Digitized by Kansas Correctional Industries

Jets in crossflow are used in a wide range of engineering applications and have been studied for more than 60 years. The transversal penetration and structure of a jet placed in a crossflow is known to be strongly three-dimensional. It is believed that, by using a pulsed jet inclined in the crossflow direction, the momentum transport can be controlled in two very efficient ways: the pulse can increase the jet penetration and the mixing downstream, while the inclination avoids the creation of a reverse flow at the jet exit and may extend the mixing area further downstream. Although some results are available in the literature focusing on components of this problem, none addresses the combination of these two factors. Moreover, most of these studies use elaborate flow visualizations and 2-D velocity measurement methods that may not be adequate to elucidate the complexity of such a flow. This study addresses these issues by using stereoscopic PIV measurements for a steady and fully modulated jet at a constant mean velocity ratio, V[subscript r], of 3.4. For the steady jet case, the effect of the jet Reynolds number, Re[subscript j], is investigated. For the pulsed case, the effect of a low pulsing frequency is considered as well as the pulse duty cycle. For each case, the mean three-component velocity field is examined. Proper Orthogonal Analysis (POD) of vorticity and turbulent kinetic energy are used to further evaluate the vortical and turbulent characteristics of the jet. In addition, a vortex detection algorithm, and 3D rendering of the flow streamlines are used to study the near field vortical flow structure of the jet flow. / Graduation date: 2006

Donaldson's single-point second-order model [13] is used to close the Reynolds stress transport equations in cylindrical coordinates. A reduced set of equations are then solved for the decay of axisymmetric vortices and jets. A self-similar solution to the axisymmetric vortices is obtained numerically. The characteristics of the mean flow variables as well as the Reynolds stresses in this solution are discussed. Comparisons of the current results with Donaldson[13J and Donaldson and Sullivan[16] are also presented. The results show that the vortex core is free from turbulent shear stresses. The turbulent kinetic energy is also found to be relatively weak within the core region. The overshoot of the circulation is found to be 5% of the circulation at infinity over a wide range of Reynolds numbers. The effects of Reynolds number on the decay of the vortices are computed and discussed. Some of the quantities, such as mean flow circulation and turbulent kinetic energy, are found to be sensitive to the Reynolds number. However, the overshoot is found to be insensitive to the Reynolds number but its location does. A set of suitable model constants for the axisymmetric jets is also found and a self similar solution for the jet case is obtained. Comparisons of the computed results with some recent experimental data are presented. / Master of Science

A model was developed to predict velocity profiles of radial wall jets produced by ceiling fans and flowing over broiler chickens. Broilers were modeled by balloons with paper cylinders simulating the necks. Wall jet data was recorded for 91.5, 83.8 and 71.1 cm radius fans that were rated at 220, 160, and 108 W, respectively. Each fan was suspended 2.44 m above the floor and operated at four speeds. Applications of the model include 1) calculation of optimum design specifications for ceiling fan applications in broiler houses and 2) prediction of data for managerial decisions concerning existing ceiling fan applications. Model inputs are the fan radius and the characteristic velocity. The characteristic velocity was defined as the maximum air velocity 30 cm below the blades. The wall jet model was interfaced with a broiler growth model for heat stressed broilers to simulate summer conditions and to predict the additional weight gain due to the wall jet. Also, the wall jet was developed to predict the air velocity near the litter to aid litter management decisions. Ceiling fan applications in the southeast, used in conjunction with the summer model, have the potential of increasing summer broiler production by 10% and decreasing fan energy consumption by 8 to 12%. The model may be used to optimize the benefit to the producer. / Ph. D.