Transdisciplinary Research for Silent Supersonic Aircraft by Integrating Computation and Experiment

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One of the fundamental problems preventing commercial transport aircraft from supersonic flight is the generation of strong sonic booms. The strength of the shock waves generated by an aircraft flying at supersonic speed is a direct function of both the aircraft's weight and its occupying volume; it has been very difficult to sufficiently reduce the shock waves generated by the heavier and larger conventional supersonic transport (SST) configuration to meet acceptable at-ground sonic-boom levels.Our team first re-analyzed the classic Busemann biplane configurations to understand its basic wave cancellation concept using modern Computational Fluid Dynamics (CFD) tools. We then designed a two-dimensional (2-D) supersonic biplane that not only shows the desired aerodynamic characteristics at its design condition, but also outperforms a zero-thickness flat-plate airfoil. (Zero-thickness plat-plate airfoils are known as the most efficient monoplane airfoil at supersonic speeds.) Also we studied biplane performance not only at their design Mach numbers but also at off-design conditions. We extended the analysis to 3-D wing configurations as well.In parallel to the computational studies, we carried out series of experiments. The first experiment conducted here was the sonic boom experiment using gas gun. The N-wave was captured successfully. The second experiment was the 2 D wind tunnel test using Indraft Wind Tunnel Facility newly constructed in this research. In addition, conventional wind tunnel tests were conducted using existing wind tunnels. These experiments revealed important off-design flow features to be further studies by using CFD.The main research result is the development of the supersonic biplane theory. Biplane configuration allows canceling shock waves created by supersonic objects. It can be unconventional and innovative concept for future supersonic transport.