Correlation of HIFiRE-5 Flight Data with Computed Pressure and Heat Transfer (Postprint)
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AEROSPACE SYSTEMS DIRECTORATE
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The HIFiRE-5 test article was an elliptic cone with a 2.5-mm nose radius and 21 aspect ratio and a 7-degree minor-axis half-angle. 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 have been compared to alpha- and beta-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 deg to 5.0 deg, were computed. CFD pressures, normalized with pinfinity, were interpolated to the flight Mach numbers at specified times throughout the ascent and descent trajectories. At each flight time, alpha and beta were estimated from measured pressure by determining the alpha-beta 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 alpha and beta 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.