Framework for a landing-gear model and acoustic prediction

A new system has been developed at Pennsylvania State University for the prediction of landing-gear noise. The system is designed to handle the complex landing-gear geometry of current aircraft, as well as provide predictions for future aircraft landing-gear designs. The gear is represented by a collection of subassemblies and simple components that are modeled using acoustic elements. These acoustic elements are generic but generate noise representative of the physical components on landing gear. The method sums the noise radiation from each component of the landing gear in isolation, accounting for interference with adjacent components through an estimate of the local upstream and downstream flows and turbulence intensities. The acoustic calculations are made using the landing-gear-model-and acoustic-prediction code, which computes the sound pressure levels at specified observer locations. The method can calculate the noise from the landing gear in isolation or installed on an aircraft for any type of landing gear (main or nose). This paper presents an introduction to the system and initial calibrations by using wind-tunnel experiments and the Aircraft Noise Prediction Program prediction formulas. Noise predictions using the landing-gear model and acoustic prediction are compared with wind-tunnel data for model landing gears of various levels of fidelity and Mach numbers. The initial landing-gear-model-and-acoustic-prediction predictions for dressed configurations show an increase in noise in the frequency range representative of the added landing-gear components. The landing-gear model and acoustic prediction is also compared with wind-tunnel measurements for much larger landing-gear geometry, measured in the Virginia Polytechnic Institute and State University acoustic wind tunnel. Predictions show the ability of the landing-gear model and acoustic prediction to predict the contribution of each component to the overall values. Although the landing-gear model and acoustic prediction is in an early stage of development, the present agreement between the calculations and measurements suggests the method has promise for future application in the prediction of airframe noise.