Wind tunnel design and fabrication for lift force investigation

• Main Author: Ong, Jun Wei
• Other Authors: Yeo Joon Hock
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Aeronautical engineering::Aerodynamics
• Online Access: https://hdl.handle.net/10356/140867
• Institution: Nanyang Technological University

Wind tunnel is a test section, usually large, to simulate the experience of an object when it is undergoing flight by using large industrial fans to move air at high velocity. Researchers and scientist often make use of wind tunnel to learn more about airflow and aerodynamic forces experienced by the object through collation of data. The object using is often a smaller model of the actual vehicle with all the dimensions scaled down appropriately to obtain the most accurate simulation results possible. Fluids such as smoke or dye can injected into the test section during the process for researchers to observe how the air can move around the object. Although wind tunnels are ready available in the market for testing purposes and there are many affordable methods to obtain lift forces on an object, it is more costly to test for both lift and drag forces of an object due to the complexity of its set-up to obtain accurate results. Sting balances are commonly used in the industry to measure both lift and drag forces. Models are being mounted on sting balances, which is usually a long rod connected to the rear end of the model to prevent any disruption of airflow. However, a good and accurate sting balance is very costly. Hence, this project will focus on designing an experiment set-up that is relatively cheaper and suitable for the budget allocated. The target audience for this project will be University Students who will be making use of this designed set-up to learn more about aerodynamic forces and the factors that can affect them. This experiment will also help students internalise the concepts via hands on experience. This report will share more about the process of choosing the right load cell, design and fabrication of the set-up and airfoil to measure both lift and drag. With the set-up ready, it will then be used for the collation of data for lift and drag forces at different angle of attack (AOA) and wind velocity. These data will then be analysed and evaluated to obtain the relationship between lift and drag forces with varying AOA and wind velocities. A step by step explanation on how the experiment was conducted and tweaked to attain the most accurate results possible will all be recorded and discussed in this report. All the data tabulated throughout the course of these experiments will be in the form of graphs. After analysis, it can be concluded that lift force increases when wind speed increase and drag force increases when wind speed increase. It can also be concluded that the lift-coefficient increases with wind velocity until it reaches critical AOA. From these experiments, the drag coefficient does not show any significant trend, and this could be contributed to the size limitation of this experiment set-up. The limitations of this experiment set-up which may lead to indistinct trend would be the size of the wind tunnel and test section which led limited the size of airfoils used. Potential future works on how this set-up can be developed to help students better understand about aerodynamic forces through flow visualisation using aids such as smoke.