Experimental and Numerical Investigation of a Miniature Additively Manufactured Vortex Tube

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
Gregory Wallace ◽  
Carl Bunge ◽  
Jacob Leachman ◽  
Konstantin I. Matveev
Keyword(s):  
Additive Manufacturing ◽  
Vortex Tube ◽  
Complex Geometry ◽  
Pressure Ratio ◽  
Navier Stokes ◽  
Cooling Power ◽  
Variable Diameter ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Vortex Tubes

Abstract Ranque–Hilsch vortex tubes are simple devices that can produce a cooling effect using compressed air. A key advantage of vortex tubes is the lack of moving solid parts; however, their efficiencies are relatively low. The present study focuses on the development of a miniature variable-diameter tube using additive manufacturing. A metal-based 3D printing technique was utilized to fabricate this vortex tube monolithically. Computational fluid dynamics simulations employing software star-ccm+ with a compressible Reynolds-Averaged Navier–Stokes (RANS) approach and the elliptic-blending lag k-epsilon turbulence model have been applied to model thermofluid processes inside the vortex tube, to good agreement with the experiment. A temperature decrease of 13.3 °C and a cooling power of approximately 4 W were experimentally achieved with a pressure ratio of 4 in the air at normal conditions. This result shows promise for the goal of utilizing additive manufacturing to design and build complex-geometry vortex tubes intended for use with cryogenic fluids.

scholarly journals Evaluation of Active Heat Sinks Design under Forced Convection—Effect of Geometric and Boundary Parameters

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2041
Author(s):  
Eva C. Silva ◽  
Álvaro M. Sampaio ◽  
António J. Pontes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Trapezoidal Shape ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This study shows the performance of heat sinks (HS) with different designs under forced convection, varying geometric and boundary parameters, via computational fluid dynamics simulations. Initially, a complete and detailed analysis of the thermal performance of various conventional HS designs was taken. Afterwards, HS designs were modified following some additive manufacturing approaches. The HS performance was compared by measuring their temperatures and pressure drop after 15 s. Smaller diameters/thicknesses and larger fins/pins spacing provided better results. For fins HS, the use of radial fins, with an inverted trapezoidal shape and with larger holes was advantageous. Regarding pins HS, the best option contemplated circular pins in combination with frontal holes in their structure. Additionally, lattice HS, only possible to be produced by additive manufacturing, was also studied. Lower temperatures were obtained with a hexagon unit cell. Lastly, a comparison between the best HS in each category showed a lower thermal resistance for lattice HS. Despite the increase of at least 38% in pressure drop, a consequence of its frontal area, the temperature was 26% and 56% lower when compared to conventional pins and fins HS, respectively, and 9% and 28% lower when compared to the best pins and best fins of this study.

Numerical Simulation using RANS-based Tools for America’s Cup Design

2003 ◽  
Author(s):  
Geoff Cowles ◽  
Nicola Parolini ◽  
Mark L. Sawley
Keyword(s):  
Design Process ◽  
Water Surface ◽  
Navier Stokes ◽  
Computational Fluid Dynamics Simulations ◽  
America’S Cup ◽  
Dynamics Simulations ◽  
École Polytechnique ◽  
Cup Design ◽  
Cup Drawing

The application of Computational Fluid Dynamics simulations based on the Reynolds Averaged Navier- Stokes (RANS) equations to the design of sailing yachts is becoming more commonplace, particularly for the America's Cup. Drawing on the experience of the Ecole Polytechnique Fédérale de Lausanne as Official Scientific Advisor to the Alinghi Challenge for the America’s Cup 2003, the role of RANS-based codes in the yacht design process is discussed. The strategy for simulating the hydrodynamic flow around the boat appendages is presented. Two different numerical methods for the simulation of wave generation on the water surface are compared. In addition, the aerodynamic flow around different sail configurations is investigated. The benefits to the design process as well as its limitations are discussed. Practical matters, such as manpower and computational requirements, are also considered.

scholarly journals Numerical investigation of a small water turbine used for the power supply of underwater vehicles

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878365 ◽  
Author(s):  
Zhaoyong Mao ◽  
Jingang Bai
Keyword(s):  
Stokes Equations ◽  
Underwater Vehicles ◽  
Geometric Parameters ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Sliding Mesh ◽  
Small Water ◽  
Water Turbine ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

