ANALYSIS OF APPLICATION METHODS OF THE TONALITY AMENDMENT DURING GAS-TURBINE ENGINES DEVELOPMENT TESTS FOR CORRESPONDENCE WITH NOISE ENVIRONMENTAL REQUIREMENTS

Abstract

The important and actual task of the modern engine engineering is an objective estimation of gas-turbine engine noise levels during its development tests, which will allows to estimate the expected noise levels as part of aircraft. The problem is under review, whose content consists in the analysis of application methods of the tonality amendment during gas-turbine development tests for correspondence with environmental requirements.

Classification of tonal noise is contained in many sources. Unfortunately, the determinations and criteria, provided there, are not always consistent with one another that indicate uncomplete determination processes of influence of tonal noise component on its sanitary-hygienic evaluation. The ecological properties of the signal are affected by the modulation law of its tonal (frequency) components. Tone signals of a constant frequency with a unit amplitude modulation index are recognized by the central nervous system as a pure tone and cannot be defined as adverse. These signals, during gas-turbine development tests, include all components parts of the engine that rotate with the constant circular frequency.

It is shown that the application of the method of spectral analysis for signals with not determined parameters of stability, leads to undefined methodical error which is not taken into consideration in traditional methods. Determining the value of the tonality parameter, which defines the amendment of the deterioration of object noise assessment, is not strictly validated and is random. In accordance with the foregoing analysis, in our opinion, it is necessary to adjust traditional methods of environmental certification of aircraft on noise level. The methodology should involve the identification of neutral (the summary parameter is not adjusted), unfavorable (the summary parameter is adjusted to the downside) and favorable (the summary parameter is adjusted in the direction of improvement) noises.

The ranking algorithm, in connection with the application of the result to biological objects, can be intellectual and identical to the function of Wernicke's area of the central nervous system, i.e. the calculation of mutual correlation function or the correlation coefficient of the signal noise of the aircraft with the database of "favorable" or "unfavorable" signals.