Author(s): Schwab Olivier, Zellmann Christoph, Wunderli Jean Marc
Besides predicting the noise of yearly air operations of an airport, the task to accurately simulate single flight events becomes increasingly important. To that aim, more detailed models consider engine and airframe noise separately, by accounting for thrust, the main engine noise contribution, as well as airspeed and aircraft configura-tion, the main airframe noise contribution. However, for aircraft noise calculations of real operations, the only easily accessible information are usually flight trajectories in the form of radar data. Therefore, the more complex input parameters for aircraft noise calculations have to be estimated. This contribution presents a method to estimate N1, the rotational speed of the engine, which can be used as a proxy for thrust in aircraft noise calculations and which is a typical input for aircraft engine models. The method involves creating take-off and climb N1 profiles as a function of altitude, using physical insights and aeronautical knowledge to account for mass, runway length and thrust settings (such as flex or de-rated settings). In its application, the method does not require specific knowledge of aircraft mass, aerodynamics or any other information except flight trajectories. First results are presented, and the accuracy of the N1 estimation method is discussed in terms of differences between results obtained with true and estimated N1 profiles for single flights at selected receiver points in the near and far field of an airport.
Name: Mr Olivier Schwab