Flow measurements inside a heated multiple rotating cavity with axial throughflow

This paper discusses experimental results from a multiple cavity test rig representative of a high pressure compressor internal air system. Measurements of the axial, tangential and radial velocity components are presented. These were made using a two component, laser doppler anemometry (LDA) system for a range of non-dimensional parameters representative of engine conditions (Reϕ up to 4 × 106 and Rez up to 1.8 × 105). Tests were carried out for two different sizes of annular gap between the (non-rotating) drive shaft and the disc bores.The axial and radial velocities inside the cavities are virtually zero. The size of the annular gap between disc bore and shaft has a significant effect on the radial distribution of tangential velocity. For the narrow annular gap (dh/b = 0.092), there is an increase of non-dimensional tangential velocity Vϕ/Ωr with radial location from Vϕ/Ωr < 1 at the lower radii to solid body rotation Vϕ/Ωr = 1 further into the cavity. For the wider annular gap (dh/b = 0.164), there is a decrease from Vϕ/Ωr > 1 at the lower radii to solid body rotation further into the cavity. An analysis of the frequency spectrum obtained from the tangential velocity measurements is consistent with a flow structure in the r–ϕ plane consisting of pairs of contra rotating vortices.