ON THE STABILITY OF FLOW IN ROTATING PIPES
Final rept. 1 Apr 1968-1 Apr 1969
ILLINOIS INST OF TECH CHICAGO
Pagination or Media Count:
The stability of flow in rotating pipes is investigated experimentally. The results of the investigation also have a bearing on the stability of flow in the core of swirling flows in stationary ducts and free vortices. Solid body rotation is found to have a destabilizing effect when superposed on a pipe entrance region axial velocity profile. The range of swirl ratios up to four is investigated using two different approaches dye streaks visualization and hot-thermistor anemometry. As the swirl ratio is increased from zero to four, the axial Reynolds number at which laminar flow breaks down decreases from 2500 to 900. These results agree in trend with the limit axial Reynolds number value of 82.9 that was recently obtained by analytical investigations of the stability of a viscous fully developed axial velocity profile subject to a rapid, almost rigid rotation in pipes. The present results also suggest that the destabilizing trend due to solid body rotation may also hold for other axial velocity profiles and indicates a possible new mechanism of confined flow instability that takes place at lower Reynolds numbers than previously believed possible.
- Fluid Mechanics