CFD Simulation for Turbulent Flow Past NACA4412 Aerofoil

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
C. Manjunath ◽  
G.H. Somesha ◽  
Sekhar Majumdar
Keyword(s):  
Fluid Dynamics ◽  
Reynolds Number ◽  
Turbulent Flow ◽  
High Speed ◽  
Cfd Simulation ◽  
Measurement Data ◽  
Curvilinear Coordinates ◽  
Flow Past ◽  
Wide Range ◽  
Low Reynolds

The complex fluid dynamics of different flow situations at low Reynolds number for natural flying objects like birds and insects, needs to be clearly understood for arriving at an optimum design for sizes ranging from the small man-made ones to very large size high speed commercial aircrafts or the fighter aircrafts. Airfoil performance at low Reynolds numbers impacts the performance of a wide range of systems. Computational Fluid Dynamics (CFD) tools have been around for a couple of decades now. With the superfast growth of computing power, speed and accuracy of these mathematical tools have improved to a considerable extent. However, any CFD simulation employing turbulence models needs to be validated against reliable and accurate measurement data obtained from wind tunnels. The present work focuses on 2D numerical simulation of turbulent flow past a symmetric NACA4412 aerofoil, using C- grid topology, for a Reynolds number of 1 million and 3 million. The computation uses the CFD code RANS3D, an implicit, pressure-based finite volume type Reynolds averaged Navier-stokes solver in generalized non-orthogonal curvilinear coordinates.

scholarly journals An assessment of the laminar kinetic energy concept for the prediction of high-lift, low-Reynolds number cascade flows

2011 ◽  
Vol 225 (7) ◽  
pp. 995-1003 ◽  
Author(s):  
R Pacciani ◽  
M Marconcini ◽  
A Arnone ◽  
F Bertini
Keyword(s):  
Reynolds Number ◽  
Kinetic Energy ◽  
High Speed ◽  
Low Reynolds Number ◽  
Flow Region ◽  
Freestream Turbulence ◽  
High Lift ◽  
Numerical Predictions ◽  
Wide Range ◽  
Low Reynolds

The laminar kinetic energy (LKE) concept has been applied to the prediction of low-Reynolds number flows, characterized by separation-induced transition, in high-lift airfoil cascades for aeronautical low-pressure turbine applications. The LKE transport equation has been coupled with the low-Reynolds number formulation of the Wilcox's k − ω turbulence model. The proposed methodology has been assessed against two high-lift cascade configurations, characterized by different loading distributions and suction-side diffusion rates, and tested over a wide range of Reynolds numbers. The aft-loaded T106C cascade is studied in both high- and low-speed conditions for several expansion ratios and inlet freestream turbulence values. The front-loaded T108 cascade is analysed in high-speed, low-freestream turbulence conditions. Numerical predictions with steady inflow conditions are compared to measurements carried out by the von Kármán Institute and the University of Cambridge. Results obtained with the proposed model show its ability to predict the evolution of the separated flow region, including bubble-bursting phenomenon and the formation of open separations, in high-lift, low-Reynolds number cascade flows.

scholarly journals Multirotor Drone Aerodynamic Interaction Investigation

Drones ◽  
2018 ◽  
Vol 2 (4) ◽  
pp. 43 ◽  
Author(s):  
Dhwanil Shukla ◽  
Narayanan Komerath
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Low Reynolds Number ◽  
Performance Measurements ◽  
Factors Affecting ◽  
Wide Range ◽  
Wake Interactions ◽  
Low Reynolds ◽  
And Performance ◽  
Thrust And Torque

Aerodynamic interactions between rotors are important factors affecting the performance of in-plane multirotor Unmanned Air Vehicles (UAVs) or drones, which are the majority of small size UAVs (or mini-drones). Optimal design requires knowledge of the flow features. The low Reynolds number of many UAV rotors raises the question of how these features differ from those expected by traditional analytical methods for rotorcraft. Aerodynamics of a set of side-by-side rotors in hover over a range of rotor separation and Reynolds number is studied using high-speed Stereo Particle Image Velocimetry (SPIV) and performance measurements. The instantaneous and time-averaged SPIV data presented here indicate an increase in inter-rotor wake interactions with decrease in rotor spacing and Reynolds number. A dip in rotor efficiency at small rotor spacing at low Reynolds number is observed through thrust and torque measurements. The basic components of in-plane multirotor wake and velocity profiles are identified and discussed to help generalize the findings to a wide range of drones. However, the data provide confidence in traditional analysis tools, with small modifications.

Low Reynolds number flow past a transverse cylinder at Mach two.

