Attainment of high turbo-compressor aerothermodynamic performance requires very small rotor tip clearance which also helps keep low noise levels. Non-uniform rotor-stator tip clearance in a turbocompressor is a source of acoustic annoyance to pilots. Depending on the degree of nonuniformity of the tip clearance, a characteristics noise known as 'grinding' arises from the blade tips forming nearly 60 to 75 percent of the total compressor noise. Besides, periodic longitudinal play of the compressor gives rise to resonance. A physical model has been proposed in this paper for explaining both 'grinding and resonance' from the blade tips of rotor blades with excessive tip clearance. The paper highlights the importance of maintaining uniformity of compressor and fan blade tip clearance within narrow limits to eliminate the distracting noise which causes annoyance and pilot fatigue. An equation has been derived for the intensity of the grinding noise and the noise due to compressor tip clearance. Pilot opinion surveys on the qualitative rating of grinding and resonance show good correlation with the observed amplitude levels of these signatures. (Peters)


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    Title :

    Noise generated from non-uniform clearance of turbo-compressors and fans of aircraft


    Additional title:

    Geraeuschentwicklung durch ungleichmaessiges Spiel in Turboverdichtern und Flugzeuggeblaesen


    Contributors:

    Published in:

    Publication date :

    1979


    Size :

    5 Seiten, 4 Bilder, 5 Tabellen, 3 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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