CUED Publications database

Bleed and vortex generator effectiveness for separation prevention in a transonic diffuser

Oorebeek, JM and Babinsky, H (2014) Bleed and vortex generator effectiveness for separation prevention in a transonic diffuser. In: UNSPECIFIED.

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Abstract

An experimental study was performed to characterize the effect of flow control on the separated flow within a transonic diffuser. Mach 1.348 inflow at a Reynolds number of approximately 20 × 10 6 entered diffuser with a 6° slope to the floor. The baseline flow exhibited poor diffuser performance, reaching a static pressure rise of 46% of the predicted inviscid rise, and having a fully separated flow within the diffuser. The shock motion was not constrained, and Xrms was approximately equal to the baseline boundary layer thickness. Flow control was applied through 3 pairs of 3mm high ramped-vane vortex generators, or through suction across a distributed array of normal bleed holes with either 1mm or 2mm diameter. All forms of flow control were found to be effective at improving diffuser performance, with VGs increasing the static pressure to 63% of the inviscid rise, and suction through 1mm holes in the diffuser saw the static pressure increase to 80% of the inviscid pressure rise. Suction upstream of the diffuser entrance was found to produce a similar maximum pressure rise to that of VGs. Overall, VGs acted similar to boundary layer suction removing 15 - 20% of the floor boundary layer. Combinations of the two methods allowed for improvement similar to the high suction rates, while requiring 15% less of the boundary layer to be removed.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Subjects: UNSPECIFIED
Divisions: Div A > Fluid Mechanics
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:16
Last Modified: 10 Aug 2017 01:37
DOI: