Setup of a 3D printed wind tunnel: application for calibrating bi-directional velocity probes used in Fire Engineering Applications

Description

The research presented here focuses on the development of a 3D printed wind tunnel and the relevant equipment to be used for calibrating bi-directional velocity probes (BDVP). BDVP are equipment to be used for measuring velocity flow by determining the pressure difference of hot gases generated during fires. The manufactured probes require calibration to determine the calibration factor to achieve precise measurement. The calibration is usually performed in wind tunnels which can be difficult to access due to costs, complexity and the various pieces of equipment required. The aim of the current study is to develop and assemble an inexpensive and easy-to-build bench-scale wind tunnel, with a data-logging system and fan control functionalities for fast and effective calibration of BDVP. A 3D printer with a PET-G filament is used, able to produce parts for the wind tunnel system which are durable and easy to handle and assemble. The system additionally includes an Arduino-based measuring unit with a hot-wire anemometer and temperature correction: Rev. P. This takes precise measurements; continuously logging data on a computer through a USB interface and capable of saving data on an SD card. This design provides users with parameters of velocity flow up to 4 m/s with standard deviation of 1.2 % and turbulence intensity of 1 %. The main advantages of this wind tunnel are its simplicity to build and portability. The dataset contains design files for 3d printing of the wind tunnel, BOM and wiring of electronic components. The project is prototype under development and authors are not responsible for any damages or injuries caused by inappropriate construction or operation. This source is distributed WITHOUT ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE.

Steps to reproduce

The current small-scale low-speed wind-tunnel setup consists of three units: the wind-tunnel, the control and the measuring unit connected to the PC which provides appropriate airflow velocity up to 5 m/s. The wind tunnel unit parts are printed using a 3D PRUSA MK3S Printer with a 0.3 mm resolution. PET-G was selected as a material for its superior mechanical properties that include increased durability, strength and ease in further manufacturing e.g., drilling, gluing, cutting, etc. The wind tunnel unit is divided and printed in parts according to the requirements of the 3D printer. After printing, parts are glued and sealed using silicone. The main benefits of the 3D printing of wind-tunnel parts are the ease of construction, assembly and ease of customization in case of further development. 3D printing is also suitable for more complicated and sophisticated parts, e.g., the diffuser of these wind tunnels that would have been difficult to build under conventional construction techniques. The electronic circuit included components which are easily accessible in local shops or in e-shops. Only part that might be difficult to obtain is the velocity sensor Rev.P that can be ordered from the US or UK. The measuring unit is based on Arduino UNO with an LCD 16x2 monochromatic display for visualization of current velocity and Datalogger Shield for storing data on an SD card without connecting to a PC. Arduino is popular in prototyping for its user-friendly application, large community support and large number of tutorials and source codes determining it as the best solution for special application in fire engineering. The Arduino provides the possibility to connect a measuring unit to a PC through a USB port and store data online on the computer Arduino’s Serial Monitor.

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