Correlation of HIFiRE-5a Flight Data with Computed Pressure and Heat Transfer

Abstract

The HIFiRE-5 test article was an elliptic cone with a 2.5-mm nose radius and 2:1 aspect ratio and a 7-degree minor-axis half-angle. The vehicle was flown in April 2012. The upper stage of the sounding rocket failed to ignite, resulting in a peak Mach number of about 3 instead of the target of 7. Flight heat flux and pressure data (reduced from almost 300 thermocouples and 50 pressure transducers) have been compared to α-and β-dependent CFD results for pressure distribution, as well as laminar and turbulent heat-transfer results. Computations were performed at three time points in the ascent trajectory. At each time point, five values each of angle of attack and yaw, ranging from-5.0° to 5.0°, were computed. CFD pressures, normalized with p ∞ , were interpolated to the flight Mach numbers at specified times throughout the ascent and descent trajectories. At each flight time, α and β were estimated from measured pressure by determining the α-β combination that minimized the RMS difference between the measured and computed pressures. The vehicle attitude, as determined from measured pressure, was compared to the vehicle attitude derived from Inertial Measurement Unit (IMU) results for α and β from the flight. The two methods showed excellent agreement for the entirety of the ascent and reentry portions of the trajectory. A similar normalization of the laminar and turbulent heat transfer CFD results with St was compared to flight heat transfer measurements, and transition locations were inferred. Finally, a computational heat conduction analysis was made to verify assumptions inherent in the calculation of heat flux from temperature.

First and Fifth Hypersonic International Flight Research Experimentation’s Flight and Ground Tests

“…Low angle-of-attack (AOA) hypersonic transition data were obtained on ascent, and high AOA transition was measured during descent. The HIFiRE-5a mission launched 23 April 2012 from Andoya, Norway [41][42][43][44]. The second stage of HIFiRE-5a failed to ignite, preventing the payload from attaining hypersonic speeds.…”