Numerical study on longitudinal stability for HCW aircraft based on aerodynamic derivatives
Longitudinal stability is one of the most important aspects related to the handling and stability characteristics,flight safety,and flight quality of near-space hypersonic vehicles.At present,most research on longitudinal stability characteristics focuses on the conventional aerodynamic layout with a single-lifting surface.Meanwhile,relevant research on the aerodynamic layout of the new high-pressure capturing wing(HCW)with a double-lifting surface must be strengthened.In this study,the longitudinal aerodynamic derivatives for an HCW aircraft were predicted by combining the small-amplitude forced oscillation,unsteady numerical simulation,and least square methods.Furthermore,the influence of the uncertainties of flight attitude,oscillation parameters,inflow conditions,and center-of-gravity positions on the longitudinal static and dynamic stability characteristics of the HCW aircraft was examined.The results indicate that the longitudinal static stability generally exhibits a trend of weakening fluctuations as the average angle of attack gradually increases from-10° to 14°,while the dynamic stability initially fluctuates slightly and then increases rapidly.Therefore,the larger the oscillation frequency,the stronger the longitudinal stability,but the overall effect is not evident.When the oscillation amplitude is lower than 2°,the prediction results of the aerodynamic derivatives are similar.However,at a larger oscillation amplitude,the hysteresis effect of unsteady aerodynamic forces near the maximum angle of attack is significantly enhanced.Meanwhile,as the flight Mach number increases,the static and dynamic stability are significantly weakened and become more sensitive to a smaller flight Mach number.When the flight altitude increases,the static stability gradually weakens,but the dynamic stability gradually improves,and both become more sensitive to larger flight altitudes.Static stability is greatly influenced mainly by the change of the center-of-gravity position of the aircraft,while the influence on dynamic stability is quite limited.
万方数据
维普
