Numerical and Experimental Study of Cooling Fan Noise

2014 ◽  
Vol 592-594 ◽  
pp. 1930-1934
Author(s):  
G.V.R. Seshagiri Rao ◽  
V.V. Subbarao ◽  
C. Prabakara Rao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Experimental Studies ◽  
Axial Flow ◽  
Field Analysis ◽  
Navier Stokes ◽  
Axial Flow Fan ◽  
Navier Stokes Equation ◽  
Volume Method ◽  
Physical Features

Abstract. This paper presents the results of experimental studies of the noise of marine application pump axial flow fan. Axial flow fan is verified by both geometrical and experimental approaches. This section includes grid system used in geometric simulation, and boundary conditions. In order to know the complicate and complex physical features of an axial flow fan, a commercial computational fluid dynamics code, FLUENT, is utilized to perform the flow field analysis, which solves the Navier–Stokes equation using an amorphous finite volume-method. As a commercial computational fluid dynamics code, FLUENT has been extensively used in many turbo machinery applications. In this paper the noise predicted according to geometrical results will be compare with investigational results.

scholarly journals Mixing Performance of Counter-Axial Flow Impeller using Computational Fluid Dynamics

2018 ◽  
Vol 8 (02) ◽  
Author(s):  
Ian Torotwa ◽  
Changying Ji
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Axial Flow ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Rushton Turbine ◽  
Mixing Performance ◽  
Computational Fluid Dynamics Cfd

In this study, turbulent flow fields in a baffled vessel stirred by counter-axial flow impeller have been investigated in comparison to the Rushton turbine. The resultant turbulence was numerically predicted using computational fluid dynamics (CFD). Turbulence models were developed in ANSYS Fluent 18.1 solver using the Navier-Stokes equation with the standard k-ε turbulence model. The Multiple Reference Frame (MRF) approach was used to simulate the impeller action in the vertical and horizontal planes of the stirred fluid volume. Velocity profiles generated from the simulations were used to predict and compare the performance of the two designs. To validate the CFD model, the simulation results were compared with experimental results from existing work and a satisfactory agreement was established. It was concluded that the counter-axial flow impeller could provide better turbulence characteristics that would improve the quality of mixing systems.

Hydrodynamics of the Interceptor Analysis Via Both Ultrareduced Model Test and Dynamic Computational Fluid Dynamics Simulation

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
M. Mansoori ◽  
A. C. Fernandes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Degrees Of Freedom ◽  
Experimental Tests ◽  
Dynamics Simulation ◽  
Navier Stokes ◽  
Current Channel ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Method ◽  
Hydrodynamic Effects

This work investigates the hydrodynamic effects of introducing interceptors on fast vessels. Interceptors are vertical flat blades installed at the bottom of the stern vessel. They cause changes in pressure magnitudes around the vessel bottom and especially at the end of the hull where they are located. The pressure variations have an effect on resistance, draft height, and lifting forces which may result in a better control of trim. This work uses a combination of computational fluid dynamics (CFD) and ultrareduced experimental tests. The investigation applies the Reynolds-averaged Navier–Stokes (RANS) equations to model the flow around the ultrareduced model with interceptors with different heights. Our model is analyzed based on a finite-volume method using dynamic mesh. The boat motion is only with two degrees-of-freedom. The results show that the interceptor causes an intense pressure gradient, decreasing the wet surface of the vessel and, quite surprisingly, the resistance. At last, this paper shows that, within a range, a better trim control is possible. The height of the interceptor has an important effect on interceptor efficiency, and it should be especially selected according to the length of the vessel and boundary layer thickness at the transom. The ultrareduced model tests were performed in the Current Channel of the Laboratory of Waves and Current of COPPE/UFRJ (LOC in Portuguese acronym).

scholarly journals What does computational fluid dynamics tell us about intracranial aneurysms? A meta-analysis and critical review

2019 ◽  
Vol 40 (5) ◽  
pp. 1021-1039 ◽  
Author(s):  
Khalid M Saqr ◽  
Sherif Rashad ◽  
Simon Tupin ◽  
Kuniyasu Niizuma ◽  
Tamer Hassan ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Intracranial Aneurysms ◽  
Meta Analysis ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Fundamental Properties ◽  
Cfd Models ◽  
Computational Fluid Dynamics Cfd ◽  
Supplementary Material

