the characterization of high aspect ratio rectangular jet flows

• DOI: 10.7939/r3-esk9-1e35
• Publication Date: 2020-01-01
• Authors: Carlos Mendez
• Keywords: Aspect Ratio; Jets; Turbulent Flow; Free Flow; Rectangular Flow

Steam assisted gravity drainage (SAGD) is an in-situprocess where an injection well and a production well are used to recover bitumen from oil sands that are past the point of viability for open mining techniques. During operation, sand control technologies are used on the wells to ensure the longevity of the SAGD system. Slotted liners are the most commonly used sand control technology for SAGD due to their low manufacturing costs and their superior mechanical integrity. The design of a slotted liner includes many narrow slots about the circumference. With the placement of the slotted liner on the injection well, the injected steam's flow field is rendered complex. To approach such a complex flow field, a fundamental understanding of the flow exiting a single slot is first necessary. This thesis aimed to investigate the flow field of a jet exiting a single slot. The aspect ratio, AR, and Reynolds number, Re, of the slot were chosen for study. In order to approach such a task, particle image velocimetry (PIV) techniques were applied to measure the flow field of the emerging jet. Streamwise and cross-sectional measurements were taken using two-dimensional (2D-PIV) and stereoscopic PIV (stereo-PIV) based setups, respectively. The single slot was made to have high-AR configurations of AR =100, 150, 200, and 210 at a constant area of Arec = 12 mm2, which resulted in an equivalent diameter of De= 3.91 mm. The flow rate of the jet exiting the slot was varied so that six Reynolds numbers were observed, at values of Re = 10800, 14400, 18000, 21600, 25200, and 28800. The streamwise measurements were taken within the X-Y plane, at Z = 0, and observed a downstream range spanning from X = 0 to X = 7De. In turn, the cross-sectional measurements were taken downstream from the slot exit, within the Y-Z plane at X = 3De, 5De, and 7De. The first study to be conducted was with regards to high-AR effects. When analyzing the streamwise measurements, many dissimilarities between low-AR and high-AR jets were observed when the velocity decay, streamwise turbulence intensity, and lateral velocity half-width were considered. Further dissimilarities were observed in the cross-sectional measurements when velocities, turbulence intensities, shear stresses, turbulent kinetic energy, and streamwise vorticity were considered. Each jet was found to display a high number of vortex pairs, so it was concluded that AR has a significant influence on the formation of the streamwise vorticity. It was also observed that small-scale disturbances at the slot exit led to large asymmetries in the distribution of vortex pairs, which in turn led to the jets displaying notable asymmetry. From these two observations on the vortex pairs, it was concluded that the initial distribution of the streamwise vorticity led to the overall differences that were perceived between low-AR and high-AR jets. Thus, it was concluded that a significant change in the downstream flow field occurs when high-AR configurations are utilized. The second study to be conducted was concerned with the influence of Re. Clear Re-based trends were observed to exist when the velocity decay, streamwise turbulence intensity, lateral velocity half-width, and cross-sectional streamwise velocity were considered. Based on the observations, it was observed that fully turbulent flow had not been reached for the first four Re configurations. Few differences were observed between the results of Re = 25200, and 28800, so it was concluded that the critical Reynolds number, Recritical, at which flow are fully turbulent had been passed. Thus, Recritical was observed to occur within the interval of Re = 21600 and 25200. This range was found to be slightly higher than the Recritical range given within the literature. It was further observed that Re directly influences the formation, distribution, and evolution of streamwise vortices. It was found that the number of streamwise vortex pairs and the dissipation of the vortex pairs downstream both increase with increasing Re. An array of evenly spaced vortex pairs was found to exist for fully turbulent jets. Though it was not concluded, it was proposed that the formation of such an array is what allows for fully turbulent jets to behave similarly.