Effect of turbine inlet temperature on rotor blade tip leakage flow and heat transfer

Abstract

Purpose

One of the most critical gas turbine engine components, the rotor blade tip and casing, is exposed to high thermal load. It becomes a significant design challenge to protect the turbine materials from this severe situation. The purpose of this paper is to study numerically the effect of turbine inlet temperature on the tip leakage flow structure and heat transfer.

Design/methodology/approach

In this paper, the effect of turbine inlet temperature on the tip leakage flow structure and heat transfer has been studied numerically. Uniform low (LTIT: 444 K) and high (HTIT: 800 K) turbine inlet temperature, as well as non‐uniform inlet temperature have been considered.

Findings

The results showed the higher turbine inlet temperature yields the higher velocity and temperature variations in the leakage flow aerodynamics and heat transfer. For a given turbine geometry and on‐design operating conditions, the turbine power output can be increased by 1.33 times, when the turbine inlet temperature increases 1.80 times. Whereas the averaged heat fluxes on the casing and the blade tip become 2.71 and 2.82 times larger, respectively. Therefore, about 2.8 times larger cooling capacity is required to keep the same turbine material temperature. Furthermore, the maximum heat flux on the blade tip of high turbine inlet temperature case reaches up to 3.348 times larger than that of LTIT case. The effect of the interaction of stator and rotor on heat transfer features is also explored using unsteady simulations. The non‐uniform turbine inlet temperature enhances the heat flux fluctuation on the blade tip and casing.

Originality/value

The increase of turbine inlet temperature is usually proposed to achieve the higher turbine efficiency and the higher turbine power output. However, it has not been reported how much the heat transfer into the blade tip and casing increases with the increased turbine inlet temperature. This paper investigates the heat transfer distributions on the rotor blade tip and casing, associated with the tip leakage flow under high and low turbine inlet temperatures, as well as non‐uniform temperature distribution.

Citation

In Kim, S., Rahman, H. and Hassan, I. (2012), "Effect of turbine inlet temperature on rotor blade tip leakage flow and heat transfer", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 22 No. 1, pp. 73-93. https://doi.org/10.1108/09615531211188801