Date of Award

20-5-2024

Document Type

Thesis

School

School of Mechanical Engineering

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr.S.Nadaraja Pillai

Keywords

Extended Flat Plate Trailing Edge, Serrated Trailing Edge, Downstream Velocity, Wake Intensity, Power Spectral Density

Abstract

The wake behaviour of extended flat plate (EFP) and serration in the trailing edge of S809 airfoil is presented in this experimental study using wind tunnel testing for several freestream turbulence intensities (TI). The clustering wind turbines in wind parks has recently been an important problem, as it involves determining the number of wind turbines to be installed to increase the power output.

The downstream wake characteristics are one of the most significantparameter that influence the performance of subsequent wind turbines.These wind turbine blades are made up of airfoil cross sections and need to be studied in detail. A series of wind tunnel experiments have been conducted to assess the downstream near-wake characteristics of the S809 airfoil at different angles of attack corresponding to the Reynolds number (Re) = 2.11 × 105.

These experimental results discovered the complex flow behaviors of the downstream near-wake characteristics, featuring significant irregularity arising from the chaotic flow separations dominating over the suction sides of the airfoil.This phenomenon influenced to increasing velocity deficit at post stall region. Based on the experimental results, it is found that the velocity deficit increase from TI 10% to 12% makes the optimal TI as 10% only.

Nonetheless, as the extended trailing-edge amplitude (A) increases, all the downstream velocity profiles broaden significantly, and the non-dimensional vortex shedding frequencies decrease. The base model with serration model wave length (λ) = 0.2C, A = 0.1C shows significant changes in wake intensity downstream. Furthermore, experiments were conducted to better understand the wake characteristics at various downstream locations such as 1C, 2C, 3C, and 4C axial chord.

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