CFD analysis of jet flows ejected from different nozzles (original) (raw)
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CFD Investigation for different nozzle jets
Materials Today: Proceedings, 2017
Nozzle delivers thrust and gives momentum to the aerospace vehicle. Nozzle design is to be developed with respect to the application based on various factors under consideration during evolving of a system design. Specific impulse required is one of the major factors to define nozzle configuration with minimum variation in thrust delivered. As supersonic jet flow leaves the nozzle, it becomes a free shear layer, and action of turbulence dominates flow developments farther downstream. Therefore jet flow contains large interactions with surrounding medium. These combinations include turbulent mixing and compressibility effects such as isentropic expansion and shock. Numerical simulations are performed using commercially available software FLUENT to investigate and understand the performance of conical and scarfed nozzle. CFD Studies carried out for selecting a suitable mesh and selection of suitable turbulence model for computing nozzle jet flow field. Simulations were made using Spalart-Allmaras model and SST model. Based on the results, scarfed nozzle gives relatively low mach number compared to conical nozzle. The scarfed nozzle is preferred due to the missile configuration constraints.
Evaluation of turbulence models for the air flow in a planar nozzle
In gas flows at supersonic speeds, shock waves, flow separation and turbulence are produced due to sudden changes in pressure. The behavior of the compressible flow can be studied by using experimental equipment or by numerical methods with codes of the computational fluid dynamics (CFD). In the present work, the air flow is simulated in a 2D computational domain with the ANSYS-Fluent code version 12.1 for the geometry of a planar nozzle, using the Reynolds averaged Navier-Stokes (RANS) equation, with the objective of evaluating five turbulence models: SST k − ω, k − e standard, k − ω standard, k − kl − ω of transition and RSM. Numerical results of static pressure profiles were obtained for the walls of the nozzle and of the shock wave forms in the flow field, for two conditions of pressure ratios rp = 2.008 and rp = 3.413, which were compared with the experimental data of Hunter's work. It is concluded that the numerical results obtained with the turbulence model SST k − ω of Menter (1994) are more adjusted to the experimental data of static pressure and shock wave forms.
Influence of Nozzle Configuration on the flow field of Multiple Jets
2017
Turbulent jet flows with multiple nozzle inlets are investigated computationally using OpenFOAM. The configurations vary from single to five axisymmetric nozzles. First order closure is used with Reynolds Averaged Navier-Stokes equations. Computed results are compared with the available experimental data. The effect of nozzle configuration on the jet flow field is discussed with predicted mean flow and turbulent flow data. Near field of multiple jets shows non-linear behavior. Multiple jets show better performance in the near field based on entrainment, secondary flows and area averaged turbulent kinetic energy. The downstream evolution of multiple jets differs for configurations with and without central jet. The shape parameter confirms the evolution of multiple jets towards an axisymmetric jet.
CFD Analysis of C-D Nozzle compared with Theoretical & Experimental Data
2017
In modern Computational Fluid Dynamic (CFD) Analysis of Convergent-Divergent (C-D) Nozzles, current research has shown that, it is common practice to use either experimental or analytical results to predict the accuracy of the CFD models by comparison of the results. It is also commonly agreed, amongst the literature reviewed, that the CFD modelling software packages available do not accurately model turbulence for applications such as transonic C-D nozzles. This study aims to develop a theoretical approach for calculation of flow properties along the axis of the C-D nozzle based on the fundamental gas dynamic equations. The theoretical analyses is validated by experimental data. Then, the CFD model is used to simulate the experimental cases which are compared with the data from both theoretical analysis and experimental measurements. Then, the validated CFD model can be used for more complex analyses, representing more elaborate flow phenomena such as internal shockwaves and boundary layers. The geometry used in the analytical study and CFD simulations constructed to model the experimental rig. The [1, 2] analytical study is undertaken using isentropic and adiabatic relationships and the output of the analytical study, the 'shockwave location tool', is created. The results from the analytical study are then used to optimise the redesign an experimental rig to for more favorable placement of pressure taps and gain a much better representation of the shockwaves occurring in the divergent section of the nozzle. The results from the CFD model can then be directly compared other results in order to gauge the accuracy of each method of analysis. The validated model can then be used in order to create several, novel nozzle designs which may offer better performance and ease of manufacture and may present feasible improvements to existing high-speed flow applications.
