Experimental investigation of a miniature bladeless turbine

• Main Author: Teo, Chin Guan.
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Mechanical engineering::Motors, engines and turbines
• Online Access: http://hdl.handle.net/10356/50927
• Institution: Nanyang Technological University

In this Final Year Project, two miniature Tesla turbines of different sizes were designed and fabricated. One turbine consisted of rotor discs which were 120 mm in diameter, while the other comprised 80 mm diameter discs. Sufficiently strong materials were chosen to suit the purpose of using compressed air as the working fluid. The stator assembly was fabricated using thick acrylic to ensure that failed parts remain contained within the turbine chamber in the event of breakage. The rotor assembly is made up of an aluminium shaft and washers, and steel clamp collars. Standard CDs were used as rotor discs; it had been advised that these CDs would be able to sustain speeds of approximately 20 000 revolutions per minute (rpm). This is in excess of our experimental requirements, where the rpm is not expected to exceed 5000. The designed bladeless turbines were then implemented in conjunction with a Power Generation Unit (PGU) that contains a wall of wire coil and a magnet. By Faraday's law, induced voltage will be produced when the rotor assembly rotates. Rotary mechanical energy is thereby converted into useful electrical energy. The open-loop induced voltage is measured using a multimeter and its variation may be observed using an oscilloscope. It has also been shown that the designed turbine is able to power simple electrical devices such as LEDs. Experiments were performed to identify the effects on various parameters on the output voltage, and hence, useful power. The variables that were examined in our series of experiments include inlet pressures of 50, 100, 150 or 200 kPa, four, six, eight or ten rotor discs, each with either two, four or eight exhaust holes. Sidewalls with two, four or eight exhaust ports were also on trial. The effect of inter-disc spacing - 0.3, 0.5, 1.0, 2.0 and 3.5 mm, as well as the diameters of rotor discs, were also studied. Experimental investigations reveal the most favourable configuration is such that the turbine contains ten rotor discs of 80 mm diameter, with each disc having eight exhaust holes. Similarly, there should be eight exhaust outlets on the sidewall, and the inter-disc gap could lie between about 1.4 to 2.0 mm. Additionally, higher pressures generated more greater useful power.