This master thesis project has been carried out in cooperation with the Endress+Hauser Flowtec AG in Switzerland. The project was part of a bigger predevelopment project for a vortex flow meter in the research and development department of Endress+Hauser. Prowirl (vortex) flow meters are often used for measuring the volume flow in steam applications. This measurement method is based on the phenomena of vortices occurring behind obstacles in a stream which are registered by a sensor. Aim of the project was to develop and test a new vortex flow transducer concept for highest pressure applications (line pressure of 250 bars). Endress+Hauser already had a sensor for such applications which was outdated and not compatible to the newer generation of sensors. Two concepts with and without a temperature sensor option have been generated. The concepts have been modeled and verified via FE-analysis and analytical calculations according to the relevant standards (ASME Boiler and Pressure Vessel Code and EN 13445). After the calculations prototypes have been manufactured and tested. The conducted tests matched the simulations well and proved that the concept worked. More detailed tests after this thesis project are necessary to transfer the concept into a final product. However, it has been shown that the new concept has significant advantages over the existing highest pressure sensor. These are a bigger pressure range, the option of integrating a temperature sensor and a cost reduction for the flow meters compared to the existing design. Keywords: Vortex, Flow meter, Sensor, Water hammer / Detta examensprojekt har utförts i samarbete med Endress+Hauser Flowtec AG i Schweiz. Projektet har varit en del av ett större inledande projekt kring en virvelflödesmätare under avdelningen för forskning och utveckling hos Endress+Hauser. Prowirl(virvel)flödesmätare används ofta för mätning av volymflöde i ångapplikationer och tekniken bygger på sensorregistrering av fenomenet virvelbildning som uppstår nedströms hinder i ett flöde. Målet med projektet var att utveckla och testa en ny virvelflödesmätare för högtrycksapplikationer (ledningstryck upp till 250 bar). Sensorn som Endress+Hauser redan hade för sådan applikation var föråldrad och inte kompatibel med nyare generationer av sensorer. Två koncept har tagits fram, ett med och ett utan temperatursensor. Koncepten har modellerats och verifierats genom FEM och analytiska beräkningar enligt relevanta standarder (ASME Boiler and Pressure Vessel Code och EN 13445), efter vilket prototyperna tillverkats och testats. De utförda testerna överensstämde väl med simulationerna och bevisade att koncepten fungerade. Mer utförliga tester efter detta examensprojekt är nödvändigt för att med koncepten som utgångspunkt skapa en klar produkt. Men det har visats att dessa koncept har väsentliga fördelar över den befintliga högtryckssensorn. Bland dem kostnadsreducering, möjlighet för integrering av temperatursensor och breddat tryckspann jämfört mot den existerande designen. Nyckelord: Virvel, Flödesmätare, Sensorer, Vattenslag

Hydropower plants have the ability to go from a full load to no load in just a few seconds. In order to go from full load to no load in a few seconds the flow is controlled by movement of guide vanes. At fault detection the guide vanes closes quickly for safety reasons. This causes hydraulic transients in the waterways, which leads to a pressure rise in the spiral case and a pressure drop in the draft tube.   There have been a few accidents related to these quick closures of the guide vanes where the runner blades break and entire power stations are damaged. These incidents are caused by a full column separation in the draft tube. An early sign of a full column separation is large cavities. The main objective of this degree project is to analyse the effects of a quick closure of the guide vanes and to make a guide book of how to find indications of large cavities when performing closure tests. Data taken from commissioning and status tests for several turbines were analysed.   In conclusion, the guide book of how to find indications of large cavities will help analyse the results of a quick closure of the guide vanes. Due to the unique appearance of pressure transients for each power station this guide book will not be enough for a complete analyse of a closing test. Although, it will help to notify when there is a need for further analyses by expert personnel.