Conjugate Heat Transfer Simulation and Experimental Validation of a Dual-Shielded Air Temperature Probe at Subsonic and Transonic Speeds

Accurate total air temperature measurement is a fundamental requirement in aerospace and aerodynamic applications, particularly within high-speed wind tunnels. This paper presents the comprehensive design, Conjugate Heat Transfer (CHT) analysis, and experimental validation of a novel, low-cost dual-shielded Resistance Temperature Detector (RTD) probe specifically engineered for the subsonic to transonic speed range (0.2 ≤ Ma ≤ 0.9). The research addresses a critical gap by providing a fully validated, cost effective alternative to traditional measurement devices in this regime. High-fidelity CHT simulations were employed to analyze the coupled heat transfer mechanisms governing the probe’s performance. Numerical results conclusively demonstrate that the velocity error is the dominant component of the total measurement error, consistently accounting for over 75% of the total deviation. Crucially, the engineered dual-shield structure successfully suppresses conduction error, which remained below 1 K across the entire test matrix. Flow analysis further revealed the onset of a choked flow phenomenon at the probe's outlet vents at approximately Ma = 0.8. This choking is interpreted as a vital error stabilization mechanism, as it fixes the internal mass flow rate, thereby preventing a non-linear increase in velocity error at higher transonic speeds. Experimental validation performed in a specialized wind tunnel confirms the high accuracy of the CHT predictions, validating the probe’s stability and suitability for reliable high-speed temperature measurement.