the free boundary.
1. TURBULENT DIFFUSION FLAME: TEMPERATURE CONTOURS ( DEG K )

2. TURBULENT DIFFUSION FLAME: TEMPERATURE PROFILES AT Z/D=40

3. TURBULENT DIFFUSION FLAME: TEMPERATURE PROFILES AT Z/D=80

4. TURBULENT DIFFUSION FLAME: AXIAL TEMPERATURE DISTRIBUTION

5. TURBULENT DIFFUSION FLAME: MOLE-FRACTION PROFILES AT Z/D=40

6. TURBULENT DIFFUSION FLAME: MOLE-FRACTION PROFILES AT Z/D=80

7. TURBULENT DIFFUSION FLAME: AXIAL COMPOSITION DISTRIBUTION