Abstract
Advances in trenched-hole film cooling result in a fact that short-holes exposing in a transverse trench have a significantly large potential for application in designs of future double-wall cooled blade. In present work, combined influences of hole-length, trench-depth, compound angle and cooling air flowrate on the film effectiveness and heat transfer features of trenched-holes were discussed deeply. Film effectiveness and heat transfer coefficient were measured by an infrared thermal imaging system. Numerical simulation as an auxiliary tool was conducted to provide necessary flow details. Two typical length-to-diameter ratios of L/D = 2 and 5, three trench-depths of H = 0.5D, 0.75D and 1.0D and two compound-angles of film-hole of 0° and 45° were designed. Cooling air flowrate was controlled in a relatively large range from 0.5 to 4.0 in averaged blowing ratio (BR). The results revealed the various jet-mechanisms caused by L/D while relatively regular variations of turbulent intensity of jets. Thus, the complicated trends in film effectiveness while regular trends in heat transfer coefficient can be clearly captured. The combined influences of trends above can bring to the more undesirable thermal protections for the short-hole jet. The L/D-induced decrement in area-averaged net heat flux reduction (NHFR) can reach 60% at most. To effectively improve film coverage and NHFR, the short-holes were properly embedded in the deeper trench. And the sensitivity analysis of trench-depth to discharge coefficient showed the negligible variation below 5%. The NHFR of the shallowest trench can be improved through application of compound angle, inducing an enlarged aerodynamic loss below 10%.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.