The engine-cycle performance of a jet engine can be improved by more efficient cooling systems, either by using less cooling air or by achieving more intensive cooling with the same amount of cooling mass flow. However, the multitude of geometrical parameters and the strong multidisciplinary aspect of the cooling mass flow consumption optimization make designing the cooling systems an extremely challenging task. The integration of probabilistic methods into the thermal design process of cooling systems enables the automated evaluation of multiple design variants and can thus contribute to the development of more efficient systems.In the present study, the sensitivity of a multi-pass cooling system with rib-roughened walls to geometric variations is investigated. The aim is to identify the most influential design parameters and analyze their complex interactions with the system behavior.The performance of the cooling system is evaluated based on the cooling mass flow consumption, the maximum material temperature and the total pressure change throughout the system. To calculate these quantities, the cooling air flow, simulated using a one-dimensional, correlation based flow solver, is iteratively coupled with the three-dimensional thermal analysis of the blade.To apply geometrically meaningful variations to the cubic spline based three-dimensional model of the cooling system, the Harmonic-Spline-Deformation method is used. This method, so far limited to the variation of parameter distributions along the blade radius, has been extended by 7 additional variables to modify a characteristic parameter distribution along the profile circumference. With this extension it is possible to vary the wall thickness of the blade, which significantly influences the blade temperature as a result of the conduction through the blade material.Furthermore two probabilistic methods, the Elementary-Effects-Method and the Monte-Carlo based sensitivity analysis, are compared. For the evaluation of the Monte-Carlo simulation different stochastic methods are investigated to quantify the effect of the design parameters onto the system behavior.It is shown that the Elementary-Effects-Method and the Monte-Carlo based sensitivity analysis show a good agreement in the identification of the influencing parameters. However, both methods have their advantages and disadvantages, which are highlighted and further discussed in this study.

Multidisciplinary Sensitivity Analysis of the Cooling System of a High-Pressure Turbine Blade in the Pre-Design Phase

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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