Session: 14-02 Rotating Cavities

Submission Number: 177044

Laminar Turbulent Transition in Axial Compressor Disc Boundary Layers 

In gas turbine high-pressure compressor (HPC) cavities, unsteady buoyancy and rotational effects generate oscillating Ekman layers. The laminar to turbulent transition of these oscillating boundary layers strongly influences heat transfer within the cavity, yet the underlying mechanisms remain poorly understood. Performing direct numerical simulations (DNS) of the full cavity flow is currently infeasible due to the extremely high computational cost, while detailed experimental investigation is also highly challenging.

To address this challenge, the present study investigates a simplified oscillating disk configuration designed to replicate the unsteady behaviour observed in compressor cavities under engine-like conditions. Using a high-order polynomial spectral element CFD solver, oscillatory Ekman layers are simulated under controlled conditions to resolve the transition from laminar to turbulent flow. The study examines the influence of oscillation amplitude, frequency, and both rotational (𝑅𝑒𝜃 = 𝜔 𝑏²/𝜈) and local (𝑅𝑒𝛿 = 𝑉 𝛿/𝜈) Reynolds numbers on boundary layer transition. Depending on the imposed conditions, the results reveal intermittent laminar and turbulent boundary layers with complex temporal evolution. A comparison of disc shear stress with theoretical predictions for laminar and turbulent Ekman layers quantifies the magnitude of the transition effects. It highlights their significance of the transition at high Reynolds number engine conditions.

Presenting Author: Hyder Abedi University of Surrey

Presenting Author Biography: A PhD student at the University of Surrey specializing in Ekman layer transition in rotating cavities and its effects on heat transfer.

Authors:

Hyder Abedi University of Surrey
Diogo Pitz universidade federal do paraná
John Chew University of Surrey
Olaf Marxen University of Surrey