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Technical Issues
1/2015 pp. 13-21

Badania numeryczne mechanicznego usuwania termicznej warstwy przyściennej dla nieskończonej kaskady łopatek skrobiących


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Streszczenie

The aim of the study is to examine the impact of the gap between the tip of the scraping blade (scraper) and the wall on the heat transfer. Numerical simulations of heat transfer and fluid flow under mechanical removing of thermal boundary layer were conducted. Due to the complexity of the phenomenon calculations were simplified to the two-dimensional case. As a test case a heat transfer under removing thermal boundary layer via infinite, rectangular scrapers cascade was chosen. Calculations were carried out for different scraper heights, ie. for different gap values. Reynolds and Grashof numbers were constant and equalled 1000 and 10 000 respectively. The range of Prandtl number and the gap varied 0.7-56.0 and 0.005L-0.25L accordingly. The results showed that heat transfer intensification increases with the increasing Prandtl. It was shown that gap value strongly influences both temperature distribution and heat transfer rate. With the decreasing gap heat transfer rate increases.

Słowa kluczowe

heat transfer, thermal boundary layer scraping

Literatura

1. Bergles, A.E., Heat transfer enhancement - the encouragement and accomodation of high heat fluxes, Transactions of the ASME, 1997, Vol. 119, pp. 8-19.

2. Stręk, F., Mieszanie i mieszalniki. Warszawa, Wydawnictwa Naukowo-Techniczne, 1981.

3. Skoczylas, A., Hydrodynamika i wnikanie ciepła w wymiennikach cienkowarstewkowych, wąskoszczelinowych i skrobakowych, Wrocław, Oficyna Wydawnicza Politechniki Wrocławskiej, 2001.

4. Moallemi, M.K., Jang K.S., Prandtl number effects on laminar mixed convection heat transfer in a lid-driven cavity, International Journal of Heat and Mass Transfer, 1992, 35(8), pp. 1881-1892.

5. Ansys CFX, Ansys CFX Solver Modelling Guide v. 14.5, 2014.