Developments on ground blocking implementation in turbulence tool for sonic boom propagation

To support international efforts in certifying potential low-noise civil supersonic aircraft, researchers simulate sonic boom data to validate demonstrators. An important factor of sonic boom propagation is turbulence, certain aspects of which are dependent on the height above the ground. However, the original release of turbulent sonic boom propagation tool KZKFourier incorporates only homogeneous atmospheres. NASA requested that Penn State update KZKFourier to include atmospheric profiling, and an area of interest is ground blocking, as the proximity to the ground influences the shape of turbulent eddies in the atmospheric boundary layer. Penn State has begun implementing a 2D cross spectrum ground blocking methodology into the 3D buoyant vector turbulence spectrum of KZKFourier. Results thus far show that ground blocking, which is significant near the surface, affects a small portion of the sonic boom propagation path beginning at 54,000 ft cruise altitude of interest. [Work supported by the FAA through ASCENT Project 57 under the supervision of Sandy Liu. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the FAA.]