Evaluation of pressure-stiffness coupling in brush seals

Brush seals are comprised of fine diameter fibers densely packed between retaining and backing plates. To achieve seal compliance bristles are arranged to contact rotor with some lay angle. When axial pressure load is applied, bristles interlock and get stuck at the backing plate, and seal stiffness varies under operating conditions. Operating stiffness is critical to determine seal-rotor contact pressure and wear life. Typically, seal stiffness is measured by pressing a curved shoe to brush bore as reported in open literature. Due to the complex nature of pressure-stiffness bristle behavior, static and unpressurized measurements cannot represent actual working seal stiffness. This work presents a brush seal stiffness measurement system that is capable of measuring seal stiffness under working pressure and speed conditions. Rotor speed is achieved by an integrated spindle drive, while contact forces are measured via sensitive load cells. Rotor excursions are applied through lateral motions of the seal housing that is actuated by a motorized linear slide. Stiffness testing methodology and calibration procedure are discussed. Comparative experimental data are presented for both static pressurized and dynamic-pressurized stiffness tests

Aerodynamic performance sensitivity analysis of blade design for a 100 kW HAWT

Wind energy is gaining ever increasing popularity among renewable energy sources. In some European countries installed wind turbine capacity has reached over 20 % of the total power generation capacity. This paper examines aerodynamic performance sensitivity of wind turbine blades for main design variables. The sensitivity analysis has been conducted on a sample 100 kW three-bladed horizontal axis wind turbine (HAWT). Taguchi robust design techniques and orthogonal arrays have been used to perform experimental optimization using five main parameters: airfoil NACA profile, root chord length, tip chord length, root radius and chord profile distribution along the blade’s length. The airfoil profiles and their aerodynamic data are taken from the NACA airfoil database for which experimental lift and drag coefficient data are available. The airfoils for the studied blades have the same profile from root to tip. Three sets of analyses have been performed according to three different base load wind speeds. The sensitivity results have been presented for the optimal tip speed ratio values

Discontinuous feedback stabilization of the angular velocity of a rigid body with two control torques

There has been much interest over the past decade in the problem of asymptotic stabilization of the angular velocity of a rigid body with only two torque inputs. The smooth feedback laws proposed in the literature provide asymptotic stability with nonexponential convergence rates. This paper proposes discontinuous feedback laws to achieve asymptotic stability with exponential convergence rate

An overview of wind turbine manufacturing experience in Turkey

While wind energy has been utilized by windmills for ages, 1970s oil crises was a turning point for many developed governments to initiate massive efforts to develop modern wind turbines. Starting from almost none in early 1980s, the installed wind power capacity has reached 159.2 GW globally by the end of 2009. While the use of wind turbines for general power utilization dates back to 1986 with a 55 kW capacity, it took another decade for wind farms to appear in Turkey. The Electricity Market Regulatory Authority (EPDK) started accepting wind power production licenses in 2007 reaching to a total of 78 GW wind capacity. As of today, the installed wind power capacity of Turkey is 1329 MW. The Electrical Power Resources Survey and Development Administration (EIEI) plans for a total of 20 GW wind energy within 10 years. In line with the global trend, it will be realistic to estimate Turkish wind market to reach 40 GW before 2030. There is extensive industrial infrastructure that will support production of large wind turbines in Turkey. However, due to lack of turbine technology and know-how only a limited portion of this infrastructure is used towards wind turbine production. Recently Ministry of Energy has initiated the National Wind Energy Systems Project (MILRES) with funding from TUBITAK (The Scientific and Technological Research Council of Turkey). The project aims to develop turbine technologies up to 2.5 MWs as well as to coach potential component manufacturers to develop production capabilities for large turbines