Development of Unsteady Background-oriented Schlieren System in an Indraft Supersonic Wind Tunnel

To visualize the flow in the test section of an indraft supersonic wind tunnel in the University of Glasgow as long as possible, a background-oriented schlieren system was built up preliminarily. A MATLAB program based on a random dot algorithm developed in this study provides a fully customizable tool to generate background patterns with different sizes and dot densities. Background patterns produced by the in-house developed program then can be printed by a common ink-jet printer. To enhance the signal-noise ratio of the measurement system, white reflective film sheets, or semi-transparent paper can be employed. The correlation algorithm base on fast Fourier transform that is also applicable for PIV was chosen to process background oriented schlieren images. A validation test was performed to visualize the flow structure around a Pitot tube at M = 2.0. The experimental result proves that the BOS system established in this study is capable of visualizing the supersonic flow structure around the Pitot tube and sensitive enough to reveal weak density changes produced by the boundary layer, expansion waves, and weak oblique shock waves. Next, the current BOS system will be improved further by increasing the intensity of light sources to shorten the exposure time, using new cameras with better spatial resolution, and optimizing the background pattern

Investigation of Aerodynamic Interference in a Multirotor by PIV Method

This paper presents part of the investigation into aerodynamics of the vertical take-off and landing multirotor. There are described the technology to design a research object and the Particle Image Velocimetry (PIV) setup to measure airflow around the aircraft. The around-the-aircraft speed distribution was investigated for an angle of attack of 0o and for four different configurations. The results are presented in form of vector velocity field of airflow on the plane of symmetry of the test object. The results enabled the characteristics of speed vs. the distance from the fuselage. It was observed that the push propeller and the main rotor impact the speed field around the fuselage

Investigation of Aerodynamic Interference in a Multirotor by PIV Method

This paper presents part of the investigation into aerodynamics of the vertical take-off and landing multirotor. There are described the technology to design a research object and the Particle Image Velocimetry (PIV) setup to measure airflow around the aircraft. The around-the-aircraft speed distribution was investigated for an angle of attack of 0o and for four different configurations. The results are presented in form of vector velocity field of airflow on the plane of symmetry of the test object. The results enabled the characteristics of speed vs. the distance from the fuselage. It was observed that the push propeller and the main rotor impact the speed field around the fuselage

Computational and Experimental Investigation of Inert Gas Flow Field in Direct Metal Laser Melting Printer Build Chamber

Additive manufacturing methods are becoming more and more popular in today’s production market. These methods became a useful and flexible alternative to traditional manufacturing approach. One of the most popular methods in this family is Direct Metal Laser Melting. It can achieve high quality prints, however, numerous parameters need to be established, to achieve a good quality product. One of the aspects of printing process is inert gas flow. The goal of presented study is to quantitatively assess inert gas flow field using both experimental and numerical methods. Flow field parameters have been measured with anemometry and Particle Image Velocimetry. Additionally Computational Fluid Dynamics tools were used to investigate flow phenomena occurring inside the build chamber. PIV measurements give good insight into the flow field, but they are costly and require significant time for preparation. For this reason, CFD analysis is widely used as a design tool, giving reasonable turnaround time. In addition, every design tool to be reliable need to be validated against test data. In this study the team was able to collect both experimental and numerical data and finally conduct the validation. Work allowed to determine the most suitable approach for predictions in given problem. Different turbulence models have been tested. Simulation results were validated against collected experimental data