DESIGN SIMULATION ON ULTRASONIC WAVES BASED VORTEX FLOWMETER FOR FLOW VELOCITY ESTIMATION

• Main Author: Zatalini, Nadila
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/79598
• Institution: Institut Teknologi Bandung

Fluid flow velocity is an important parameter in many applications. Fluid flow is used to ensure that fluid goes to the right place and time. Utilization of fluid flow is required in strict quality control, occupational health and safety, and efficiency. One tool for measuring fluid flow is vortex flowmeter. Vortex flowmeter is measuring instrument used to determine amount of flow and works based on principle of generating a vortex behind bluff body. In commercial vortex flowmeters, a pressure sensor is installed. If sensitivity of pressure sensor is low, a large bluff body is needed. Vortex is generated from both sides of bluff body. Usually only one pressure sensor is inserted into pipe wall which detects only up or down vortex behind bluff body. As a result, only one side of vortex is detected so that sensitivity of system is reduced. With these shortcomings, ultrasonic waves-based vortex flowmeters were developed. Ultrasonic waves were chosen because they have slower waves speeds than electromagnetic waves, making it easier to measure time and variable delay information. Ultrasonic transducers are installed on upstream (before bluff body) and downstream (after bluff body) side of flow. Ultrasonic waves that propagate on upstream and downstream sides cause a difference in travel time Difference in travel time can be further processed to determine fluid flow velocity. In this design simulation, vortex flow simulation and ultrasonic vortex flow measurement simulation are performed. Vortex flow simulation was carried out on water and air fluids at a temperature of 25°C and a pressure of 1 atm. Fluid flow is laminar and incompressible. Fluid properties that are taken into account are dynamic density and viscosity. Shape of bluff body is circle and rectangle. Simulation of ultrasonic vortex flow measurement was carried out on gas fluid flow in a closed pipe with variations in bluffness coefficient on bluff body. Results of vortex flow simulation show that when vortex is formed, fluid flow velocity increases but fluid pressure decreases. Bluff body shape affects number of vortexes. Number of vortexes in circular bluff body is more than rectangular bluff body. Density and dynamic viscosity of fluid have no direct effect on number of vortexes. Simulation of ultrasonic vortex flow measurement with variations in bluffness coefficient value of 1.1; 1,2; 1.3; 1.4; 1.5 was carried out to obtain graph of vortex frequency against volumetric flow rate, graph of ultrasonic waves velocity on downstream side against vortex frquency, graph of waves travel time on downstream side against vortex frequency, and graph of inlet flow velocity against difference in travel time. Simulation results show that there is a vortex flow indicated by slowing of ultrasonic waves travel time on downstream side. Difference in travel time is zero, meaning there is no vortex flow. Difference in travel time is greater than zero, which means that there is vortex flow. This research is a simulation study. It is hoped that results of this study will serve as basis for development of an ultrasonic waves-based vortex flowmeter.