Influence of innovative hydrogen multi strut injector with different spacing on cavity-based scramjet combustor

In this study, the flow dynamics with finite volume approach on commercial software Ansys-Fluent 20.0 to solve the compressible two-dimensional fluid flow with Reynolds Average Navier Stokes equation (RANS) equation by considering the density-based solver with Shaer stress transport model (SST) k- ω turbulent model. The species transport model with volumetric reaction and finite rate/eddy dissipation turbulence chemistry interaction is adopted to study the combustion phenomena. Additionally, the effect of spacing between the struts on the flow characters and performance of the combustor is studied by increasing the spacing of struts from 1 mm to 4 mm for each increment of 1 mm. It is found that the multi strut improves the mixing and combustion efficiency compared with that of the single strut owing to the formation of a significant separation layer, resulting in multiple shocks, vortices, and a larger recirculation zone. However, when the spacing of struts is increased further, the performance of the combustor is found to be deteriorating owing to the formation of larger separation layers. The recirculation zone is significant when the strut spacing is minimal and shrinks and restricts itself within the cavity when spacing is increased. So, for better performance of combustor, multi strut with minimum spacing is preferable.

Three-Dimensional Simulations of Scour around Pipelines of Finite Lengths

In the past few decades, there have been many numerical studies on the scour around offshore pipelines, most of which concern two-dimensional setups, with the pipeline infinitely long and the flow perpendicular to the pipeline. Based on the Ansys FLUENT flow solver, this study establishes a numerical tool to study the three-dimensional scour around pipelines of finite lengths. The user-defined functions are written to calculate the sediment transport rate, update the bed elevation, and adapt the computational mesh to the new boundary. The correctness of the model has been verified against the measurements of the conventional two-dimensional scour around a long pipe and the three-dimensional scour around a sphere. A series of computations are subsequently carried out to discover how the scour hole is dependent on the pipeline length. It is found that the equilibrium scour depth increases with the pipeline length until the pipeline length exceeds four times the pipe diameter.

Revealing the compressive and flow properties of novel bone scaffold structure manufactured by selective laser sintering technique

Additive manufacturing is revolutionizing the field of medical sciences through its key application in the development of bone scaffolds. During scaffold fabrication, achieving a good level of porosity for enhanced mechanical strength is very challenging. The bone scaffolds should hold both the porosity and load withstanding capacity. In this research, a novel structure was designed with the aim of the evaluation of flexible porosity. A CAD model was generated for the novel structure using specific input parameters, whereas the porosity was controlled by varying the input parameters. Poly Amide (PA 2200) material was used for the fabrication of bone scaffolds, which is a biocompatible material. To fabricate a novel structure for bone scaffolds, a Selective Laser Sintering machine (SLS) was used. The displacement under compression loads was observed using a Universal Testing Machine (UTM). In addition to this, numerical analysis of the components was also carried out. The compressive stiffness found through the analysis enables the verification of the load withstanding capacity of the specific bone scaffold model. The experimental porosity was compared with the theoretical porosity and showed almost 29% to 30% reductions when compared to the theoretical porosity. Structural analysis was carried out using ANSYS by changing the geometry. Computational Fluid Dynamics (CFD) analysis was carried out using ANSYS FLUENT to estimate the blood pressure and Wall Shear Stress (WSS). From the CFD analysis, maximum pressure of 1.799 Pa was observed. Though the porosity was less than 50%, there was not much variation of WSS. The achievement from this study endorses the great potential of the proposed models which can successfully be adapted for the required bone implant applications.

Specific Features of Flow on Compression Surfaces of a Convergent Air Intake

The results of computational and experimental studies of a model of a hypersonic convergent air intake are presented. Experimental studies were carried out in a hot-shot wind tunnel IT-302M SB RAS at a Mach number M = 5.7 and an angle of attack α = 4 °. Numerical modeling was carried out in a three-dimensional setting in the ANSYS Fluent software package. The calculations were carried out in 4 versions using different turbulence models: k-ɛ standard, RNG k-ɛ, k-ɷ standard and k-ɷ SST. The features of the flow structure are established. The pressure distributions on the compression surfaces and in the air intake channel are obtained. The separated flow at the entrance of the inner channel was studied. It was found that the use of various turbulence models has a significant effect on the size and position of separation. The best agreement between the calculated and experimental data on the level of static pressure was shown by the variant with the k-ɛ standard turbulence model.

