Design of atomizers and burners for coal water slurry combustion. Quarterly report, January 1, 1996--March 31, 1996
A novel extensional rheotester was developed to measure the extensional properties of aqueous solutions of Polyacrilamide {number_sign}10 and coal water slurries (CWS). When a drop of viscoelastic liquid or CWS containing additives is allowed to form at the end of a capillary tube, it starts to fall once its weight exceeds the retaining force exerted by surface tension. In experiments with aqueous solutions of Polyacrilamide it was observed that a long filament of fluid connected the droplet to the end of the capillary tube. The filament partially supported the droplet slowing its rate of fall. In order to evaluate the transient elongational stresses an elongational viscosity that are developed in the long threads of liquid before breakup, the mass (m), the diameter (D), the velocity (V) and the acceleration (a) of the suspended droplet along with the diameter of the filament (d) are measured. The length of the trailing filament is also measured as a function of time in order to determine the filament stretch rate {dot {epsilon}}. The time dependent behavior of the filament diameter was also measured using a laser attenuation technique. The strain rate of the filament was determined from the experimental values of {dot L}/L and {minus}2{dot d}/d, where the dot refers to differentiation with respect to time. Seven different aqueous solutions of Polyacrilamide E10 were prepared spanning a wide range of polymer concentration (0.5{percent}, 0.25{percent}, 0. 125{percent}, 0.0625{percent}, 0.03125{percent}, 0.015625{percent}, 0. 0078125{percent}). The data gave a single relaxation time for each solution. This relaxation time for uniaxial extension is found to increase with E10 concentration. 4 refs., 10 figs., 2 tabs.
- Research Organization:
- Carnegie-Mellon Univ., Pittsburgh, PA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-95PC95105
- OSTI ID:
- 288436
- Report Number(s):
- DOE/PC/95105-T2; ON: DE96050253
- Resource Relation:
- Other Information: PBD: [1996]
- Country of Publication:
- United States
- Language:
- English
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