Studies on increasing the efficiency of industrial flow control structures

The Bernoulli principle states that the rapid increase in flow velocity leads to a reduction in pressure or potential energy in the system or vice versa. Valves can also be used to slow down or stop high-speed flows which increases pressure in the system and material damage may occur if high pressure countermeasures are not established or the systems contain air volume before they are in operation. Air pocket can be accumulated at the top of the pipes where the system is hovering. Air volume or bubbles can lead to additional pressure and strain in the system. Air valves have been developed for the purpose of reducing pressure safely and evacuating air and also vacuuming additional air due to the system's lower pressure situation. The air valves are generally made up of moving/floating parts. These valves discharge the air collected in the torso by open flaps or orifices due to the flow compression. Air valve can also provide with the potential to absorb the pressurized air that the system requires by working reversibly. Floating balls or buoys are used as control mechanisms in such systems. After the air evacuation is completed in the air valve, buoys are floated with the rising of the fluid and provide full sealing of the system again. Air valves are used in the required systems, but the suitability of these valves is improved by building new prototypes tested with experimental methods for the specific systems. This method has a large cost and it requires long-time periods for research and development studies. Other than the experimental techniques, it is possible to examine the behavior of fluids in advanced computer simulations with high accuracy which is enough to guide the design procedures practically. Computational Fluid Dynamics (CFD) provides valid results when the model parameters are validated for this air valve product. In this study, one of the main aim is to determine the air evacuation and vacuum capacity of the single-ball four-function air valve which is produced by Doğuş Vana company. The multiphase and dynamic CFD models were built using ANSYS FLUENT software. The results indicate that, both pressurized domain, moving solid parts due to density difference of the fluids (gravity) and multiphase (air/water) domain is possible to simulate in a single model, providing an effective platform to investigate and improve the performance of air valves. And also in the further chapters of this study, a general comparison is seeking about the usage of CFD for predicting butterfly valve performance with specifying the various flap and body designs of valves, discuss meshing methods to improve results and learn how to reduce instant pressure drops and main head loss which is occurred due to butterfly valve's presence in the flow system. Researches on changing the design of DN1800 butterfly valve's flap is done which is produced by Doğuş Valve Company to reduce the local pressure loss and to determine the obtainable benefit by CFD analysis. In the process of these applications, limits of valve design are followed according to designations of the company and factors such as weight and strength were taken into consideration. Valves are convenient for usage in the pipelines, but the suitability of these valves is improved by creating prototypes by experimental methods for the specific systems. It is possible to examine the behavior of fluids in advanced computer simulations with high accuracy which is enough to guide design procedures practically with today's technology. The method called as Computational Fluid Dynamics (CFD) provides valid results with the model parameters are appropriate for these valve products. Keywords: Air valve, Butterfly Valve, Computational Fluid Dynamics, CFD, Head Loss, Pressure drops and changings, Pipeline systems, Air evacuation and vacuum capacities, ANSYS, Fluent solver