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Innovating turbine cooling

The START Lab evaluates advanced turbine cooling designs and methods

Effusion Cooling in Combustor Liners

Effectively cooling combustion chamber walls is necessary to increase durability in modern gas turbines as firing temperatures continue to increase. Recent research at START has evaluated the overall effectiveness and turbulence level of different effusion cooling patterns near the dilution holes, where the flow field is most complex due to the interaction between the effusion and dilution jets. Results show that an outward facing effusion geometry was able to improve cooling effectiveness near the dilution holes as well as further downstream.

Cooling effectiveness data for a combustor liner with dilution holes and film-cooling holes (top) as well as the flowfield measurements of the dilution jet with liner film-cooling holes.

Particle Deposition in Turbine Cooling Configurations

Particle ingestion is a growing problem in jet engines, especially with the increasing number of flights in areas of the world with denser atmospheric particle concentration.  In many cases, these ingested particles can to cover and block cooling schemes within different areas of the jet engine, possibly leading to part burnout and premature failure.  The effects of dirt introduction method on particle deposition were investigated.  A novel continuous feed mechanism was developed for comparison against a particle introduction method of discrete bursts of dirt, referred to as slugs.

Particle deposition on an effusion plate; deposition in white and the effusion plate surface in black.

Numerically Optimized Wavy Channels

Complex cooling schemes will make their way into gas-turbine engines as advancements are made in additive manufacturing. Research was conducted at START to optimize wavy channels to minimize pressure loss and maximize heat transfer, two critical aspects of turbine cooling. It was learned that optimization was possible for shorter wavelengths while longer wavelengths proved problematic. In these shorter wavelength channels slight changes in channel shape affected the downstream flow patterns.

Branched, wavy channels that have been optimized for pressure drop and heat transfer.

 

Film Cooling

Literature contains many different shaped hole designs, however few geometries are common between publications of different researchers. Most published film cooling studies compare novel cooling hole designs to the performance of a cylindrical hole, which is not necessarily the most helpful standard given the well-known jet detachment that occurs at high momentum flux ratios. Designers and researchers would benefit from defining a baseline shaped hole geometry to be used instead of cylindrical holes for comparison purposes. At PSU ExCCL we performed a literature review that identified over 120 different shaped hole geometries. We then designed a public, baseline shaped hole representative of geometries in literature. The resulting public baseline is the “7-7-7 shaped hole” geometry.

The Public Shaped Hole is a laidback fan-shaped design