Aerothermal Performance of Turbine Blade Tips

In modern gas turbines, the interface between the rotating blade tips and the surrounding casing represents a critical zone for both aerodynamic efficiency and thermal management. The small clearance at the blade tip allows high-pressure gas to leak from the pressure side to the suction side, forming complex vortical structures that give rise to increased aerodynamic losses and localised heat loads. These aerothermal interactions are further complicated by shock waves in transonic regimes, the thermal coupling between the hot gas and blade wall, and the need to maintain structural integrity at elevated temperatures. Various tip geometries, notably the cavity-based “squealer” design, have been deployed to manipulate leakage vortices and reduce heat transfer coefficients. Complementary cooling techniques—such as discrete film holes or full conjugate heat transfer approaches—seek to establish a protective coolant film over the tip surface. Advances in computational methods, including unsteady Reynolds-Averaged Navier–Stokes (URANS), Detached Eddy Simulation (DES) and high-fidelity conjugate heat transfer (CHT) simulations, alongside novel experimental techniques like focusing schlieren imaging, have elucidated the interplay of flow structures, vortex dynamics and temperature fields. Optimising blade tip aerothermal performance offers significant benefits in stage efficiency, fuel consumption and component life, with implications across aero-engines, power generation and industrial turbines.

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Aerothermal Performance of Turbine Blade Tips publication trend

The graph below shows the total number of articles in aerothermal performance of turbine blade tips across all publications each year (not limited to Nature Index journals).

Technical terms

Tip clearance: gap between the rotating blade tip and the engine casing that governs leakage flow and aerodynamic loss.

Tip leakage vortex (TLV): swirling flow structure formed as high-pressure gas leaks through the tip clearance, contributing to aerodynamic and thermal losses.

Squealer tip: a recessed rim around the blade tip designed to modify leakage flow and reduce heat transfer rates.

Film cooling: a technique in which coolant is ejected through discrete holes on the blade tip or surface to create a protective thermal barrier.

References

1. Focusing Schlieren Visualization of Transonic Turbine Tip-Leakage Flows †. International Journal of Turbomachinery Propulsion and Power (2020).
2. Turbine Blade Tip External Cooling Technologies. Aerospace (2018).
3. Influence of Shock Wave on Loss and Breakdown of Tip-Leakage Vortex in Turbine Rotor with Varying Backpressure. Applied Sciences (2021).
4. Influence of Gas-to-Wall Temperature Ratio on the Leakage Flow and Cooling Performance of a Turbine Squealer Tip. Aerospace (2022).
5. Numerical Study on Vortex Structures and Loss Characteristics in a Transonic Turbine with Various Squealer Tips. Energies (2022).
6. Numerical investigations on the unsteady leakage flow and heat transfer characteristics of the turbine blade squealer tip. Journal of the Global Power and Propulsion Society (2023).