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A casted leaded-bronze block was impinged by a circular water jet. A 30-fps digital camera was used to video record the wet front propagation process on the surface of the block. The video frames were analyzed to illustrate the effect of different key parameters on the wetting front propagation. Regression correlations were developed to describe the effect of the jet Reynolds number (Red), the ratio of the degree of jet subcooling to the initial temperature of the block ΔTsubTi and the nozzle-to-surface spacing (H) on the wetting front propagation. The correlation is applicable for the experimental ranges investigated; 12,155 ≤ Red ≤ 36,460, 0.085 ≤ TsubTi ≤ 0.107 and H ≥ 30 mm. Good agreement was found between the experimental results and the correlation predictions with a maximum deviation of 25%. At high Reynolds number, the wetting front propagation was faster due to the high velocity and flow inertia. As the ratio ΔTsubTi increased, the wetting front propagation was accelerated. The effect of the nozzle-to-surface height on the propagation speed was negligible for H ≥ 30 mm. The effect of the increased liquid head on the terminal velocity was weakened by the drag forces on the jet as well as the jet instabilities associated with the large spacing. Keywords: Jet impingement, Quenching, Wetting front propagation

This paper shows a numerical investigation on smoke management techniques inside a large building. Fifteen numerical simulations were carried out using fire dynamic simulator FDS software. The effect of adding a mechanical exhaust louver on the roof inside the building is studied. This was carried out by varying the exhaust ACH and the configuration of the exhaust openings. Also, the effect of injecting fresh air into the building was examined by investigating the effect of changing the make-up air ACH and the location of the make-up air. All cases were analyzed by studying the smoke layer height, mean soot density and the mean temperature of smoke.It was observed that the smoke hazard decreases by increasing ACH, using multiple exhaust points, and adding make-up air. As compared to no smoke management, this enhancement reaches 71.18% for the smoke layer, 31.6% lowering the average temperature, and 38.4% decreasing the average soot density. These results were achieved when six opposed supply louvers and one exhaust louver were used for the smoke management system. Keywords: Smoke management, Atrium, Mall, Large buildings, Smoke layer height, Fire dynamic simulator

Experiments were conducted on a flat plate to investigate the influence of the wire mesh on the jet impingement cooling rates. Three different mesh sizes were used to be compared to a bare surface. Inverse heat conduction technique was used to estimate the surface heat flux and temperature without interfering with the flow/boiling phenomena occurring on the surface. The heat flux ratio between the meshed and the bare surface was found to be always less than unity; from 0.6 up to 1.0, which indicated heat transfer deterioration. The bare surface was found to have the lowest temperature gradients due to the fast wetting and uniform heat transfer induced by the impingement process; the increase was found to be 5–25% when compared to bare surface. For the meshed surface, higher temperature gradients were observed due to the localized boiling phenomenon, resulting in non-uniform heat transfer on the surface. Three mesh numbers were Mdw = 0.22, 0.28 and 0.34. At Mdw = 0.28, better cooling rates (closer to the case with bare surface) than the other two cases. An optimum Mdw at which the augmentation of heat transfer due to the wire mesh is not offsetted by the wetting resistance effects was noticed. Keywords: Wire mesh, Flat plate, Jet impingement, Quenching