Miniature Viscous Disk Pump: Performance Variations From Non-Newtonian Elastic Turbulence

Abstract

Within the present investigation, a miniature viscous disk pump (VDP) is utilized to characterize and quantify non-Newtonian fluid elastic turbulence effects, relative to Newtonian flow behavior. Such deviations from Newtonian behavior are induced by adding polyacrylamide to purified water. The VDP consists of a 10.16 mm diameter disk that rotates above a C-shaped channel with inner and outer radii of 1.19 mm and 2.38 mm, respectively. A channel depth of 230 μm is employed. Fluid inlet and outlet ports are located at the ends of the C-shaped channel. Experimental data are given for rotational speeds of 126 1/s, 188 1/s, 262 1/s, and 366 1/s, pressure rises as high as 700 Pa, and flow rates up to approximately 0.00000005 m3/s. Reynolds number ranges from 2.9 to 6.5 for the non-Newtonian polyacrylamide solution flows and from 51.6 to 149.8 for the Newtonian pure water flows. To characterize deviations due to non-Newtonian elastic turbulence phenomena, two new parameters are introduced, PrR and HCR, where HCR is the ratio of head coefficient (HC) for the polyacrylamide solution and head coefficient for the water solution, and PrR is the ratio of pump power for the polyacrylamide solution and pump power for the water solution. Relative to Newtonian, pure water flows, the polyacrylamide solution flows give pump head coefficient data, dimensional pressure rise data, slip coefficients (SCs), specific speed (SS) values, and dimensional power data, which show significant variations and differences as they vary with flow coefficient (FC) or dimensional volumetric flow rate. Also important are different ranges of specific speed (SS) for the pure water and polyacrylamide solutions, and a lower range of SC or slip coefficient values for the polyacrylamide solution flows, compared to the pure water flows. These variations are due to increased elastic turbulence losses, which occur as viscosity magnitudes increase and the elastic polymers are excited by mechanical stress, which causes them to extend, deform, stretch, and intertwine.

Experimental study on flow and heat transfer enhancement by elastic instability in swirling flow

“…Due to the discrepancy of polymer relaxation time, chain length and molecular weight, different polymers [26,30] induced different onset values of elastic instability/turbulence, leading to various mixing performance. Flow in serpentine channels [24,[31][32][33][34] , porous media [35,36] and self-designed channel [37][38][39] has been recently studied and a consecutive curvilinear streamline is regarded as a necessary condition to trigger elastic instabilities. All these studies showed that the elastic turbulence could indeed benefit the mixing performance.…”

Effects of salinity on the onset of elastic turbulence in swirling flow and curvilinear microchannels

“…In addition, unlike the swirling flow, a steady secondary flow was observed in such a geometry before the onset of elastic turbulence [35]. Besides these standard geometries related to rheometer, elastic turbulence was also triggered in any other geometries, such as porous media [19-21, 36, 37], cross-slot channel [38] and viscous disk pump [39,40]. From these curvilinear geometries, the curvature of the geometry was regarded as an essential condition to induce elastic turbulence or instability.…”

Research on Energy-Efficient Disc Pumps: A Review on Physical Models and Energy Efficiency

“…In addition, it was carried out to change the induced slip by using different levels of surface roughness on the rotating disc [113]. The micro viscous disc pump (VDP) was used to characterize and quantify the elastic turbulence effect of non-Newtonian fluid relative to Newtonian fluid behavior [114,115], as shown in Figure 7.…”