Amongst all the multiphase models in the lattice Boltzmann (LB) community, the pseudopotential model has been the most popular approach due to its simplicity and high-efficiency. Recently a number of liquid-vapour phase change models were also proposed based on the pseudopotential LB model. Our study finds that most of the published pseudopotential phase change models rely on an entropy-based energy equation, while the entropy-based energy equation is derived with the equation of state of ideal gas. That means this entropy-based energy equation is not completely suitable for multiphase flow which applies non-ideal equation of state for the phase separation simulation. Therefore a new phase change LB model is proposed in this work, where an improved pseudopotential multiphase model (Li et al., 2013) and a modified energy equation which is solved in the classical fourth-order Runge-Kutta scheme are coupled in a hybrid scheme. The results show that the numerical simulation can capture the basic liquid-vapour phase change features. The D 2 law for droplet evaporation is validated and the square of diameter variation is in good agreement with experimental data. Moreover, the three boiling stages (nucleate boiling, transition boiling and film boiling) are accomplished using the modified model, and the corresponding transient heat fluxes are presented.
In this paper, experimental and numerical study has been carried out to investigate impingement cooling with a row of five circular jets, varied between target positions on a realistic leading edge region of a gas turbine blade geometry. Experimental data is collected from a transient thermochromic liquid crystal measurement technique at the target surface.Numerical study was conducted with the geometry using commercial computational fluid dynamics software to analyse the fluid flow. The unique aims of the study are to observe the effects of variation in jet location, and those specific to realistic target and nozzle geometries.Distributions of local and average Nusselt number show that a location targeting the concave surface at 90° demonstrates an overall higher heat transfer coefficient, especially in the stagnation region, and towards the aerofoil sides, with significantly less swirl. The experiment was performed with the following parameters: distance from nozzle to target of 1.7 to 2.1 jet diameters, pitch between jets of 4.4 jet diameters, and concave target diameter of 8.0 jet diameters. The jet Reynolds number range during this test was 20,000 -40,000. A standard flat target plate impingement test is also experimentally conducted and compared against existing literature for method validation.
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