Conjugate Free Convection Heat Transfer and Thermodynamic Analysis of Infrared Suppression Device with Cylindrical Funnels

A convection system can be designed as an energy-efficient one by making a considerable reduction in exergy losses. In this context, entropy generation analysis is performed on the infrared suppression system numerically. In addition, results due to heat transfer are also shown. The numerical solution of the Navier-stokes equation, energy equation, and turbulence equation is executed using ANSYS Fluent 15.0. To perform the numerical analysis, different parameters such as the number of funnels, Rayleigh number (Ra), inner surface temperature, and geometric ratio are varied in the practical range. Results are shown in terms of heat transfer, entropy generation, irreversibility (due to heat transfer and fluid friction), and Bejan number with some relevant parameters. Streamlines and temperature contours are also provided for better visualization of temperature and flow field around the device. Results show that heat transfer and mass flow rate increase with the increase in Ra. Entropy generation and the irreversibility rise with an increase in the number of funnels and geometric ratio. Also, the Bejan number decreases with an increase in Ra and the number of funnels. A cooling time is also obtained using the lumped capacitance method.

Impact of Thermal Dissipation on the Lighting Performance and Useful Life of LED Luminaires Applied to Urban Lighting: A Case Study

Currently, LED technology is an established form of lighting in our cities and homes. Its lighting performance, durability, energy efficiency and light, together with the economic savings that its use implies, are displacing other classic forms of lighting. However, some problems associated with the durability of the equipment related to the problems of thermal dissipation and high temperature have begun to be detected, which end up affecting their luminous intensity and the useful life. There are many studies that show a direct relationship between the low quality of LED lighting and the aging of the equipment or its overheating, observing the depreciation of the intensity of the light and the visual chromaticity performance that can affect the health of users by altering circadian rhythms. On the other hand, the shortened useful life of the luminaires due to thermal stress has a direct impact on the LCA (Life Cycle Analysis) and its environmental impact, which indirectly affects human health. The purpose of this article is to compare the results previously obtained, at different contour temperatures, by theoretical thermal simulation of the 3D model of LED street lighting luminaires through the ANSYS Fluent simulation software. Contrasting these results with the practical results obtained with a thermal imaging camera, the study shows how the phenomenon of thermal dissipation plays a fundamental role in the lighting performance of LED technology. The parameter studied in this work is junction temperature (Tj), and how it can be used to predict the luminous properties in the design phase of luminaires in order to increase their useful life.

APPLICATION OF THE VOLUME OF FLUID METHOD TO SIMULATE THE PROCESS OF MELTING AND MOVEMENT OF FUEL

The article considers the possibility of using the method of multiphase fluid Volume of Fluid (VOF), the Ansys Fluent program, for numerical simulation of the melting process of the materials of the experimental device and their movement over the volume of the computational domain. For modeling the design of a typical experimental device tested in the reactor was selected, a two-dimensional computational model was developed, methods for solving the thermal problem were described, and the simulation results were presented.

Automatic Blade Shape Optimization of a Three-Bladed Modified Savonius Turbine

In this study, the performance of a new wind turbine design derived from a conventional Savonius turbine is optimized by numerical simulation. The new design consists of three blades without passage between them (closed center). The coupling between the CFD codes (ANSYS Fluent) and the optimizer (OPAL) is used through an automatic procedure in-house codes, as documented, for example, in Thévenin et al.’s Optimization and Computational Fluid Dynamics (2008). A single-objective function (output power coefficient, Cp) is considered as the target of the optimization technique and the shape of the blade as an optimization parameter and relies on evolutionary algorithms. An optimal solution can emerge from this optimization study. By comparison between regular design (semi-cylindrical shape blades) and the optimal configuration, a considerable improvement (up to 7.13% at λ = 0.7) of the optimal configuration performance can be obtained in this manner.

3D AND 1D SIMULATIONS OF DIESEL PARTICULATE FILTER (DPF)

DPF is an important device in the exhaust system of Diesel engine. In this paper we simulate velocity and pressure distributions in DPF to determine kinematic and hydraulic characteristics. This will provide the basis for designing and selecting size of channels in DPF. Numerical simulations were made using ANSYS Fluent commercial software and OpenFOAM open-source software. The results show that the difference between the two softwares is negligible. A compact 1D mathematical model developed based on the Darcy equation, momentum equation and continuity equation. The mathematical model solved by shooting method for boundary value problem. Simulation results from 1D and 3D approaches are very coincident.