Characterisation of Unsteady Flows in Centrifugal Impellers

Ramamurthy, S and Murugesan, K (1991) Characterisation of Unsteady Flows in Centrifugal Impellers. In: 6th National Convention of Aerospace Engineers, 24 & 25 January 1991, IIT,Bombay. (Submitted)

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    Abstract

    The flow at centrifugal impeller outlet is non uniform across the blade pitch and unsteady with reference to time. An attempt was made to measure the flow field at impeller outlet using a hot wire sensor. A hot wire sensor placed very close to the impeller tip was used in two angular positions to measure radial and whirl components of velocity in a dynamic mode across the blade to blade pitch at the mid channel. The hot wire signal was recorded in a phase locked manner to get an ensemble average of the signal for four revolutions. A method was evolved for approximate analysis of hotwire measurements and to characterise by flow at impeller outlet. The measured velocity with time was converted to ppsition.wise, indicate that the highly unsteady and the' flow %t a given location is picked up more than once within aGsingle sweep of the passage. The flow at these points has a vobtex motion of changing angular direction with respect to time. The variation of velocity at a given angular location with respect to time was calculated assuming symmetry of flow in each passage from the measured velocity with respect to time. The calculation indicate that the flow within the passage is disturbed by secondary vortices shed within the passage into the flow at periodic intervals of approximately three times in each revolution.

    Item Type: Conference or Workshop Item (Lecture)
    Uncontrolled Keywords: Hot wire, centrifugal impeller,
    Subjects: AERONAUTICS > Aerodynamics
    AERONAUTICS > Aircraft Propulsion and Power
    Division/Department: Propulsion Division, Propulsion Division
    Depositing User: Dr S Ramamurthy
    Date Deposited: 10 Aug 2010 13:34
    Last Modified: 10 Aug 2010 13:34
    URI: http://nal-ir.nal.res.in/id/eprint/8916

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