Large-Eddy Simulation of the Aerodynamic and Aero-Acoustic Performance of an Industrial Fan Designed for Tunnel Ventilation

2012 ◽  
Author(s):  
Domenico Borello ◽  
Stefano Bianchi ◽  
Alessandro Corsini ◽  
Franco Rispoli ◽  
Anthony G. Sheard
Keyword(s):  
Large Eddy Simulation ◽  
Unsteady Aerodynamics ◽  
Secondary Flows ◽  
Reverse Direction ◽  
Grid Turbulence ◽  
Ambient Conditions ◽  
Tunnel Ventilation ◽  
Eddy Simulation ◽  
Aerodynamic Properties ◽  
Large Eddy

The development of industrial fans traditionally relies upon the use of empirical correlations and experimental analyses to validate both aerodynamic and acoustic aspects of fan performance. This paper presents the development of a computational based method focused on the prediction of unsteady aerodynamics and modeling of aero-acoustic sources. The authors applied the study to a single fan from a new range of large tunnel ventilation axial flow fans. The fan specification required mechanical and aerodynamic properties that would enable it to operate in the forward direction under ambient conditions to provide cooling air to the tunnel under routine operation, and in the reverse direction at 400°C under emergency conditions in the event of a tunnel fire. The final aerodynamic and mechanical design was additionally required to generate no more than 80 db during reverse operation, to ensure members of the emergency service could still communicate in the event of a fire. The simulations were carried out using the open source code Open-Foam, within which the authors implemented a (Very) Large Eddy Simulation (V)LES based on an one-equation sub-grid scale SGS model to solve a transport equation for the modeled (sub-grid) turbulent kinetic energy. This improvement of the sub-grid turbulence model is here considered as a remedial strategy in VLES of high-Reynolds industrial flows able to tackle the otherwise insufficient resolution of turbulent spectrum. The VLES of the industrial fan permits to detect the flow features such as three-dimensional separation and secondary flows. Predicted noise emissions, in terms of sound pressure level spectra, are compared with experimental results, and found to agree within the uncertainty of the measurements.

Large-Eddy Simulation of a Tunnel Ventilation Fan

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Domenico Borello ◽  
Alessandro Corsini ◽  
Giovanni Delibra ◽  
Mario Fiorito ◽  
Anthony G. Sheard
Keyword(s):  
Large Eddy Simulation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Unsteady Aerodynamics ◽  
Pressure Rise ◽  
Secondary Flows ◽  
Computational Method ◽  
Tunnel Ventilation ◽  
Eddy Simulation ◽  
Large Eddy

In this paper we discuss a computational method focused on the prediction of unsteady aerodynamics, adequate for industrial turbomachinery. Here we focus on a single rotor device selected from a new family of large tunnel ventilation axial flow fans. The flow field in the fan was simulated using the open source code OpenFOAM, with a large-eddy simulation (LES) approach. The sub-grid scale (SGS) closure relied on a one-equation model, that requires us to solve a differential transport equation for the modeled SGS turbulent kinetic energy. The use of such closure was here considered as a remedial strategy in LES of high-Reynolds industrial flows, being able to tackle the otherwise insufficient resolution of turbulence spectrum. The results show that LES of the fan allows to predict the pressure rise capability of the fan and to reproduce the most relevant flow features, such as three-dimensional separation and secondary flows.

Large Eddy Simulation on the Unsteady Aerodynamics of a Heavy Duty Truck in Wind Gust

2011 ◽  
Author(s):  
Makoto Tsubokura ◽  
Prasanjit Das ◽  
Tomofuyu Matsuuki ◽  
Takuji Nakashima
Keyword(s):  
Large Eddy Simulation ◽  
Numerical Method ◽  
Unsteady Aerodynamics ◽  
Static Condition ◽  
Wind Tunnels ◽  
Wind Gust ◽  
Heavy Duty ◽  
Heavy Duty Truck ◽  
Eddy Simulation ◽  
Large Eddy

