Computational Analysis of Droplet Mass and Size Effect on Mist/Air Impingement Cooling Performance

Abstract

Impingement cooling has been widely employed to cool gas turbine hot components such as combustor liners, combustor transition pieces, turbine vanes, and blades. A promising technology is proposed to enhance impingement cooling with water droplets injection. However, previous studies were conducted on blade shower head film cooling, and less attention was given to the transition piece cooling. As a continuous effort to develop a realistic mist impingement cooling scheme, this paper focuses on simulating mist impingement cooling under typical gas turbine operating conditions of high temperature and pressure in a double chamber model. Furthermore, the paper presents the effect of cooling effectiveness by changing the mass and size of the droplets. Based on the heat-mass transfer analogy, the results of these experiments prove that the mass of 3 − 3 kg/s droplets with diameters of 5-35 m could enhance 90% cooling effectiveness and reduce 122 K of wall temperature. The results of this paper can provide guidance for corresponding experiments and serve as the qualification reference for future more complicated studies with convex surface cooling.

Study of Impingement Cooling Technology by Using Circular Pin Fins and Mist/Air Methods in Gas Turbine Combustor

“…Comparison of the temperature and cooling effectiveness results is shown in Figure 3. From the reference [3,22], 5 μm is the optimized size of droplets which could provide a better heat transfer performance. The inner wall was each mode of three equally spaced regions.…”

Numerical Simulation on the Effect of Turbulence Models on Impingement Cooling of Double Chamber Model

“…In this model, the equation is the same as in RNG model; however is not a constant and varies as a function of mean velocity field and turbulence (0.09 in log-layer ( / ) = 3.3, 0.05 in shear layer of ( / ) = 6). The equation is based on a transport equation for the meansquare vorticity fluctuation [14] as…”

Heat Transfer Designed for Bionic Surfaces with Rib Turbulators Inspired by Alopias Branchial Arch in a Simplified Gas Turbine Transition Piece

“…The CFD simulation models were employed and the results indicated that heat transfer effectiveness was improved with the rising hole's inclination and injection angle, since the thermal surface was impinged by more coolant directly. They [7], also investigated that jet flow with water drop promoted impinging cooling efficiency increasing. They concluded the mass of 3 × 10 −3 kg/s droplets with diameters of 5-35 µm could enhance the 90% cooling effectiveness and reduce 122 K of surface temperature.…”