| OCR Text |
Show Figure 3. EXPERIMENTAL DOMAIN FOR INVESTIGATION OF COMBUSTION ENHANCEMENT AND FLAME STABILAZATION DUE TO VORTEX GENERATION The holes were evenly distributed across the circle in 90 degree intervals. The hole axes were directed radially. The dimple might be rotated around its axis by any angle so that to bring the holes into various positions with respect to the free stream direction. The natural gas was injected through the holes into the dimple. The ambient air served as the free stream. The air flow velocity upstream the dimple could be varied through the range of U0= 10.5-31.5 m/s, while Reynolds number based upon the dimple diameter /ted=(3.4-10.2)xl04. The turbulence intensity of the free stream was 7wo«2%, and its temperature - r0=300K. The boundary layer thickness in front of the dimple was equal to 5=15 m m . As the upper wall inclination of the working section changed, the shape function |F | (in the case of adverse pressure gradient) was varied through the range of 0-2x IO"3 and the acceleration parameter K (when favourable pressure gradient is imposed) varied from 0 to 5X10"6. During the experiments, the heat flux on the interior surface of the dimple were measured as well as flow and combustion patterns were visualised in the dimple. Local values of heat transfer coefficients were determined by means of gradient method. Q 5 1 4 b Figure 4. A SPHERICAL DIMPLE MODEL: 1 - STREAMLINED SURFACE, 2 SPHERICAL DIMPLE, 3 - HOLES TO SUPPLY ALUMINIUM POWDER, 4- NATURAL GAS FEEDING HOLES, 5 - NATURAL GAS, 6 - ALUMINIUM POWDER 5 |