Computational Fluid Dynamics (CFD) is a branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. Computers are required to simulate the interaction of liquids and gases with surfaces defined by boundary conditions. In this paper, CFD analysis of pressure, velocity (mach number) and temperature of flow for a Convergent-Divergent nozzle of two different diverged angles (50 & 100) has been performed, because the fluid properties like pressure, velocity, and temperature are dependent on the cross section of the nozzle which affects the flow within the nozzle. A nozzle is a device designed to control the direct ion or characteristics of a fluid flow as it exits or enters. The analysis has been performed according to the diverged angle of the C-D nozzle and keeping the same input conditions. Our objective is to investigate theoretically what we have studied about sonic (M=1), sub-sonic (M<1) and supersonic (M>1) and flow parameters, we are proving that by CFD simulation. Initially the 2-D model of the C-D nozzles is taken in the present research work. The analysis type is 2-D PLANER. The modeling of the C-D nozzles has been done and later on mesh generation and analysis have been carried out in Ansys-Fluent 14.0 and various contours, plots and vectors of pressure, velocity and temperature have been taken and their variation according to different divergent angle nozzles has been studied.
A numerical Investigation of the Flow in Water Jet Nozules
Journal of Thermal Engineering, 2016
In this study, flow inside the nozzles are investigated by means of finite volume method. Firstly, some analyses are carried out in 2-D in order to compare and validate the results with the experimental ones. Later, 3-D models are created to have different nozzle geometries. 3-D analyses are made and outlet mass flow rates, velocities and reaction forces are calculated in the same inlet pressure level for different nozzle geometries. Two equation k-ω turbulence model is chosen as the turbulence model. At the end of this numerical study, the nozzle geometry with minimum reaction force and maximum mass flow rate is determined thanks to computational fluid dynamics (CFD) based on finite volume method (FVM).
International Journal of Applied Engineering Research
One of the significant properties of fluids in motion is that they adjust to succumb to their environments. The various dynamic physics are merely the outcome of these adjustments. Nozzles transform pressure energy of fluids into kinetic energy using their peculiar geometry. Numerous studies on nozzle profiles have proven to be fruitful in light of their contributions in the field of aerospace, fluid transport and many other applications. Here we investigate the dynamic characteristics of a jet emerging from a lobed nozzle with sharp ended corrugations numerically by utilising tools of computational fluid dynamics. For validation purposes, the numerical investigation has been compared to numerical study by Kriparaj et al. (2018) and experimental findings by Anderson et al. (2005). The results suggest that velocity decay associated with multilobed nozzles with pointed corrugations are higher than conventional nozzles and smoothly corrugated designs. The centerline velocity appears to increase downstream as expected, but the radial velocity profiles at corresponding axial sites reported by Kriparaj et al. (2018) appear to have shifted to locus points that lie between characteristic profiles of conventional circular nozzles and smooth corrugated lobed geometry.
CFD Study of Effects of Geometry Variations on Flow in a Nozzle
Engineering Applications of Computational Fluid Mechanics, 2012
Reynolds-Averaged Navier-Stokes simulations have been performed to investigate the effect of nozzle geometry on the turbulence characteristics of incompressible fluid flow through nozzles at Reynolds number of approximately 50,000. Four nozzles have been considered: a baseline nozzle and three modified nozzles (extended, grooved and ringed). The flow in these nozzles has been simulated using different turbulence closure models, including Spalart-Allmaras, variants of k-ε and k-ω, and the Reynolds Stress Model (RSM). By comparison to experimental data, it is shown that the RSM produces more accurate results for the prediction of turbulent fluctuations. The presence of a ring significantly increases both the turbulence intensity and mean velocity at the exit, and requires a much higher inlet pressure to move the fluid through the nozzle. On the other hand, cutting a groove near the exit or extending the nozzle has little effect on the exit flow characteristics.
International Journal of Engineering & Technology, 2018
A numerical simulation was carried out to compare various turbulence models simulating axisymmetric nozzle flow past suddenly expanded ducts. The simulations were done for L/D = 10. The convergent-divergent nozzle has been modeled and simulated using the turbulence models: The Standard k-ε model, The Standard k-ω model and The SST k-ω model. Numerical simulations were done for Mach numbers 1.87, 2.2, and 2.58 and the nozzles were operated for NPRs in the range from 3 to 11. From the numerical analysis it is apparent that for a given Mach number and effect of NPR will result in maximum gain or loss of pressure. Numerical results are in good agreement with the experimental results.