The development of underwater vehicles is facing the problem of sustainable energy supply. This study introduces a small water turbine, the Lenz turbine, for energy generation from the ocean currents which will provide energy for the underwater vehicles. Computational fluid dynamics simulations of the effect of geometric parameters, including the blade radius, chord length, and pitch angle, on the performance of the turbine are conducted. The Reynolds-Averaged Navier–Stokes equations are numerically solved with a sliding mesh method. Thirteen sets of tests in total are performed at different values of tip-speed ratios. The tests are divided into three groups to study the effect of the three parameters mentioned above, separately. The obtained power coefficients, coefficient of torque, and the dynamic torque on a blade are then compared in each group of tests. Pressure contours and velocity contours are given to explain the reason how the geometric parameters affect the rotor performance.

scholarly journals A Comparison of Experimental and Computational Heat Transfer Results for a Leading Edge Impingement System

2018 ◽  
Vol 3 (4) ◽  
pp. 23
Author(s):  
Robert Pearce ◽  
Peter Ireland ◽  
Ed Dane ◽  
Janendra Telisinghe
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Turbine Blades ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
High Heat ◽  
Navier Stokes ◽  
Spatially Resolved ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Leading edge impingement systems are increasingly being used for high pressure turbine blades in gas turbine engines, in regions where very high heat loads are encountered. The flow structure in such systems can be very complex and high resolution experimental data is required for engine-realistic systems to enable code validation and optimal design. This paper presents spatially resolved heat transfer distributions for an engine-realistic impingement system for multiple different hole geometries, with jet Reynolds numbers in the range of 13,000–22,000. Following this, Reynolds-averaged Navier-Stokes computational fluid dynamics simulations are compared to the experimental data. The experimental results show variation in heat transfer distributions for different geometries, however average levels are primarily dependent on jet Reynolds number. The computational simulations match the shape of the distributions well however with a consistent over-prediction of around 10% in heat transfer levels.

scholarly journals Aerodynamic optimisation of the rear wheel fairing of the land speed record vehicle BLOODHOUND SSC

2016 ◽  
Vol 120 (1228) ◽  
pp. 930-955
Author(s):  
J. Townsend ◽  
B. Evans ◽  
T. Tudor
Keyword(s):  
Design Space ◽  
Aerodynamic Drag ◽  
Ground Plane ◽  
Rear Wheel ◽  
Navier Stokes ◽  
High Dimensional ◽  
Aerodynamic Properties ◽  
Function Design ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

ABSTRACTThis paper describes the design optimisation study used to aerodynamically optimise the fairings that cover the rear wheels of the Land Speed Record vehicle, BLOODHOUND SuperSonic Car (SSC). Initially, using a Design of Experiments approach, a series of Computational Fluid Dynamics simulations were performed on a set of parametric geometries, with the goal of identifying a fairing geometry that was aerodynamically optimised for the target speed of 1,000 mph. Several aerodynamic properties were considered when deciding what design objectives the fairings would be optimised to achieve; chief amongst these was the minimisation of aerodynamic drag. A parallel, finite-volume Navier–Stokes solver was used on unstructured meshes in order to simulate the complex aerodynamic behaviour of the flow around the vehicle’s rear wheel structure, which involved a rotating wheel, and shockwaves generated close to a supersonic rolling ground plane. It was found that the simple response surface fitting approach did not sufficiently capture the complexities of the optimisation objective function across the high-dimensional design space. As a result, a Nelder–Mead optimisation approach was implemented, coupled with Radial Basis Function design space interpolation to find the final optimised fairing design. This paper presents the results of the optimisation study as well as indicating the likely impact this optimisation will have on the ultimate top speed of this unique vehicle.

Eulerian and Lagrangian scaling properties of randomly advected vortex tubes

1996 ◽  
Vol 326 ◽  
pp. 417-436 ◽  
Author(s):  
N. A. Malik ◽  
J. C. Vassilicos
Keyword(s):  
Frequency Spectrum ◽  
Differential Rotation ◽  
Vortex Tube ◽  
Analytical Calculation ◽  
Navier Stokes ◽  
Spectral Broadening ◽  
Scaling Properties ◽  
Spiral Vortex ◽  
Burgers Vortex ◽  
Vortex Tubes

