Development of a novel rheometric device for the determination of pressure dependent viscosity of non-Newtonian fluids
Akhter, Salma (2000) Development of a novel rheometric device for the determination of pressure dependent viscosity of non-Newtonian fluids. Master of Engineering thesis, Dublin City University.
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A new type of Rheometer has been designed based on hydrodynamic principles Hydrodynamic pressure technique is a relatively new and innovative technique for rheological studies of viscous non-Newtonian fluids. These principles have been extensively used for the last ten years for drawing and coating of strips and wires. The Rheometric Device consists of a rotating inner cylinder (shaft) in a fixed hollow outer cylinder. The complex geometry gap between the two cylinders is filled with a viscous non-Newtonian fluid. When the surface of the shaft is rotating inside the hollow cylinder filled with a viscous fluid, shearing takes place and hydrodynamic pressure develops the magnitude of which is dependent on the shape of the surfaces, the viscosity of the fluid as well as the shear rate 1e the speed with which the inner solid cylinder is rotated. The Rheometer has been developed to determine the Rheological properties of viscous fluid at pressures of up to 100 bar and a shear rate range of 500 to 4000 sec 1.
Experimental procedure and methods have been outlined and a number of experiments have been carried out to determine the effects of pressure and shear rate on viscosity. Included in the work are measurements of the pressure with variation of the shearing speed and inserts. Three different non-Newtonian fluids, glycerine, and silicon with two different viscosities were used as the pressure medium. The experimental works were undertaken with glycerine keeping GO temperature at 18 ± 1 C and silicon at 25+ 1 C for shearing speeds of between 0 25 m/sec-2 0 m/sec. In the present study, theoretical models have been developed based on the non-Newtonian characteristics and a shear rate viscosity relationship was determined using the rheometer at different pressures by comparing the calculated theoretical pressure distribution with the expenmental results.
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