The main contribution of the Department for Experimental Methods in this project is to carry out two flight test campaigns using the DLR's Airbus A320 MSN659 as a test carrier. The test campaigns are conducted in cooperation with the following two departments: Experimental Methods (Institute for Aero Elasticity) and for Technical Acoustics (Institute for Aerodynamics and Flow Technology).
Cabin comfort in commercial aircraft depends to a considerable extent on noise present in the cabin. Depending on flight condition and seating position, the predominant contributions to this noise may originate from different sources. The jet engines, the turbulent boundary layer around the fuselage and the airframe noise can excite oscillations of the fuselage, which itself can transmit these oscillations into the air in the cabin interior. The air conditioning is also a significant source of cabin noise.
However, very little is known about either the proportion to which each single noise source contributes to the cumulative sound in the cabin, or about the main propagation path of this sound energy from the external excitement to the emission inside the cabin.
The objective of the flight tests in the SIMKAB project is to provide information on both the intensity of each source mechanism and on the transfer characteristics of the fuselage with respect to each single source. Furthermore, fuselage excitement by the transonic boundary layer, the response of the fuselage structure to this excitement and the emission of noise throughout the cabin are to be measured to provide validation data for the numerical modeling of cabin noise.
Two flight tests with sensors positioned in different sections of the cabin are to be conducted on an Airbus model A320 aircraft. Acoustically relevant sources, sound transmission through the fuselage structure and its reception at the passenger seating positions will be recorded using a mobile acoustic measurement system for flight testing having more than 250 recording channels. By varying flight conditions, the composition of the noise can be varied as well. The effect of each condition on the transfer characteristics can be examined, thereby enabling an analysis of the impact of each sound source on the overall noise at each seating position.