Articles for februari 2020

KD 699 added

Report KD 699 has been added at the menu KD-reports. The tittle of this report is: “Calculations executed for the 3-bladed rotor of the VIRYA-4.4 windmill (lambda design = 5.25, stainless steel blades) using a 34-pole PM-generator for coupling to a centrifugal pump with a 1.1 kW asynchronous motor”. The 34-pole PM-generator is described in report KD 614.

KD 698 added

Report KD 698 has been added at the menu KD-reports. The tittle of this report is: “The Gö 227 airfoil for use in windmill rotor blades”. This airfoil has a lower side which is partly convex and partly concave and manufacture of windmill blades with this airfoil therefore requires special skills. However, the airfoil has special qualities.

Report R-443-D added

Report R-443-D has been added at the bottom of the menu KD-reports. This report is written by André Hageman in 1980 when he was working at the Wind Energy Group of the University of Technology Eindhoven where I was working too at that time. The report is no longer available but someone has sent me a copy of a scanned version of it which is now available on my website. The tittle of this report is: Catalogue of Aerodynamic Characteristics of Airfoils in the Reynolds number range 10^4 – 10^6. This is an important report as it contains aerodynamic characteristic of a large number of airfoils.

Manuals changed

Originally, the manuals of the VIRYA-1.04, the VIRYA-1.36 and the VIRYA-1.81 were divided into part 1 and part 2. This was done because the file of a complete manual was too large to put it on the website. However, at this moment, a new version of WordPress is used which allows files of 25 Mb. So now the complete manual is given in one file.

KD 532 reviewed

A new chapter 7 has been added to report KD 532 about the VIRYA-3.1 rotor. In chapter 7, the starting torque coefficient has been calculated more accurately using formula 3 out of KD 697.

KD 697 added

Report KD 697 has been added to the menu KD-reports. The tittle of this report is: “Determination of the starting torque coefficient Cqstart for constant chord and tapered blades”. The starting torque coefficient for a tapered blade appears to be about a factor two higher than for a constant chord blade for rotors with the same design tip speed ratio. This report replaces the note “Comparing starting torques – – -” which was written earlier about this subject.

KD 696 added

Report KD 696 can be copied for free from my website at the menu KD-reports. The tittle of this report is: “Summary of the most relevant wind tunnel measurements presented in report R 408 S from 1979, performed on a scale model of the CWD 2740 rotor”.