The first stage of turbine in a Brayton cycle faces the maximum temperature in the cycle. This maximum temperature may exceed creep temperature limit or even melting temperature of the blade material. Therefore, it becomes an absolute necessity to implement blade cooling to prevent them from structural damage. Turbine inlet temperatures for oxy-combustion supercritical CO~2~ (S-CO~2~) are promised to reach blade material limit in near future foreseeing need of turbine blade cooling. Properties of CO~2~ and the cycle parameters can make Reynolds number external to blade and external heat transfer coefficient to be significantly higher than those typically experience in regular gas turbines. This necessitates evaluation and rethinking of the internal cooling techniques to be adopted.

The purpose of this paper is to investigate conjugate heat transfer effects within a first stage sCO~2~ turbine linear cascade. This study can help understand cooling requirements which include mass flow rate of leakage coolant S-CO~2~ and geometry of cooling channels. Estimations can also be made if the cooling channels alone are enough for blade cooling or there is need for more cooling techniques such as film cooling, impingement cooling and trailing edge cooling. The conjugate heat transfer and aerodynamic analysis of a turbine cascade is carried out using a commercial computational code, STAR CCM+. Two cases of turbine inlet temperature are considered for the study considering future potential needs (i) 1350 K and (ii) 1775 K. Working fluid is a mixture of CO~2~ and H~2~O with higher fraction of CO~2~ as observed in oxy-combustion sCO~2~ cycle. Thermo-physical properties of this mixture are given as input to the code in form of tables using REFPROP database. The vane material considered is Inconel 718. Thermal conductivity of Inconel is given as input to CFD code as a polynomial function of temperature.


A Numerical Study on Conjugate Heat Transfer for Supercritical CO2 Turbine Blade With Cooling Channels

Division / Sponsor:
International Gas Turbine Institute (IGTI)

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

Turbo Expo - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.