High thermal load appears at the blade tip and casing of a gas turbine engine. It becomes a significant design challenge to protect the turbine materials from this severe situation. As a result of geometric complexity and experimental limitations, computational fluid dynamics tools have been used to predict blade tip leakage flow aerodynamics and heat transfer at typical engine operating conditions. In this paper, the effect of turbine inlet temperature on the tip leakage flow structure and heat transfer has been studied numerically. Uniform low (444 K) and high (800 K) inlet temperatures and nonuniform (parabolic) temperature profiles have been considered at a fixed rotor rotation speed (9500 rpm). The results showed that the change of flow properties at a higher inlet temperature yields significant variations in the leakage flow aerodynamics and heat transfer relative to the lower inlet temperature condition. Aerodynamic behavior of the tip leakage flow varies significantly with the distortion of turbine inlet temperature. For more realistic inlet condition, the velocity range is insignificant at all time instants. At a high inlet temperature, reverse secondary flow is strongly opposed by the tip leakage flow and the heat transfer fluctuations are reduced greatly.

An unsteady numerical investigation was performed to examine time dependent behaviors of the tip leakage flow structures and heat transfer on the rotor blade tip and casing in a single stage gas turbine engine. A transonic, high-pressure turbine stage was modeled and simulated using a stage pressure ratio of 3.2. The rotor’s tip clearance was 1.2 mm in height (3% of the rotor span) and its speed was set at 9500 rpm. Periodic flow is observed for each vane passing period. Tip leakage flow as well as heat transfer data showed highly time dependent behaviors. A stator trailing edge shock appears as the turbine stage is operating at transonic conditions. The shock alters the flow condition in the rotor section, namely, the tip leakage flow structures and heat transfer rate distributions. The instantaneous Nusselt number distributions are compared to the time averaged and steady-state results. The same patterns in tip leakage flow structures and heat transfer rate distributions were observed in both unsteady and steady simulations. However, the unsteady simulation captured the locally time-dependent high heat transfer phenomena caused by the unsteady interaction with the upstream vane trailing-edge shock and the passing wake.

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Increased temperature of photovoltaic (PV) module decreases its performance; hence, integration of the cooling system is imperative to minimize this detrimental effect. In this study, passive cooling of PV module with different heatsinks have been simulated by thermal models using ANSYS Steady State Thermal software. The results were based on the effect of convective heat transfer coefficients from 5 to 1000 W/m2K for the temperature reduction of PV module using 19 different heatsinks. Three configurations: flat plate heat spreader, fin-only heatsinks, and fin-flat base plate combined heatsinks, have been studied at 35 °C ambient temperature and 800 W/m2 solar radiation. The result shows that at convective heat transfer coefficient of 10 W/m2K, the combined type model C7 and the fin-only type model B4 demonstrated around 18.94 % and 9.36 % lower PV cell temperature, respectively than the flat plat type model A2. Moreover, C7 and B4 models had about 67.5 5% and 78.03 % less material weight than the A2 model, making the heat spreader type least feasible compared to the other two. The temperature contours of the PV cell layer at a given operating condition showed uniform distribution for both flat plate types and combined types. In contrast, the fin-only heatsink configuration illustrated hotspots within the PV cell layer.

In this study, a typical kitchen having a standard dimension of 213cm × 243cm × 305cm was modeled with single open door exit. Steady state simulations were performed using three dimensional commercial CFD solver with appropriate boundary conditions. Two heat sources were used for modelling the kitchen that resembles the double burner gas stoves of urban residential kitchen in developing countries. In the earlier works, for the same model the predictions validated at an optimum grid resolution and the results have been presented for thermal comfort, carbon dioxide gas emission under natural, forced and no ventilation cases. The effect of kitchen hood system on the thermal comfort and emission has also been analyzed. In this present work, three different positions of the kitchen hood suction have been studied for the effect on thermal distribution and emission rate. The investigated positions of the kitchen hood are the Front, Top and Bottom with respect to the gas stove. It was observed that both front and bottom hood extraction method significantly reduces the emissions to well below the safe limit. They also can maintain thermal comfort quite well inside the kitchen space.