Abstract
In order to deepen the understanding of rotating effects on internal cooling, the flow and heat transfer characteristics of 2-pass rotating rectangular smooth/ribbed channels are investigated by Reynolds-Averaged Navier-Stokes (RANS) simulation. Three rotating numbers (Ro = 0.10, 0.25, and 0.40) are simulated, and the maximum buoyancy parameter (Bo) reaches 5.0. The results show that the rotating buoyancy has significant effects on the flow and heat transfer under high Bo conditions. When Bo > 1.0, rotating buoyancy inducts flow separation near the leading edge (LE) in the first passage, while the air flow in the second passage shows a double-peak profile. With increased Bo, the heat transfer in the first passage is greatly increased, and the maximum growth rate occurs at Bo = 0.6~1.0. However, the heat transfer in the second passage has no obvious changes due to a strong turn effect. In the ribbed channel, rotating effects are much weaker than those in the smooth channel. This research helps to improve the understanding of the internal cooling heat transfer mechanism in land-based gas turbines under typical operating conditions.
Highlights
Gas turbines are widely applied in landed power generation, aircraft propulsion and other fields
A possible reason is that the temperature distribution in the tip turn region is complicated and region-averaged temperature measured by thermocouples and copper plates has larger uncertainty
Velocity Distribution in Meridian Planes by high rotating buoyancy exists near leading edge (LE)
Summary
Gas turbines are widely applied in landed power generation, aircraft propulsion and other fields. Dimples and ribs to increase turbulence is one of the most effective ways to enhance heat transfer [2,3]. The rotating effects on internal cooling have received increased attention. Based on Bo, the convective heat transfer inside a turbine blade can fall into the regime of natural convection (Bo > 10), mixed convection (0.1 < Bo < 10), and forced convection (Bo < 0.1). Bo of an in aero-engine and a land-basedoperate gas turbine show internal cooling convec tinctly different nature. Aero-engines operate at Bo of 0 to 0.25 and forced condominates.
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