Operational envelope of a booster venturi Kiel probe at low Mach numbers

Journal article, 2026

Booster venturi Kiel probes combine a shrouded Kiel-type total-pressure channel with a venturi-throat boosted static-pressure tap to provide an internally amplified differential-pressure signal in low-speed flows. This study experimentally characterizes a commercial booster venturi Kiel probe, tested as received, in an open-jet facility over Mach numbers 0.05–0.13 and cone angles up to 50°, and defines its low-speed operational envelope in terms of normalized total-pressure and gain deviations relative to parallel flow. The Kiel-type total-pressure channel retains the expected robustness, within about 1% of its zero-angle value up to cone angles of 35–40°. In contrast, the venturi-based amplification channel satisfies the 1% gain-deviation criterion only within about 5° of the flow direction across all tested Mach numbers. Furthermore, the gain coefficient cp is strongly Reynolds-number dependent in this range, increasing from approximately 2.7 at (Formula presented) to 3.4 at (Formula presented). Two-dimensional yaw–pitch maps show that the off-axis gain response is dominated by an asymmetric venturi-throat static-pressure field, whereas the total-pressure field remains comparatively smooth. These results demonstrate that, at low Mach numbers, booster venturi Kiel probes should be used cautiously within narrow angular envelopes and require careful calibration of the gain coefficient.