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Proceedings of the 25th National and 3rd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2019)

ISBN Druckformat: 978-1-56700-497-7 (Flash Drive)
ISBN Online: 978-1-56700-496-0

AN EXPERIMENTAL STUDY OF MIST ASSISTED FILM COOLING ON A FLAT PLATE

DOI: 10.1615/IHMTC-2019.590
pages 347-352

Mallikarjuna Rao P
Department of Mechanical Engineering, Indian Institute of Technology Madras

Bhamidi V. S. S. S. Prasad
Thermal Turbomachines Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India

Abstrakt

To increase the film cooling performance of a gas turbine cooled blade, a noval mist assisted air film cooling scheme is proposed by wang et al. [1]. This scheme is further investigated experimentally in this paper to determine the effect of blowing ratio. Tiny water droplets in the mist, characterized by Rosin Rammler mean diameter of about 36.7 µm measured with a PDPA system, are introduced into the cooling air for a flat plate mounted in a wind tunnel test facility. The effectiveness values are evaluated for the mist assisted film cooling and compared them against 'air-only' film cooling. Results show that after mist is added into coolant air, the cooling effectiveness is noticeably higher. Moreover, the coolant coverage is much better in both the stream wise and the span wise directions. At blowing rates (0.55) the coolant jets spread on the wall surface immediately after exiting the holes. This results in a high effectiveness peak close to the ejection location. The small coolant mass flow is diluted fast by the hot gas flow and, therefore, a decay of the maximum effectiveness downstream of the test plate.