Unsteady aerodynamic forces acting on a full-scale heavy duty truck were investigated using a large-eddy simulation technique. The numerical method adopted was first validated on a static condition measured at the DNW German-Dutch wind tunnels. After the correction of the blockage ratio in the wind tunnel, the drag coefficient obtained by our numerical method showed good agreement with the experimental data within the errors of less than 5%. Effect of an air deflector mounted on the top of a cabin was also discussed. Then the method was applied to non-stationary conditions in which the truck was subjected to ambient perturbation of approaching flow. The perturbation of the flow is a model of atmospheric turbulence and sinusoidal crosswind velocity profiles were imposed on the uniform incoming flow with its wavelength comparable to the vehicle length. As a result, it was confirmed that when the wavelength of the crosswind is close to the vehicle length, averaged drag increases by more than 10% and down-force decreases by about 60%, compared with the case without perturbation.

Large Eddy Simulation and CDNS Investigation of T106C Low-Pressure Turbine

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Site Hu ◽  
Chao Zhou ◽  
Zhenhua Xia ◽  
Shiyi Chen
Keyword(s):  
Large Eddy Simulation ◽  
Flow Separation ◽  
Separated Flow ◽  
Low Pressure ◽  
Secondary Flows ◽  
Computational Domain ◽  
Suction Surface ◽  
Low Pressure Turbine ◽  
Eddy Simulation ◽  
Large Eddy

This study investigates the aerodynamic performance of a low-pressure turbine, namely the T106C, by large eddy simulation (LES) and coarse grid direct numerical simulation (CDNS) at a Reynolds number of 100,000. Existing experimental data were used to validate the computational fluid dynamics (CFD) tool. The effects of subgrid scale (SGS) models, mesh densities, computational domains and boundary conditions on the CFD predictions are studied. On the blade suction surface, a separation zone starts at a location of about 55% along the suction surface. The prediction of flow separation on the turbine blade is always found to be difficult and is one of the focuses of this work. The ability of Smagorinsky and wall-adapting local eddy viscosity (WALE) model in predicting the flow separation is compared. WALE model produces better predictions than the Smagorinsky model. CDNS produces very similar predictions to WALE model. With a finer mesh, the difference due to SGS models becomes smaller. The size of the computational domain is also important. At blade midspan, three-dimensional (3D) features of the separated flow have an effect on the downstream flows, especially for the area near the reattachment. By further considering the effects of endwall secondary flows, a better prediction of the flow separation near the blade midspan can be achieved. The effect of the endwall secondary flow on the blade suction surface separation at the midspan is explained with the analytical method based on the Biot–Savart Law.

scholarly journals Predicting Unsteady Loads in Marine Propulsor Crashback Using Large Eddy Simulation

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Hyunchul Jang ◽  
Aman Verma ◽  
Krishnan Mahesh
Keyword(s):  
Large Eddy Simulation ◽  
Reverse Flow ◽  
Reverse Direction ◽  
Unsteady Forces ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Mean ◽  
Submarine Hull ◽  
Marine Propulsor ◽  
Good Agreement

Propulsor crashback is an off-design operating condition where a propulsor rotates in the reverse direction to yield negative thrust. Crashback is characterized by the interaction of the free stream with the reverse flow generated by propulsor rotation. This causes a highly unsteady vortex ring which leads to flow separation and unsteady forces and moments on the blades. Large eddy simulation (LES) is performed for marine propulsors in crashback for various configurations and advance ratios and validated against experiments. The predictive capability of LES as a tool for propulsor crashback is demonstrated on an open propulsor, open propulsor with a submarine hull, and ducted propulsor with and without stator blades. LES is in good agreement with experiments for the mean and RMS levels, and spectra of the unsteady loads on the propulsors.