Despite the plethora of published studies on intracranial aneurysms (IAs) hemodynamic using computational fluid dynamics (CFD), limited progress has been made towards understanding the complex physics and biology underlying IA pathophysiology. Guided by 1733 published papers, we review and discuss the contemporary IA hemodynamics paradigm established through two decades of IA CFD simulations. We have traced the historical origins of simplified CFD models which impede the progress of comprehending IA pathology. We also delve into the debate concerning the Newtonian fluid assumption used to represent blood flow computationally. We evidently demonstrate that the Newtonian assumption, used in almost 90% of studies, might be insufficient to describe IA hemodynamics. In addition, some fundamental properties of the Navier–Stokes equation are revisited in supplementary material to highlight some widely spread misconceptions regarding wall shear stress (WSS) and its derivatives. Conclusively, our study draws a roadmap for next-generation IA CFD models to help researchers investigate the pathophysiology of IAs.

scholarly journals STATORS USE INFLUENCE ON THE PERFORMANCE OF A SAVONIUS WIND ROTOR USING COMPUTATIONAL FLUID DYNAMICS

2011 ◽  
Vol 10 (1-2) ◽  
pp. 63
Author(s):  
J. V. Akwa ◽  
A. P. Petry
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Cylindrical Shape ◽  
Tip Speed Ratio ◽  
Eddy Viscosity Model ◽  
Computational Fluid Dynamics Cfd ◽  
The Moment ◽  
Volume Method

This paper aims at verifying the influence of using five kinds of stators in the averaged moment and power coefficients of a Savonius wind rotor using computational fluid dynamics (CFD). The analyzed stators have cylindrical shape with two and three openings, one and four deflector blades and walls shaped like a wings. The equations of continuity, Reynolds Averaged Navier-Stokes – RANS and the Eddy Viscosity Model k-ω SST, in its Low-Reynolds approaches, with hybrid near wall treatment; are numerically solved using the commercial software Star-CCM+, based on Finite Volume Method, resulting in the fields of pressure and velocity of the flow and the forces acting on the rotor buckets. The moment and power coefficients are achieved through integration of forces coming from the effects of pressure and viscosity of the wind on the buckets device. The influence of the stators use in the moment and power coefficients is checked by changing the geometry of the device for each simulations series, keeping the Reynolds number based on rotor diameter equal to 433,500. The obtained values for averaged moment and power coefficients indicate that for each type of stator used, there was maximum performance for a given tip speed ratio of rotor. Improvement in performance over the operation without stator was obtained only to the operations using stator with four deflector blades and to the stator with cylindrical shape with three openings. The improvement percentage in performance obtained for the best condition (use of four deflector blades at tip speed ratio equal to 1) is 12% compared to the performance of the rotor operating without stator.

scholarly journals THE ANALYSIS OF FLUID DYNAMICS OF WAVE POWER STATION WITH WELLS TURBIN BY CFD

2020 ◽  
Vol 57 (6A) ◽  
pp. 1
Author(s):  
Thien Tich TRUONG ◽  
Sang Quang Nguyen ◽  
Bang Kim Tran
Keyword(s):  
Fluid Dynamics ◽  
Renewable Energy Sources ◽  
Axial Flow ◽  
Navier Stokes ◽  
Natural Vibrations ◽  
Wells Turbine ◽  
Navier Stokes Equation ◽  
Air Chamber ◽  
Natural Energy ◽  
Blade Shape

Natural energy such as wind, wave and other natural vibrations is one of the high potential renewable energy sources. The Wells turbine is based on the use of bidirectional turbines, which act as axial-flow self-rectifying turbines that employs a symmetrical blade profile and rotating unidirectionally in reciprocating airflows generated by the air chamber to extract energy from vibrations. These topics have been extensively studied both numerically and experimentally such as research on the parameters of the effects of structure, angle of attack, blade shape, etc. In this paper, numerical simulation is carried out using commercially available tool Fluent for fluid dynamics analysis and focus on oscillating predictions, with particular attention to the behavior of the flow. Based on the Numerical Wave Tank (NWT) model is simulated in a two dimensional used in this model, which is constructed mainly based on the spatially averaged Navier Stokes equation with the k-ε model for simulating the turbulence and modeled with Volume of Fluid (VOF). Axial-flow turbines system and future development as well as the proposed limitations will be discussed in detail.

scholarly journals Numerical Investigation of Hydrodynamics Induced by a Pitched Blade Turbine: Effect of the Shape of Vessel Base

Mechanika ◽  
2019 ◽  
Vol 25 (5) ◽  
pp. 370-376 ◽  
Author(s):  
BELHANAFI Abdelghani
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Turbulent Model ◽  
Stirred Tanks ◽  
Navier Stokes Equation ◽  
Stirred Vessel ◽  
Pitched Blade Turbine ◽  
Hydrodynamic Structure

