## LSU Historical Dissertations and Theses

1989

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

#### Department

Mechanical Engineering

George D. Catalano

#### Abstract

An experimental and computational investigation is made for the turbulent flow field generated by a jet discharging transversely into a confined moving stream. For jet to cross flow mean velocity ratios (R) equal to 2 and 4, measurements are made using a laser-Doppler velocimeter (LDV) in conjunction with a tracker processor. Quantities measured include mean velocities, turbulence intensities, turbulent shear stress, and dissipation rates of the turbulent kinetic energy. The jet flow Reynolds numbers investigated are 1.5 $\times$ 10$\sp4$ for R = 2 and 3.0 $\times$ 10$\sp4$ for R = 4. The structured nature of the turbulent flow field is documented from the statistical measurements. The autocorrelation functions are calculated from the instantaneous velocities using a direct Fourier transform method. The auto-spectral density functions are calculated via a Fast Fourier Transform of the autocorrelation functions. The integral length scale and the Taylor microscale are calculated from the autocorrelation functions using the Taylor hypothesis. The probability density function, skewness and flatness factors are calculated from the randomly sampled instantaneous velocities. For the velocity ratios (R) equal to 2, 4 and 6, calculation results are obtained by solving the steady, three-dimensional elliptic forms of the Reynolds time-averaged equations. The finite-difference solution scheme is employed for the calculation procedure. The Reynolds stresses appearing in the time-averaged equations are calculated from the two equation k $-$ $\epsilon$ model of turbulence.

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