The results of an experimental investigation of triangular and circular jets of air issuing into still-air surroundings are presented. Two isosceles triangular jets, issuing from sharp-edged orifices with apex angles of 30 and 160 deg, a sharp-edged orifice circular jet, and a contoured nozzle circular jet, were used for the study. The orifices and nozzle had the same exit area. The Reynolds number, based on the equivalent diameter of the triangular orifices (or diameter of the circular orifice or nozzle), was ( 1.68 ± 0.08 ) × 10 5 in the jets. An x–array hot-wire probe and a pitot-static tube were used to acquire the data. The results show that the 160 deg triangular jet has a higher mean streamwise centerline velocity decay rate but a lower mass entrainment rate than the 30 deg triangular jet. Also, the preferred mode Strouhal numbers for the 160 and 30 deg triangular jets were found to be 0.96 and 0.53, respectively. The autocorrelation coefficient distribution exhibits long tails in the 160 deg triangular jet, but it is periodic in the 30 deg triangular jet. Contour maps of the mean streamwise velocity, from which a faster development of the 160 deg triangular jet can be deduced, show changes in the shape of the triangular jets.


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    Title :

    Mean Streamwise Centerline Velocity Decay and Entrainment in Triangular and Circular Jets


    Contributors:
    Quinn, W. R. (author) / Azad, M. (author) / Groulx, D. (author)

    Published in:

    AIAA Journal ; 51 , 1 ; 70-79


    Publication date :

    2012-11-22


    Size :

    10 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English