This paper presents an numerical analysis influence of bottom shape on the hydrodynamic structure for cylindrical stirred vessel with bump. The turbulent flow generated in stirred tanks is numerically predicted by the resolution of the Navier-Stokes equation using standard k-ε turbulent model. Several parameters on the mixture efficiency has been investigated. Particularly, we have studied the bottom shape of the tank, which is the distance between the bump-turbine with down pumping direction  and impeller diameter.  The numerical obtained results of the CFD (computational fluid dynamics) code CFX V13.0 with the MRF (Multi Reference Frame) are presented in order to understand the flow structure. The three components velocity profiles and the turbulent kinetic energy dimensionless distributions obtained at bottom tanks with three different heights are analyzed and discussed. From these results, we can confirm that including a bump at the bottom center of the tank closer to the turbine improves significantly the operating conditions of stirring and mixing. Predictions have been compared with literature data and a satisfactory agreement has been found.

scholarly journals A Numerical Study of Spray Strips Analysis on Fridsma Hull Form

Fluids ◽  
2021 ◽  
Vol 6 (11) ◽  
pp. 420
Author(s):  
Samuel ◽  
Andi Trimulyono ◽  
Parlindungan Manik ◽  
Deddy Chrismianto
Keyword(s):  
Fluid Dynamics ◽  
Numerical Study ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Total Resistance ◽  
Navier Stokes Equation ◽  
Computational Fluid Dynamics Cfd ◽  
Wetted Surface Area ◽  
Volume Method ◽  
Dynamics Problems

Spray strips are deflectors added to the hull to reduce the Wetted Surface Area (WSA). The reduced WSA will decrease the total ship drag caused by the deflection of the spray strip installation. The research aimed to predict the function of the spray strip to improve ship performance using Computational Fluid Dynamics (CFD). The numerical approach in this study used the Finite Volume Method (FVM) with the RANS (Reynolds-averaged Navier–Stokes) equation to solve fluid dynamics problems. VOF (Volume of Fluid) was used to model the water and air phases. The results of this study indicated that the number of spray strips would have a significant effect compared to without using a spray strip. Spray strips with three strips could reduce the total resistance by 4.9% at Fr 1.78. Spray strips would increase the total resistance value by 2.1% at low speeds. Spray strips were effective for reducing total resistance at Fr > 1 or the planing mode conditions. The total resistance prediction used three suggestion profiles with the best performance to reduce total resistance by 6.0% at Fr 1.78.

scholarly journals Application of non-linear k-e turbulence model in flow simulation over underwater axisymmetric hull at higher angle of attack

2011 ◽  
Vol 8 (2) ◽  
pp. 149-163 ◽  
Author(s):  
R Sakthivel ◽  
S Vengadesan ◽  
S K Bhattacharyya
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Autonomous Underwater Vehicle ◽  
Angle Of Attack ◽  
Cross Flow ◽  
Flow Simulation ◽  
Underwater Vehicle ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Non Linear

This paper addresses the Computational Fluid Dynamics Approach (CFD) to simulate the flow over underwater axisymmetric bodies at higher angle of attacks.  Three Dimensional (3D) flow simulation is carried out over MAYA Autonomous Underwater Vehicle (AUV) at a Reynolds number (Re) of 2.09×106. These 3D flows are complex due to cross flow interaction with hull which produces nonlinearity in the flow. Cross flow interaction between pressure side and suction side is studied in the presence of angle of attack. For the present study standard k-ε model, non-linear k-ε model models of turbulence are used for solving the Reynolds Averaged Navier-Stokes Equation (RANS). The non-linear k-ε turbulence model is validated against DARPA Suboff axisymmetric hull and its applicability for flow simulation over underwater axisymmetric hull is examined. The non-linear k-ε model performs well in 3D complex turbulent flows with flow separation and flow reattachment.  The effect of angle of attack over flow structure, force coefficients and wall related flow variables are discussed in detail. Keywords: Computational Fluid Dynamics (CFD); Autonomous Underwater Vehicle (AUV); Reynolds averaged Navier-Stokes Equation (RANS); non-linear k-ε turbulence modeldoi: http://dx.doi.org/10.3329/jname.v8i2.6984   Journal of Naval Architecture and Marine Engineering 8(2011) 149-163

Sign in / Sign up

Export Citation Format

Share Document