AIAA Journal ◽  
1972 ◽  
Vol 10 (10) ◽  
pp. 1381-1382
Author(s):  
CLARENCE W. KITCHENS ◽  
CLARENCE C. BUSH
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Flow Past ◽  
Number Flow ◽  
Low Reynolds

Steady approach of unsteady low-Reynolds-number flow past two rotating circular cylinders

2013 ◽  
Vol 736 ◽  
pp. 414-443 ◽  
Author(s):  
Y. Ueda ◽  
T. Kida ◽  
M. Iguchi
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Stokes Equations ◽  
Low Reynolds Number ◽  
Vortex Method ◽  
The Self ◽  
Circular Cylinders ◽  
Far Field ◽  
Flow Past ◽  
Low Reynolds

AbstractThe long-time viscous flow about two identical rotating circular cylinders in a side-by-side arrangement is investigated using an adaptive numerical scheme based on the vortex method. The Stokes solution of the steady flow about the two-cylinder cluster produces a uniform stream in the far field, which is the so-called Jeffery’s paradox. The present work first addresses the validation of the vortex method for a low-Reynolds-number computation. The unsteady flow past an abruptly started purely rotating circular cylinder is therefore computed and compared with an exact solution to the Navier–Stokes equations. The steady state is then found to be obtained for $t\gg 1$ with ${\mathit{Re}}_{\omega } {r}^{2} \ll t$, where the characteristic length and velocity are respectively normalized with the radius ${a}_{1} $ of the circular cylinder and the circumferential velocity ${\Omega }_{1} {a}_{1} $. Then, the influence of the Reynolds number ${\mathit{Re}}_{\omega } = { a}_{1}^{2} {\Omega }_{1} / \nu $ about the two-cylinder cluster is investigated in the range $0. 125\leqslant {\mathit{Re}}_{\omega } \leqslant 40$. The convection influence forms a pair of circulations (called self-induced closed streamlines) ahead of the cylinders to alter the symmetry of the streamline whereas the low-Reynolds-number computation (${\mathit{Re}}_{\omega } = 0. 125$) reaches the steady regime in a proper inner domain. The self-induced closed streamline is formed at far field due to the boundary condition being zero at infinity. When the two-cylinder cluster is immersed in a uniform flow, which is equivalent to Jeffery’s solution, the streamline behaves like excellent Jeffery’s flow at ${\mathit{Re}}_{\omega } = 1. 25$ (although the drag force is almost zero). On the other hand, the influence of the gap spacing between the cylinders is also investigated and it is shown that there are two kinds of flow regimes including Jeffery’s flow. At a proper distance from the cylinders, the self-induced far-field velocity, which is almost equivalent to Jeffery’s solution, is successfully observed in a two-cylinder arrangement.

Stability of the Low Reynolds Number Compressible Flow Past a NACA0012 Airfoil

AIAA Journal ◽  
2021 ◽  
pp. 1-15
Author(s):  
Laura Victoria Rolandi ◽  
Thierry Jardin ◽  
Jérôme Fontane ◽  
Jérémie Gressier ◽  
Laurent Joly
Keyword(s):  
Reynolds Number ◽  
Compressible Flow ◽  
Low Reynolds Number ◽  
Naca0012 Airfoil ◽  
Flow Past ◽  
Low Reynolds

The Effect of Reynolds Number and Velocity Distribution on LP Turbine Cascade Performance

1986 ◽  
Author(s):  
D. J. Patterson ◽  
M. Hoeger
Keyword(s):  
Reynolds Number ◽  
Pressure Distribution ◽  
Guide Vane ◽  
Flow Visualisation ◽  
Suction Surface ◽  
Trailing Edge ◽  
Wide Range ◽  
Oil Flow ◽  
Low Reynolds ◽  
Lp Turbine

Because of the laminar boundary-layer’s inability to withstand moderate adverse pressure gradients without separating, profile losses in LP turbines operating at low Reynolds numbers can be high. The choice of design pressure distribution for the blading is thus of great importance. Three sub-sonic LP turbine nozzle-guide-vane cascade profiles have been tested over a wide range of incidence, Mach number and Reynolds number. The three profiles are of low, medium and high deflection and, as such, display significantly different pressure distributions. The tests include detailed boundary-layer traverses, trailing-edge base-pressure monitoring and oil-flow visualisation. It is shown that the loss variation with Reynolds number is a function of pressure distribution and that the trailing-edge loss component is dominant at low Reynolds number. The importance of achieving late flow transition — rather than separation — in the suction-surface trailing-edge region is stressed. The paper concludes by remarking on the advantages and practical implications of each loading design.

scholarly journals Influence of inlet air distributor geometry on the fluid dynamics of conical spouted beds: A CFD study

2018 ◽  
Vol 24 (4) ◽  
pp. 369-378 ◽  
Author(s):  
J.N.M. Batista ◽  
R.C. Brito ◽  
R. Béttega
Keyword(s):  
Fluid Dynamics ◽  
Cfd Simulation ◽  
Low Cost ◽  
Scale Up ◽  
Straight Tube ◽  
Spouted Bed ◽  
Bed Height ◽  
Spouted Beds ◽  
Wide Range ◽  
Solid Dynamics

The spouted bed presents limitations in terms of scale-up. Furthermore, its stability depends on its geometry as well as the properties of the fluid and solid phases. CFD provides an important tool to improve understanding of these aspects, enabling a wide range of information to be obtained rapidly and at low cost. In this work, CFD simulation was used to evaluate the effects of different inlet air distributors (Venturi and straight tube) and the effects of static bed height on the fluid and solid dynamics of a conical spouted bed. Simulations were performed using the two-dimensional Euler-Euler approach. In order to evaluate the fluid dynamics model, static pressure data obtained by simulation were compared with experimental data obtained with the Venturi distributor. The fluid and solid dynamics of the conical spouted bed were obtained by CFD simulation. The results showed that the pressure drop was lower for the straight tube air distributor, while the Venturi air distributor provided higher stability and a more homogenous air distribution at the bed entrance.

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