Conventional gas turbines are a very mature technology and performance improvements are becoming increasingly difficult and costly to achieve. Pressure Gain Combustion (PGC) has emerged as a promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine cycles. Generally, pressure gain combustion is realized with approximations of constant volume combustion and with detonative combustion. Previous cycle analyses that considered standard turbine cooling methods have shown that the application of pressure gain combustion in gas turbines may require  more turbine cooling air flow. This change has a direct impact on the cycle efficiency and reduces the possible efficiency gain that can potentially be harvested from the new combustion technology. Novel cooling techniques could change this and unlock an existing potential for a further increase in efficiency. Such a novel turbine cooling approach is the application of pulsating impinging jet in the inner side of the turbine blades.

 

The current work is divided in two parts. In the first part, experimental results of pulsating impingement cooling system are presented. The potential of this novel cooling approach to increase the convective heat transfer in the inner side of turbine blades is demonstrated. Nusselt number measurements from experiments performed in a dedicated experimental facility are presented for various values of pulsation frequencies and stand-off distances. The second part of the work builds on the best results of the aforementioned experiments and presents a cycle analysis model that incorporates the effect of the higher Nusselt number on the turbine cooling air flow requirement. The influence of this change on the overall cycle efficiency is shown by comparing the new cooling technology with standard convective cooling methods.


Pulsed Impingement Turbine Cooling and its Effect on the Efficiency of Gas Turbines With Pressure Gain Combustion

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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