RANS models in CFD are used to predict the liner wall heat transfer characteristics of a gas turbine annular combustor with radial swirlers, over a Reynolds number range from 50,000 to 840,000. A three dimensional hybrid mesh of around twenty five million cells is created for a periodic section of an annular combustor with a single radial swirler. Different turbulence models are tested and it is found that the RNG k-e model with swirl correction gives the best comparisons with experiments. The Swirl number is shown to be an important factor in the behavior of the resulting flow field. The swirl flow entering the combustor expands and impinges on the combustor walls, resulting in a peak in heat transfer coefficient. The peak Nusselt number is found to be quite insensitive to the Reynolds number only increasing from 1850 at Re=50,000 to 2200 at Re=840,000, indicating a strong dependence on the Swirl number which remains constant at 0.8 on entry to the combustor. Thus the peak augmentation ratio calculated with respect to a turbulent pipe flow decreases with Reynolds number. As the Reynolds number increases from 50,000 to 840,000, not only does the peak augmentation ratio decrease but it also diffuses out, such that at Re=840,000, the augmentation profiles at the combustor walls are quite uniform once the swirl flow impinges on the walls. It is surmised with some evidence that as the Reynolds number increases, a high tangential velocity persists in the vicinity of the combustor walls downstream of impingement, maintaining a near constant value of the heat transfer coefficient. The computed and experimental heat transfer augmentation ratios at low Reynolds numbers are within 30-40% of each other. / Master of Science

A comparison study between axial and radial swirler performance in a gas turbine can combustor was conducted by investigating the correlation between combustor flow field geometry and convective heat transfer at cold flow conditions for Reynolds numbers of 50,000 and 80,000. Flow velocities were measured using Particle Image Velocimetry (PIV) along the center axial plane and radial cross sections of the flow. It was observed that both swirlers produced a strong rotating flow with a reverse flow core. The axial swirler induced larger recirculation zones at both the backside wall and the central area as the flow exits the swirler, and created a much more uniform rotational velocity distribution. The radial swirler however, produced greater rotational velocity as well as a thicker and higher velocity reverse flow core. Wall heat transfer and temperature measurements were also taken. Peak heat transfer regions directly correspond to the location of the flow as it exits each swirler and impinges on the combustor liner wall. Convective heat transfer was also measured along the liner wall of a gas turbine annular combustor fitted with radial swirlers for Reynolds numbers 210000, 420000, and 840000. The impingement location of the flow exiting from the radial swirler resulted in peak heat transfer regions along the concave wall of the annular combustor. The convex side showed peak heat transfer regions above and below the impingement area. This behavior is due to the recirculation zones caused by the interaction between the swirlers inside the annulus. / Master of Science

A burner is very important device in process furnaces that significantly affect the production of emissions during the combustion process. One of the key things in development of the modern low-NOX burners is the evaluation of flow field downstream of an axial blade swirler inside the burner. The computational fluid dynamics (CFD) is often used to predict the attributes of the flow. Predicted values should be validated with measurement. It is the reason why the velocity fields for several choosen swirlers were measured. The hot wire anemometry was choosen and the dual-sensor probe was used during the measurement. The data can be then used for CFD validation. This thesis describes procedure of measurement set-up. The experimental facility was designed according to the anemometry method. The new probe traversing system was designed, which provides desired accuracy. Five different swirlers were measured. Large data set, need for customized post-processing and control over calculation procedures lead to new software design. For each swirler the velocity profiles were gathered and the swirl numbers calculated. That final data were transferred in to graphical format. Uncertainty of measured data was calculated. Results show counter-rotating flow in some areas closed to the swirler. Some drawbacks of current measurement set-up are discussed. Based on the thesis reader can obtain the information and knowledge for consequent measurements of swirl burners velocity profiles.

La trempe à l’air est largement utilisée dans les procédés de production de verre de sécurité. L’obtention d’une distribution de contraintes adéquate requiert un refroidissement intense et homogène à la fois, et ces deux propriétés sont difficiles à obtenir sur la courte durée de la trempe. Les batteries de jets utilisées dans la plupart des systèmes de trempe produisent un refroidissement adéquat mais souffrent d’inhomogénéité, à l’origine de défauts de trempe et de casse durant le processus.L’objectif de cette thèse est d’explorer des nouvelles configurations qui améliorent l’homogénéité du refroidissement en préservant son intensité. L’approche choisie consiste à implanter des jets rotatifs dans les réseaux de manière à accentuer le mélange des jets avant impact. Les études ont été menées principalement par simulation numérique, corroborées par des visualisations par enduit gras sur un banc d’essai dédié, conçu et réalisé dans le cadre de cette thèse.La première phase a été consacrée à la conception des générateurs de jets rotatifs et à l’étude de leur dynamique en mode isolé. Le développement d’une structure tourbillonnaire se formant à l’entrée de chaque lobe du dispositif de mise en rotation a été mis en évidence. L’interaction des jets rotatifs dans le réseau de refroidissement constitue la deuxième phase. Il apparait que la structure cellulaire du schéma d’impact n’est que marginalement perturbée par les jets rotatifs et que la présence de ces derniers n’influe que peu sur la dynamique de l’écoulement. Enfin, la modélisation détaillée des transferts de chaleur sur la plaque d’impact montre que les jets rotatifs ne contribuent que faiblement au refroidissement, mais que l’interférence avec le réseau de jets simples augmente légèrement le transfert de chaleur local au niveau de leur impact. Sans avoir obtenu les résultats escomptés, cette thèse a toutefois montré la complexité du système et le couplage fort entre les phases d’alimentation et d’évacuation de l’air de refroidissement. / Air quenching is widely applied in security glass manufacturing processes. Proper residual stresses distribution requires strong and homogeneous cooling and both are difficult to achieve over the very short time of the tempering process. Jet arrays used in most processes provide with sufficient cooling but suffer from inherent inhomogeneity, leading to quality loss of the glass product and, in extreme cases, to unacceptable breaking numbers during production.The objective of the present study is to investigate ways to improve cooling homogeneity while maintaining efficiency. For this purpose, swirling jets are located inside the jet arrays to enhance jet mixing prior to impingement. Numerical simulation is performed, corroborated by oil flow visualization and a dedicated test bench has been designed and set up within the frame of this thesis.The first part was concerned with the design of swirlers and their dynamic behaviour in standalone mode. It has been shown that a vortex is forming at the inlet of each swirl compartment. Inserting the swirlers within jet arrays constitutes the seconf phase. It turns out that the cellular structure of the impingement pattern is only marginally affected by the swirlers, which have a weak influence on the flow dynamics. Last, the detailed heat transfer modeling on the impingement surface shows that the swirlers themselves do barely contribute to the overall cooling, while the coupling with the simple jet array slightly improves the local heat transfer close to the impingement area. Although the expected outcome was not achieved, this thesis showed the flow complexity as well as the strong coupling between the feeding and the exhaust phases experienced by the cooling air.