CUED Publications database

A critical examination of a correlation-based transition model for low pressure turbines

Lefas, D and Cui, J and Tucker, PG (2017) A critical examination of a correlation-based transition model for low pressure turbines. In: UNSPECIFIED.

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Two of the main requirements identified for a fully compatible CFD transition model demand that: first it does not affect the underlying turbulence model in fully turbulent regimes and second, that it is applicable to three dimensional flows. The purpose of this paper is to determine whether the γ - Reθ model satisfies these requirements for Low Pressure Turbines (LPTs). The γ - Reθ model’s performance for LPTs is positive overall. A significant improvement on the underlying SST model is observed. The total pressure loss coefficient (Yp) predicted at the exit plane by the γ - Reθ model is only 4% greater than that determined by quasi-DNS, compared to 16% greater for the SST model. In the midspan region, the γ - Reθ model successfully predicts a laminar boundary layer on the suction surface. This laminar boundary layer separates near the trailing edge and then reattaches after transition, resulting in a fully turbulent boundary layer downstream. The location of separation and subsequent separation-induced transition from the γ - Reθ model agrees almost in full with the quasi-DNS results. However, a number of significant limitations are identified, especially in the endwall region. First, γ close to the endwall tends towards zero in the γ - Reθ model, resulting in a zero production of turbulent kinetic energy. Second, even though the laminar region close to the pressure surface is readily identified up to z+ = 14.3, for the higher z-planes examined this is not the case. This contradicts the quasi-DNS results. Finally, the production of turbulence along the suction surface by the corner vortex is significantly underestimated by the γ - Reθ model.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Divisions: Div A > Fluid Mechanics
Div A > Turbomachinery
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:26
Last Modified: 07 Sep 2021 02:14
DOI: 10.2514/6.2017-0782