Fraunhofer-Forschungsgruppe Hydroakustik FHAK

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  • Publication
    Hydrodynamic noise research with a planing boat under acoustical free field conditions
    ( 1991)
    Bartels, F.
    A planing boat has been designed as a tool for research of hydrodynamic noise sources under acoustical free field conditions. The facility is used primarily for investigations of propeller cavitation noise in non-uniform wake flows. The objective of these tests is to disclose the influence of propeller design and wake fields upon cavitation noise. The operational test conditions are the same as for prototype surface ships. Compared to full scale the advance speed or Mach number are the same, but the Reynolds number is lower by the scale factor. The boat is equipped with several devices for observing and recording cavitation and noise. A small acoustic range with a suspended stationary hydrophone is used for recording the radiated far field noise of the test objects.
  • Publication
    Cavitation noise scaling. Status based on NATO RSG. Part 1. Survey of the problems in cavitation noise scaling and prediction
    ( 1991)
    Baiter, H.-J.
    Paper presents a status report on cavitation noise scaling based on work done by a relevant Nato Research Study Group (RSG). The RSG 3 was expected to find out how to improve reliability in predicting cavitation noise from model testing, and how to equalize this reliability for the various model test facilities in use.
  • Publication
    Voraussage von Geräuschen der Propellerkavitation aus Modellversuchen
    ( 1990)
    Baiter, H.-J.
    Nach einigen Anmerkungen über Kavitationsgeräusch folgt ein Überblick über die Probleme, die mit der i.T. genannten Aufgabe verbunden sind. Am Ende wird skizziert, wie weit man heute in der Lage ist, Kavitationsgeräusch aus Modellversuchen vorherzusagen.
  • Publication
    Model tests on noise characteristics of propeller cavitation in wake flow
    ( 1989)
    Bartels, F.
    The paper describes results of propeller cavitation noise experiments in non-uniform wake fields. Two propellers different in design with respect to the dominant type of cavitation have been investigated. The experiments were carried out with a planing boat, designed for cavitation noise research. The boat operates on a lake under acoustical free field conditions. The objective of these tests is to disclose the influence of propeller design and wake fields upon cavition noise.
  • Publication
    On cavitation noise scaling with the implication of dissimilarity inception
    ( 1989)
    Baiter, H.-J.
    Cavitation noise scaling is frequently affected by dissimilarity in cavitation inception. In the literature two approaches have been taken to take this dissimilarity into account. In the present paper an attempt is made to gather theoretical arguments to achieve a better understanding and assessment of these approaches.
  • Publication
    Stochastic models capable of describing the noise produced by unsteady cavitation
    ( 1987)
    Waehrend das Geraeusch stetiger Kavitation als einfache regellose Folge einzelner Geraeuschereignisse aufgefasst werden kann, muss man das Geraeusch unstetiger Kavitation eher als regellose Folge von Ereignistruppen deuten. Es werden stochastische Modelle skizziert, die zur Beschreibung des Geraeuschs unstetiger Kavitation geeignet sind, es werden wichtige Folgerungen aus diesen Modellen erlaeutert und die Vorteile und Grenzen der Modelle werden dargelegt. (IHAK)
  • Publication
    Modulation of high-frequency propeller cavitation noise in a non-uniform wake
    ( 1987)
    Bartels, F.
    Mit dem FHAK-Propellermessfahrzeug "Vitesso" wird das visuelle und akustische Kavitationsverhalten eines 2-fluegeligen Modellpropellers im ungleichfoermigen Nachstrom untersucht. Zur Aufdeckung der Kurzzeit-Struktur des Geraeusches wurden Amplitudenmodulationsspektren sowie auf verschiedene Nachstromsektoren begrenzte Geraeuschspektren herangezogen. (IHAK)