Evaluating the Assumptions in an Empirical Jet-Surface Interaction Noise Model

Brown, Clifford A.

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NASA NTRS · 20180004583

Evaluating the Assumptions in an Empirical Jet-Surface Interaction Noise Model

Brown, Clifford A.

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Abstract

A set of empirical jet-surface interaction noise models, developed for single-stream round nozzles exhausting over a simple surface in a static ambient, are evaluated for use in more realistic applications that include multi-stream nozzle systems, multi-plane surface geometries, and a flight-steam. The simple-single-stream models have several advantages when used in system-level noise studies: they are robust, they are quickly computed, and they are generally applicable to a wide range of configurations. However, these models require simplifying assumptions when applied to more complex jet exhaust systems; for example, previous work on multi-stream jets used an empirical formula to compute a single-stream equivalent jet potential core length that could be used to predict the noise using simple-single-stream jet-surface interaction models. This paper considers the effect of flight and multi-plane surfaces using a similar approach: introducing assumptions to simplify the complex system, applying the simple-single-stream models, and evaluating the uncertainty.

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Brown, Clifford A.. 2018-01-08. Evaluating the Assumptions in an Empirical Jet-Surface Interaction Noise Model. https://ntrs.nasa.gov/citations/20180004583

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