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Title: Experimental and theoretical study of the viscous shear pneumatic torque motor
Author: Stewart, Colin D.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1989
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This work describes a feasibility study of a new concept in pneumatic turbomachinery. The concept has its origins in the Tesla turbine with a set of closely spaced, flat discs on a shaft. Fluid flows through the gaps between the discs and exerts a force on the disc faces by viscous shear. In this new concept, plates are positioned in the disc spaces to restrict the flow in one direction round the rotor. It is explained that this design offers certain advantages over conventional pneumatic drives for position control applications such as robotics and the feasibility study has focused on this application. A theoretical analysis is presented which indicated that the disc spaces need to be very small to limit the flowrate and a consequence of this is that the restrictor plates are flexible due to their thin size. A multiple disc motor and a single disc motor which were built are described and their performance compared with theoretical predictions. The plates in the multiple disc motor experienced instability and an experimental and theoretical investigation of this problem is presented. The developent of the theoretical analysis is described, beginning with static and quasi-steady models. The final formulation of the problem considers an unsteady, compressible, laminar flow through a straight, high aspect ratio rectangular duct containing a perfectly flexible membrane. The governing equations are solved by numerical methods. A two-step Lax-Wendroff method was employed but proved to be numerically unstable. The method of characteristics proved to be successful and is the solution method used in a computed survey of membrane stability in a thin duct. The implication of the theoretical and experimental results on the feasibility of the viscous shear torque motor for use in position control is discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available