Large Eddy Simulation of Diesel Spray Combustion With a Multi-Component Drop Vaporization Model

2017 ◽  
Author(s):  
Xiaohua Ren ◽  
Lei Zhang ◽  
Zhongli Ji
Keyword(s):  
Experimental Data ◽  
Large Eddy Simulation ◽  
Combustion Process ◽  
Dynamic Structure ◽  
Diesel Spray ◽  
Grid Turbulence ◽  
Fuel Droplets ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Les Model

Large-eddy simulation (LES) of diesel spray and combustion was performed to study its improvement in the simulation of engine in-cylinder dynamics compared to the Reynolds-averaged simulation. For the LES, the dynamic structure approach was used to model the sub-grid turbulence and its interaction with the moving droplets in the spray. A multicomponent vaporization model (MCV) based on the continuous thermodynamics approach and a gamma distribution to describe the distribution of the numerous fuel components, was used to simulate the vaporization of diesel fuel droplets. The MCV model was imbedded into the LES framework in the KIVA-4 program. Using this LES model, a non-evaporative spray in a constant-volume chamber was first simulated. More realistic spray structures and improved agreements in the spray penetration with the experimental data were obtained by the LES compared to a Reynolds-averaged simulation of the same spray. A further simulation of an evaporative diesel spray and the subsequent combustion process using both LES and MCV models was also performed. Improved agreements with the experimental data in the spray structures and soot distributions were also observed using both models.

Investigation of Particle-Laden Flow in a Straight Duct Using Large Eddy Simulation

2007 ◽  
Author(s):  
M. Fairweather ◽  
J. Yao
Keyword(s):  
Large Eddy Simulation ◽  
Fluid Phase ◽  
Particle Dispersion ◽  
Secondary Flows ◽  
Solid Particles ◽  
Duct Flow ◽  
Mean Flow ◽  
Two Phase ◽  
Eddy Simulation ◽  
Large Eddy

A particle-laden turbulent flow in a square duct is predicted using large eddy simulation (LES). The simulation is performed for a Reynolds number of 35,500, and correctly predicts the existence of secondary flows and their effects on the mean flow. The results are also in good qualitative agreement with experimental data obtained at different Reynolds numbers. One-way coupling is assumed between solid particles and the fluid, and a particle equation of motion, including Stokes drag, lift, buoyancy and gravity force terms, solved using a Lagrangian particle tracking technique. Three sizes of particle (1, 50 and 100 μm) are considered, and results demonstrate that size has a significant effect on particle dispersion and deposition in the duct flow. As particle size increases, therefore, they tend to settle on the floor of the duct, with less dispersion in the fluid phase. The study demonstrates the usefulness of LES for nuclear waste processing applications since secondary flows occur in many practically-relevant flows, and since it is desirable that the two-phase waste mixture is kept as homogeneous as possible to prevent, or at least discourage, the settling out of solid particles to form a bed which can promote pipe blockages.

Large eddy simulation of flow around a reverse rotating propeller

2013 ◽  
Vol 729 ◽  
pp. 151-179 ◽  
Author(s):  
Hyunchul Jang ◽  
Krishnan Mahesh
Keyword(s):  
Large Eddy Simulation ◽  
Vortex Ring ◽  
Free Stream ◽  
Reverse Flow ◽  
Separated Flow ◽  
High Amplitude ◽  
Reverse Direction ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Impact

AbstractThis paper studies the flow around a propeller rotating in the reverse direction in a uniform free stream. Large eddy simulation is used to study this massively separated flow at a Reynolds number of 480 000 and advance ratios $J= - 0. 5$, $- 0. 7$ and $- 1. 0$. Simulations are performed on two grids; statistics of the loads and velocity field around the propeller show encouraging agreement between the two grids and with experiment. The impact of advance ratio is discussed, and a physical picture of the unsteady flow and its influence on the propeller loads is proposed. An unsteady vortex ring is formed in the vicinity of the propeller disk due to the interaction between the free stream and the reverse flow produced by the reverse rotation. The flow is separated in the blade passages; the most prominent is the separation along the sharp edge of the blade on the downstream side of the blade. This separation results in high-amplitude, transient propeller loads. Conditional averaging is used to describe the statistically relevant events that determine low- and high-amplitude thrust and side-forces. The vortex ring is closer and the reverse flow induced by propeller rotation is lower when the loads are high. The propeller loads scale with $\rho {U}^{2} $ for $J\lt - 0. 7$ and with $\rho {n}^{2} {D}^{2} $ for $J\gt - 0. 7$.

Sign in / Sign up

Export Citation Format

Share Document