mixing characteristics of Jet emerging from a subsonic nozzle exit has been experimented and the results are compared with uncontrolled Jet and controlled Jet configurations. The mixing enhancement was achieved using a passive method of Jet control in which tandem tabs arrangement with rectangular cross section are fixed at the nozzle exit. Two Tab configurations, the Tandem tab (TT) and Stepped Tandem Tab (STT) are used to enhance the mixing characteristics of the Jet, the aspect ratio (length /width) of the tabs was 1.67 offering a blockage ratio of 9.55% to the nozzle exit. The blockage ratio of TT and STT configurations are maintained to be equal so that the mixing characteristics can be compared. The axial and radial Jet spread are compared for nozzle exit Mach numbers of 0.6, 0.8 and 1.0. The TT controlled Jet offered a potential core reduction of 63%, 78% and 82% for Mach numbers 0.6, 0.8 and 1.0 respectively. The STT controlled Jet offered a potential core reduction of 89%, 90% and 85% for Mach numbers 0.6, 0.8 and 1.0 respectively. The radial spread of uncontrolled Jet, controlled Jet with TT and STT are plotted at several X/D locations and found that the controlled Jets have more Jet spread in both radial directions. A simulation is conducted for Jets with exit Mach number 0.8 and the results are validated with the experimental findings. Based on the preliminary experimentation and computation, the STT controlled Jet achieved better Jet mixing through more potential core reduction and radial spread characteristics as compared to the TT configuration and base nozzle.

mixing is an important unit operation in many chemical engineering applications. Nowadays, the Jet mixing is widely used and going to be replaced with conventional mixers as a result of its simplicity, high performance and low costs. Jet mixing in tanks has been investigated by many researchers. However, no comprehensive literature review exists. In the present review detailed investigation of previous studies which are categorized into two general classes: experimental and simulation based on CFD techniques were stressed. The influence of geometrical and operational parameters is discussed and a general explanation about existing information was presented. In spite of some differences in data from various sources, general conclusions and guidelines for optimum design selection were obtained

The purpose of this study is to numerically analyze the effect of vortex generators that are shaped like vanes in enhancing the mixing of subsonic and sonic Jet and to determine the best design which yields maximum reduction in Jet potential core length and minimum thrust loss at the nozzle exit. Four different nozzle designs namely, models A, B, C and D are designed and compared with a base nozzle which is a plain circular nozzle without any vanes. The simulation is performed in ANSYS Fluent using the S-A turbulence model. The centerline pressure decay and radial pressure decay from models A to D are compared with that of the base nozzle to determine the ability of the vane to enhance the Jet mixing characteristics. To evaluate the thrust loss, the total pressure at the exit plane of models A to D is measured and compared with that of the base nozzle. When comparing all the designs, it is observed that Model B produces the highest reduction in potential core length which is 66. 4% at Mach no. 1 and Model D produces minimum total pressure loss which is 0. 47% at Mach no. 0. 4. In contrast to the conventional method, this design introduces a novel approach by placing the vanes parallel to the flow instead of the usual perpendicular arrangement. This unique configuration allows the vanes to redirect the flow rather than hinder it, resulting in a total pressure loss of less than 3%.

In this research, the positive mixing length and trajectory characteristics of a buoyant Jet was investigated. Jet flux is dependent on parameters such as initial velocity, port diameter, concentration of Jet and flow conditions in the receiving fluid. A buoyant Jet fluid governing equation with relevant logical assumptions was used to drive the required dimensionless functions using dimensional analysis. A physical model was built to evaluate the function of these parameters. Testing was done at varying velocities, concentrations and initial port diameters. The length of the falling Jet trajectory was analyzed as the ratio of trajectory length to port diameter versus relative trajectory elevation. The results showed that increasing Jet diameter and Jet momentum had a significant effect on Jet trajectory. Increasing Jet fluid density caused a density gradient between the Jet and receiving fluid and a change in the buoyancy forces involved which had a major influence on the length of the falling Jet trajectory. Hence at a given density, increasing the diameter from 5-8 mm or 8-15 mm decreased the densimetric Froude number 30-40% for different velocities and the ratio of the length of positive flux buoyancy to port diameter decreased 20-35%. Findings showed that doubling the increase in density decreased the length of positive flux buoyancy 5-20%.

