Complex landing gear noise prediction using a simple toolkit

This paper describes the initial development of a method for the prediction of the noise radiated by aircraft landing gear. Called the Landing Gear Model and Acoustic Prediction (LGMAP), it will eventually include all the geometric complexity of a realistic landing gear. This will be achieved by dividing the gear into a number of elements or objects. The noise from each of these elements is described by a simple acoustic model. Each object has three attributes; its geometry and location, and an upstream and downstream environment. This enables the flow or noise from one element to interact with any other. The method is designed to allow improved element acoustic models to be introduced as they become available. This paper contains some initial examples for two objects; a cylinder element and a wheel model. The landing gear is divided into assemblies made up of these elements. The radiated noise is calculated in the time-domain using a source-time-dominant solution to the Ffowcs Williams-Hawkings equation. This initial, rather crude, model is calibrated by comparison with experiment and existing noise prediction methods. The purpose of this paper is primarily to introduce the modeling philosophy rather than make extensive predictions. Though more than one example is given. The model is still in its early development stages and many important acoustic mechanisms are not included. Some of the future plans and necessary extensions to the model are discussed.