Numerical simulations of the aerodynamic response of circular segments with different corner angles by means of 2D URANS. Impact of turbulence modeling approaches

Abstract

This paper presents the results of numerical and experimental investigations on the force coefficients and Strouhal numbers of circular segments considering different corner angles or chord to sagitta ratios. The research is motivated because these geometries are becoming increasingly popular in several engineering disciplines. The so-called D-section (semi-circular cylinder with a corner angle of 90 •) has been experimentally studied in the past, since it is a galloping prone geometry. However, there is a lack of research for cases with different corner angles, and the numerical investigations related to this topic are particularly scarce. In this work, a 2D Unsteady Reynolds Averaged Navier-Stokes approach has been adopted aiming to study the circular segments at the sub-critical regime, considering corner angles from 40 • to 90 • , and the flow parallel to the rectilinear side. These sections were found to be particularly challenging since they present massive flow separation on the rectilinear side, alongside the inherent difficulties related to modeling the flow along curved surfaces at high Reynolds numbers. The impact of introducing low-Reynolds-number and curvature corrections in the k − ω SST turbulence model and the performance of the Transition SST model have been extensively studied.

Numerical simulation and analysis of five-stage lifting pump by improved turbulence model and catastrophe theory

“…Many researchers have studied turbulence and discovered the law of turbulence, which is the variation of energy fluctuation with time-scale or wave number (Chen, Chen, Eyink, & Sreenivasan, 2003;Falkovich & Ryzhenkova, 1992;Frisch, 1995;Liang, Wu, & Zhong, 2017;Young & Read, 2017). So, the other two important variables for the turbulent phase transition are the energy spectrum (E k ) and time index factor (g) (Frisch, 1995;Layek & Sunita, 2018;Montoya, Nieto, Alvarez, Hernandez, & Jurado, 2018;Romero-Gomez, Harding, & Richmond, 2017).…”

Experimental investigation on wind energy harvesting by aeroelastic excitation of a semi-circular cylinder with flat side parallel to the incoming flow

“…Den Hartog [13] was the first to study this geometry's galloping instabilities, while Novak and Tanaka [14] reported the effects on the galloping instability and force coefficients caused by smooth and turbulent flows. Cid Montoya et al [15] addressed the semi-circular cylinder force coefficients and Strouhal number depending on the Reynolds number and the angle of attack. However, no significant study has been published regarding piezoelectric energy harvesting from aeroelastic phenomena present in the semi-circular cylinder at the angles of attack reported herein.…”

“…where f n is a natural frequency of the dynamical system, D is the reference length and St is the Strouhal number that can be measured through aerodynamic wind tunnel tests for each bluff body. In this work, values of the critical Strouhal number for the semi-circular cross-section were taken from Montoya et al [15], and the natural frequencies of the body were measured in the wind tunnel facility to identify the critical VIV flow speed for the sectional models and prototype.…”

“…This parameter, introduced in section 3.3, corresponds to the sum of the drag coefficient and the first derivative of the lift coefficient with respect to the angle of attack. Data for the force coefficients of the semi-circular body were taken from Cid Montoya et al [15]. In order to obtain the a g parameter, a linear estimation of the derivative of the lift coefficient was made, obtaining the value shown in Table 3.…”

Experimental Study for Wind Energy Harvesting Based on the Aeroelastic Excitation of a Semi-Circular Cylinder

“…The objective of this work is to assess the feasibility of a semi-circular cylinder, whose aerodynamic characteristics were previously studied based on experimental tests and numerical simulations [2], to generate large wind-induced oscillations in a classical harvester configuration based on a cantilever beam with the bluff body attached to its tip and a sheet of piezoelectric material bounded close to the fixed end. Other alternative geometries have been studied as tip bluff bodies [3], [4], also considering modifications in the reference shape.…”