Advanced design and optimization of wind turbines based on turbine theories

Zh Zhang

doi:10.1088/1755-1315/431/1/012021

Abstract

A review of wind turbine technology showed that many flaws in both the flow models and computations are involved in the traditional fundamentals. While traditional methods for design and computation are all based on the airfoil theory, a new method based on turbine theories has been developed and is shown to be ideally applicable. Against the traditional method, the new method also considers non-uniform pressure distribution in flows downstream of the rotor plane and is thus highly accurate. The blade efficiency or tip swirl number has been introduced. It enables computation of the power coefficient to be very reasonable. Its optimum can be directly applied to the geometrical design of turbine blades. Between the tip speed ratio X, blade efficiency e, and power coefficient cp, a closed solution of both the optimum design and the operation of wind turbines exists. It is demonstrated that the maximum achievable power coefficient can be 10% larger than that predicted by all previous theories.

Highlights

In times of increased use of renewable energies, wind energy is gaining increased attention
Aerodynamic designs of wind turbines are uniquely based on airfoil theory, to which apply the Schmitz theory and the blade element momentum method (BEM) [1, 2]
The Schmitz theory and the BEM suppose that the flow through the turbine wheel is comparable to the flow passing through a single blade as treated by the airfoil theory

Summary

Introduction

In times of increased use of renewable energies, wind energy is gaining increased attention. Based on the mechanical principle, use of the momentum law to determine the flow resistance requires that a control volume around a disc must be given by real streamlines. This condition is obviously not fulfilled in figure 1. The flow model shown in figure 1 must be considered as the first flaw or defect in the fundamentals of wind power technology. This must be considered as the second flaw or defect in the fundamentals of wind power technology.

Turbine theory and applications

Findings

Maximum power coefficient and flows