We investigate the Eulerian and Lagrangian spectral scaling properties of vortex tubes, and the consistency of these properties with Tennekes’ (1975) statistical advection analysis and universal equilibrium arguments. We consider three different vortex tubes with power-law wavenumber spectra: a Burgers vortex tube, an inviscid Lundgren single spiral vortex sheet, and a vortex tube solution of the Euler equation. While the Burgers vortex is a steady solution of the Navier–Stokes equation, the other two are unsteady solutions of, respectively, the Navier–Stokes and the Euler equations. In our numerical experiments we study the vortex tubes by subjecting each of them to external ‘large-scale’ sinusoidal advection of characteristic frequency f and length scale ρ.Not only do we find that the Eulerian frequency spectrum ϕE(ω) can be derived from the wavenumber spectrum E(k) using the simple Tennekes advection relation ω ∼ k for all finite advection frequencies f when the vortex is steady, but also when the vortex is unsteady, and in the Lundgren case even when f = 0 owing to the self-advection of the Lundgren vortex by its own differential rotation.An analytical calculation using the method of stationary phases for f = 0 shows that for large enough Reynolds numbers the combination of strain with differential rotation implies that ϕL(ω) ∼ ω−2+Const for large values of ω. We verify numerically that ϕL(ω) does not change when f ≠ 0. With the Burgers vortex tube we are in a position to investigate the spectral broadening of the Eulerian frequency spectrum with respect to the Lagrangian frequency spectrum. A spectral broadening does exist but is different from the spectral broadening predicted by Tennekes (1975).

scholarly journals The improvement of the methodology for the calculation of the vortex tubes for gas conditioning

2018 ◽  
pp. 53-61
Author(s):  
O. R. Kondrat ◽  
A. D. Hutak
Keyword(s):  
Mathematical Model ◽  
Vortex Tube ◽  
Pressure Ratio ◽  
Thermodynamic Efficiency ◽  
Geometrical Parameters ◽  
Method Of Calculation ◽  
Heating Effects ◽  
Gas Conditioning ◽  
Ejection Event ◽  
Vortex Tubes

The process of temperature flow separation of gas in vortex tube is studied. The enhanced mathematical model of vortex tube has been proposed. With the help of various methods the conditions for the ejection event in vortex tube has been researched. The influence of several geometrical parameters on thermodynamic efficiency of vortex tube has been defined. Based on the proposed mathematical model, a new method of calculation the geometrical parameters (nozzle diameter, diaphragm diameter, sizes of conical valve) and the degree of flow, which are needed to obtain the requested cooling and heating effects depending on the available pressure ratio, has been developed.

Multi-Dimensional, Transient Fluid Flow Simulations in the Manifold of a Four-Stroke Single-Cylinder Engine

2005 ◽  
Author(s):  
T. N. C. Anand ◽  
R. V. Ravikrishna
Keyword(s):  
Complex Geometry ◽  
Film Formation ◽  
Intake Manifold ◽  
Two Phase ◽  
Single Cylinder ◽  
Engine Cylinder ◽  
Computational Fluid Dynamics Simulations ◽  
Recirculation Zones ◽  
Dynamics Simulations ◽  
Two Wheeler

Multi-dimensional computational fluid dynamics simulations were carried out on the intake manifold and cylinder of a four-stroke single cylinder two-wheeler engine. The complex geometry of the manifold and the engine cylinder, and the motion of the intake valve were taken into consideration. Both air flow and two-phase calculations were done to predict the trajectory of the liquid fuel and identify regions of impingement which could lead to film formation and high emissions at startup. The results show that the present geometry of the manifold is non-optimum as large recirculation zones are present. The two-phase simulations show that fuel transport is significantly affected due to the recirculation under idling conditions and significant impingement occurs. The numerical results obtained could be utilized to improve the flow in the manifold for lowering emissions.

NUMERICAL STUDY OF DETONATION PROPAGATION IN VISCOUS TURBULENT FLOW IN A DUCT

2020 ◽  
Author(s):  
V. A. SABELNIKOV ◽  
◽  
V. V. VLASENKO ◽  
S. BAKHNE ◽  
S. S. MOLEV ◽  
...  
Keyword(s):  
Complex Geometry ◽  
Numerical Study ◽  
Navier Stokes ◽  
Detonation Waves ◽  
Detonation Propagation ◽  
Eddy Simulation ◽  
Detonation Structure ◽  
Classical Studies ◽  
Large Eddy ◽  
Physical Effects

Gasdynamics of detonation waves was widely studied within last hundred years - analytically, experimentally, and numerically. The majority of classical studies of the XX century were concentrated on inviscid aspects of detonation structure and propagation. There was a widespread opinion that detonation is such a fast phenomenon that viscous e¨ects should have insigni¦cant in§uence on its propagation. When the era of calculations based on the Reynolds-averaged Navier- Stokes (RANS) and large eddy simulation approaches came into effect, researchers pounced on practical problems with complex geometry and with the interaction of many physical effects. There is only a limited number of works studying the in§uence of viscosity on detonation propagation in supersonic §ows in ducts (i. e., in the presence of boundary layers).

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