Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.
(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)
A semi-analytical model of turbulent jets injected into a cross-flow
Abstract
This thesis describes the mixing of a single jet discharged into a free stream, or a row of jets discharged normally into a confined cross flow. Flow configurations of this type are relevant to the primary and dilution zones of gas turbine combustors. A better understanding of this process can provide more effective design for the dilution air process in gas turbine combustion systems. A finite element numerical procedure is used to solve governing partial differential equations for velocity, temperature, pressure, turbulent kinetic energy and energy dissipation rate. The accuracy of the results, obtained using the k-$\varepsilon$ turbulence model, is discussed and compared with the experimental data. The results have a good quantitative agreement with the existing experimental data. Quantitative differences exist and are due to both the numerical diffusion and turbulence model error. By applying the entrainment theory, and simple assumptions about self-similarity on a section across the jet, a general asymptotic form of the jet temperature centerline trajectory is obtained. The solution has the same form as is predicted by the integral analysis of the jet in a cross flow. Using results from the numerical calculations, the entrainment coefficient is calculated. The entrainment coefficient is then used to determine the asymptotic form of the temperature centerline trajectory, which is compared with the calculations. Results are presented for the jet-to-main-stream velocity ratios of 2.3 and 3. The three main-stream-to-jet temperature differences used for each geometry are 100$\sp\circ$C, 500$\sp\circ$C and 1000$\sp\circ$C. In the case of confined flow, channel heights of four and eight jet diameters, and spacing between adjacent jets of four jet diameters is used. Better agreement between the calculations and analytical predictions is obtained for lower temperature differences, and for a free jet in a cross flow. The results for the confined jet show that the $\rm {z\sim x\sp{1/3}}$ law predicts the jet temperature centerline trajectory over the whole flow field much more accurately. The results also suggest that the geometric characteristics of the problem play a significant role and need to be included in the development of the trajectory expressions.
Subject Area
Mechanical engineering|Computer science
Recommended Citation
Kosanovic, Dragoljub B, "A semi-analytical model of turbulent jets injected into a cross-flow" (1996). Doctoral Dissertations Available from Proquest. AAI9619401.
https://scholarworks.umass.edu/dissertations/AAI9619401