Abstract
The gas turbine is a kind of high-power and high-performance energy machine. Currently, it is a hot issue to improve the efficiency of the gas turbines by reducing the amount of secondary air used in the disk cavity. The precondition is to understand the effects of the through-flow rate on the axial thrust, the disk frictional losses, and the characteristics of heat transfer under various experimental conditions. In this paper, experiments are conducted to analyze the characteristics of flow and heat transfer. To ensure the safe operation of the gas turbine, the pressure distribution and the axial thrust are measured for various experimental conditions. The axial thrust coefficient is found to decrease as the rotational speed and the through-flow rate increases. By torque measurements, the amounts of the moment coefficient drop as the rotational speed increases while increase with through-flow rate. In order to better analyze the temperature field within the cavity, both the local and the average Nusselt number are investigated with the help of thermochromic liquid crystal technique. Four correlations for the local Nusselt number are determined according to the amounts of a through-flow coefficient. The results in this study can help the designers to better design the secondary air system in a gas turbine.
Highlights
Gas turbines are widely used in the fields of aircraft propulsion and power generation
According to the experience of the authors’ group, the amount of secondary air used in the disk cavity comprises around 6% of the mass flow at the compressor inlet [1]
Metzger et al [15] measured the radial distributions of the local heat transfer coefficient h, defined in Equation (9)
Summary
Gas turbines are widely used in the fields of aircraft propulsion and power generation. The parameter K, defined in Equation ∂r (3), is the ratio of the angular velocity of the fluid at half of the K axial gap core widthswirl ζ = 0.5 to that of the disk. Metzger et al [15] measured the radial distributions of the local heat transfer coefficient h, defined in Equation (9). According to their results, the heat transfer can be enhanced when the parameters, such as Re, Cw , and G, are synthetically optimized. The obtained results can help the designers to reduce the amount of air used in the disk cavity reasonably
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