Predicting Noise-Power-Distance Tables for the REBEL-C Blended Wing Body Aircraft

Abstract

Aircraft noise reduction is required to mitigate the noise nuisance around airports. Blended wing body (BWB) designs promise lower noise emissions through their engine location. The aircraft design is characterized by its wing-fuselage integration, with both the wings and the fuselage acting as lifting bodies. Mounting engines on top of the fuselage reduces engine noise through shielding. Best-practice models make use of noise-power-distance tables to compute noise quickly for multiple events. These tables are generated using measurements obtained during noise certification procedures. This thesis aims to predict the noise-power-distance (NPD) tables for the REBEL-C blended wing body aircraft. The semi-empirical noise modeling program SOPRANO was used to develop a method to calculate NPD tables for conceptual aircraft. Good agreement was shown between NPD tables determined using measurements and SOPRANO for three conventional aircraft with an average root-mean-square error of 2.8 dBA or less for LAmax. Thrust settings of the REBEL-C were determined using the flight profile of the A320-214 reference aircraft and by assuming equal thrust-to-weight ratios. Attenuation resulting from the engine noise shielding model using Kirchhoff’s theory of diffraction was implemented into SOPRANO. The noise metrics of the REBEL-C show significant lower noise compared to an A320. Reductions of -6.3 to -21.8 dBA were seen for LAmax during departure. For approach, the differences are smaller due to the airframe dominance. Engine shielding reduces the engine noise of the BWB by such high levels for equal T/W ratios that the departure noise metrics are lower than the approach metrics. The methodology developed during this project looks promising to predict NPD tables for conceptual aircraft, although it is recommended to carefully consider the semi-empirical noise models that are used.