Heat transfer measurements of a nanoscale hot-wire in supersonic flow

Upon its development and initial characterization, the supersonic variant of the nanoscale thermal anemometry probe (S-NSTAP) was deployed in a supersonic wind tunnel facility, where both freestream and boundary layer measurements were obtained at M_∞ =2 . The low operating stagnation pressures generated reliable data, where the effects of Reynolds number, Mach number and overheat ratio on the sensor’s heat transfer were investigated in detail. The performance of the S-NSTAP was also compared to that of a conventional cylindrical hot-wire and the S-NSTAP was shown to exhibit unparalleled temporal resolution ( ∼ 300 kHz). The mass flux sensitivity coefficient of both hot-wires was further computed and appeared to vary between probes, yielding a coefficient twice as large for the conventional probe than for the S-NSTAP. The experimental data obtained from both hot-wires were also compared, via spectral analysis and turbulence statistics, to the results of a numerically modelled turbulent boundary layer. Graphic abstract