JET NOISE

Issue Table of Contents

ESDU CFD Guides

Shafts with Interference - Fit Collars

Dynamic Characteristics of Cylindrical Helical Springs

Jet Noise

Low-Cycle Fatigue of Stainless Steels

Three Peaks Challenge

Aircraft Drag

The Aircraft Noise and Structural Dynamics Group has recently issued amendments to three jet exhaust noise prediction Data Items and the associated software.

ESDU 98019, which contains a computer-based estimation procedure for single-stream, far-field jet noise now offers the user the option of using a database modified especially for ESDU by the Institute of Sound and Vibration Research (ISVR) in Southampton, U.K. Use of this database can provide better agreement with measured data. In addition, the extrapolation procedure used within the methods has been improved to make it both more accurate and more robust.

We have taken the principles behind the improvements to the extrapolation procedure and applied them to both ESDU 01004, which can be used to predict far-field coaxial jet noise, and to ESDU 99006, which is applicable to near-field, single-stream jet noise.

These prediction methods work by interpolating and extrapolating data from a database. The computer programs may be run using the provided databases or a database generated from the user’s own data. These databases need not be restricted to data for just jet exhaust noise but could include installation effects as well as other components of engine noise. The computation involves a least-squares surface fitting procedure that may be of bi-linear or bi-quadratic form. Appropriate weighting of the data is included.

The Aircraft Noise Group is intending to issue an Item on turbine noise in 2008.

Queries regarding this article should be directed to Dr Cyrus Chinoy, Head of the Aircraft Noise and Structural Dynamics Group: cyrus.chinoy@ihs.com

For more information visit www.esdu.com.