Installing 5-hole probes for turbine blade surface flow measurement requires precise positioning to capture accurate pressure and velocity data without disturbing the flow or damaging the blade.Sensor Calibrationwelcome to click on the website to learn more!
The optimal mounting location is 20-30% of the blade chord from the leading edge, where flow separation is minimal and pressure gradients are stable. A wind tunnel test comparing positions found readings at 25% chord had 2% less variability than those at 10% (near the leading edge, prone to turbulence) or 50% (where flow acceleration distorts data).
Probe tip distance from the blade surface is critical—1-2mm is ideal. Closer than 1mm risks contact during blade vibration, while farther than 2mm captures flow unaffected by the blade’s boundary layer. In a gas turbine test, a 1.5mm gap provided data 3% closer to computational fluid dynamics (CFD) predictions than a 3mm gap.
Angle alignment must match the blade’s camber. Probes tilted 5° from the blade’s local surface angle introduced 4% error in flow angle measurements, as observed in a calibration test. Using adjustable mounts with ±1° fine-tuning ensures proper alignment.
For rotating blades, wireless, battery-powered probes eliminate cable interference. A steam turbine test found wired probes caused 5% higher drag on rotating blades, while wireless models had negligible impact, improving data accuracy.