Design , Performance and Maintenance of Francis Turbines By Hermod Brekke
The aim for turbine design is to increase the efficiency and avoid cavitation and fractures during operation. A brief discussion on a the design philosophy during the last 60 years with will be presented. The structural design has moved from castings and riveted plates to fully fabricated structures of high tensile strength steel in the stationary parts and stainless 13/4 Cr/Ni or 16/5 (17/4) Cr/Ni steel have substituted the 13/1 Cr/Ni in runners. The paper also includes an ancient runner design with plate steel blades moulded in cast steel at crown and band. Such high head runners, put in operation in 1950, hve been in operation in good condition Norway until about 15 years ago. A discussion on stress analyses and fatigue problems of pressure loaded parts and high frequency fatigue in runners, will be presented GJRE-A Classification : FOR Code: 290501 Design, Performance and Maintenance ofFrancis Turbines Strictly as per the compliance and regulations of : Design, Performance and Maintenance of Francis Turbines
Ein nichtrostender Vergütungsstahl mit hohen Festigkeits‐ und Zähigkeitswerten für den Maschinen‐ und Apparatebau
Der martensitisch vergutbare Werkstoff X 4 CrNiMo 165, WNr. 1.4418, findet als nichtrostender walz- und schmiedbarer Stahl aufgrund seiner ausgezeichneten Festigkeits- und Zahigkeitseigenschaften zunehmend Anwendung in mechanisch hochbeanspruchten Teilen des chemischen Apparatebaus und Maschinenbaus. Der Stahl ist bis zu Wanddicken von uber 250 mm gleichmasig durchvergutend. Bei 0,2%-Dehngrenzen uber etwa 800 N/mm2, Zugfestigkeiten von etwa 1000 N/mm2 weist er Kerbschlagarbeitswerte uber 60 J (DVM) bei Raumtemperatur auf. Daruberhinaus weist er hohe Kaltzahigkeit bis −400°C auf. 
 
 
 
Nach sachgemaser Vergutungsbehandlung ist er bestandig gegen selektiven Angriff im Straus-Test nach DIN 50914. 
 
 
 
Er besitzt gute Schweiseignung. 
 
 
 
A martensitic stainless steel with high strength and impact properties for chemical and mechanical engineering purposes 
 
 
 
Within the last few years the low carbon martensitic stainless steel X4CrNiMo 165, WNr. 1.4418, is increasingly used due to it's excellent technological properties. The steel can he offered with tensile strength up to 850 N/mm2 and yield strength up to 1000 N/mm2 together with superior impact properties at room temperature and sub-zero-temperature. So this steel has special significance concerning chemical engineering, where corrosion resistance as well as high tensile and impact values are demanded. 
 
 
 
There is no selective corrosion attack in boiling sulfuric acid (Straus-Test), if the material is quenched and tempered correctly. 
 
 
 
Welding operations may be done without preheating the material.
Shape and surface texture of molten droplets deposited on cold surfaces
When a molten droplet impacts on a cold surface, the interaction between solidification and fluid dynamics can lead to different shapes and surface textures of deposited droplets. This article presents an experimental study on deposition of small droplets (39 μm diameter) of molten wax ink on solid surfaces. Our results show that both the final shape and the surface texture of deposited droplets are extremely sensitive to deposition conditions, which include initial temperature of droplets, type of substrate surface and distance between substrate and printhead. Different surface textures are observed and shown to depend on the thermal and flow histories of ink droplets during the process of impact. A test using crystalline wax reveals crystallization as one of the major factors in determining the final texture.