Numerical analysis of a linear cascade model for rotor-stator interaction aeroacoustics

Abstract

The rod-airfoil configuration has been widely used to gain more insights into turbulence impingement noise in aeroengines, such as periodic fan wake impingement onto outlet guide vane (OGV). To this scope, this paper investigates a linear cascade model, which replicates the baseline OGV of NASA-Glenn Source Diagnostic Test (SDT) rig. The rod, which is located upstream of the linear cascade, sheds turbulent Kármán vortex street at a frequency equal to the SDT’s first blade passage frequency (BPF). The vertical position of the rod is adjusted to achieve direct impingement of the vortex street along the span of the central blade leading edge. A suitable contraction and test section has been designed to allow freestream flow condition of about 100 m/s. Numerical simulations are performed using Lattice-Boltzmann solver Power- FLOW with the intent of reproducing the whole test rig and get preliminary insights into the aeroacoustics of the test rig before being manufactured. Subsequently, turbulence structures impinging on the OGV are characterized and found to be comparable to those measured in the actual SDT rig. However, the unsteadiness resulting from the rod wake impingement was observed to not only affecting the central blade, but also the neighboring blades and inter-blade channels. This results on a significant influence on the far-field noise characteristics.