The effect of Jet positions on the homogenization progress of a dye in a rectangular tank equipped with a Jet was studied. Water entered the tank laterally from the top and left the tank from the opposite wall at the same height. The suction position was fixed at one of the tank corners and seven positions were considered for the Jet nozzle. A predefined volume of the dark Nigrosine was injected to the tank input as the tracer during 4s in all experiments. During the dye injection and mixing progress, the front and bottom views of the tank were recorded by a digital camera. The experimental results showed that as the Jet nozzle was installed in the opposite wall from the tank input, the worst performance was obtained in comparison with the other Jet positions. However, the Jet nozzle position of 90° with respect to the tank input had the best performance. All of the experiments were modeled by Computational Fluid Dynamics (CFD). Finally, the CFD predicted dye spreading was verified by the experimental observations and a good agreement was observed between the CFD and experimental results.

This present investigation inspects the mixing promoting the efficacy of two short delta tabs which is axis-symmetric, mounted circumferentially antipodal at the end for a Mach number 1. 8 convergent-divergent circular nozzle computationally with the nozzle pressure ratios (NPRs) ranging from 4 to 8 with a unit step of one that covers all the critical states of the Jet i. e., the overexpanded, the correctly-expanded and the underexpanded states of the Jet. In order to minimize thrust loss, the geometric blockage offered by each delta tab is kept within 2. 5%. The computational assessment is conducted by adopting and employing ANSYS-FLUENT which is a comprehensive engineering simulation software. Further, the entire steady flow computations are carried out on a three-dimensional numerical enclosure by implementing Reynolds-averaged Navier-Stokes equations along with the κ-omega shear stress transport turbulence model. Interestingly, vital plots including the centerline pressure decay as well as the pressure profiles are depicted for uncontrolled and controlled Jets accordingly. Also, numerically obtained schlieren illustrations are adopted for visualization of the shock cell structure, expansion fan, and the Mach wave structure existing in the stream field. Furthermore, Mach variations are also depicted for the varied nozzle pressure ratios in the form of contours. The shock-strength, shock-length, and the progressive disparity found in the shock structures are reasonably demonstrated by the Mach contours. The results of this research are discovered to be in sensible concurrence with the earlier established exploratory results. A maximum core length reduction of 70. 81% is observed in underexpanded condition at the nozzle pressure ratio of 6. Absorbingly, a controlled Jet has been seen to get split in equal proportion along the succeeding direction of the nozzle exit at a distance of approximately 5De, De indicating the exit diameter of the nozzle. Moreover, it was appealing to detect the development of Jet dispersion along the succeeding direction of the nozzle exit periphery. The short delta tabs also performed satisfactorily in diminishing the waves and reducing the shock cell length as depicted via numerical schlieren images.

In the current research, numerical analysis was used to investigate the flow behavior through the axial Jet-pump with various mixing chamber configurations (straight pipe and straight pipe-diffuser-straight pipe) in the presence of inlet swirling flow and its influence on the pump performance. The effects of introducing inlet swirling flow in the suction chamber and in the motive flow line, are numerically investigated. The optimum swirl angle in the suction chamber is found to be 45o which yields the maximum pump efficiency of 38.08 % for the second configuration of mixing chamber system. Consequently, the inlet swirl generally decreases the desired mixing chamber length. Additionally, the new mixing chamber configuration enhances the mixing process compared with the traditional mixing chamber. On the other hand, imparting a swirl in the motive line inversely affected the pump performance. Engendering a swirl in suction chamber causes an improvement by 12.76 % in the pump efficiency compared to the same pump configuration without swirl. The optimum tail pipe diffuser angle is found to be 3o.