Since a few years the interest in supersonic travel is increasing and aircraft manufacturing startups are making progress in designing supersonic aircraft. However, certification standards for supersonic civil aircraft have yet to be defined by ICAO (International Civil Aviation Organization). The DLR-project ELTON_SST (Estimation of Landing and Take-Off Noise of SuperSonic Transport) was established to support EASA (European Union Aviation Safety Agency) and the German BMVI (Federal Ministry of Transport and Digital Infrastructure) with scientific data in order to evaluate the noise performance of potential supersonic civil aircraft.
The project is split into two phases. The first phase covers the landing and take-off (LTO) noise estimation based on analytical and empirical models with PANAM (Parametric Aircraft Noise Anaysis Module) and the verification of the models with published data. A one-dimensional engine design is performed based on data published for the NASA 55t STCA (Supersonic Technology Concept Aeroplane) configuration using the GTlab (Gas Turbine Laboratory) software. The level of complexity for the predictions is increased in the second phase of the project by using higher fidelity input data for the PANAM process. RANS (Reynolds-Averaged Navier-Stokes) simulations are performed with the DLR TAU-Code to increase the accuracy of the aerodynamic performance analysis. Default PANAM fan noise calculations are replaced by PropNoise. (Propulsion Noise) simulation results. Acoustic FM-BEM (Fast Multipole Boundary Element Method) simulations are performed to verify acoustic assumptions made in the first phase, for example the reduction of fan noise due to structural shielding. A three-dimensional engine geometry and high-lift devices are designed in this second project phase.
A focus of the analyses is the evaluation of variable noise reduction systems like advanced take-off procedures with a programmed thrust lapse rate and high-speed climb-out. All results obtained in the project are presented in ICAO CAEP (Committee on Aviation Environmental Protection) WG1 (Working Group 1: Noise) and support the discussion of certification standards.
Within ELTON_SST the Institute of Aerodynamics and Flow Technology is applying its extensive tools to predict the aerodynamics, flight trajectories and resulting noise contours of civil supersonic aircraft in increasing fidelity.