Local turbulent energy dissipation rate in an agitated vessel: experimental and turbulence scaling

0484246 - ÚH 2019 RIV RU eng J - Journal Article
Ditl, P. - Šulc, R. - Pešava, V. - Jašíková, D. - Kotek, M. - Kopecký, V. - Kysela, Bohuš
Local turbulent energy dissipation rate in an agitated vessel: experimental and turbulence scaling.
Theoretical Foundations of Chemical Engineering. Roč. 52, č. 1 (2018), s. 122-134. ISSN 0040-5795. E-ISSN 1608-3431
R&D Projects: GA ČR GA16-20175S
Grant - others:GA MŠk(CZ) LO1201
Institutional support: RVO:67985874
Keywords : turbulence * mixing * particle image velocimetry * turbulent energy dissipation rate * energy spectrum function * Rushton turbine
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 0.520, year: 2018

The hydrodynamics and the flow field in an agitated vessel were measured using 2-D time resolved particle image velocimetry (2-D TR PIV). The experiments were carried out in fully baffled cylindrical flat bottom vessels 300 and 400 mm in inner diameter. The 300 mm inner diameter tank was agitated by a Rushton turbine 100 mm in diameter, and the 400 mm inner diameter tank was agitated by a Rushton turbine 133 mm in diameter. Three liquids of different viscosities were used as the agitated liquid: (i) distilled water (nu = 9.35 x 10(-7) m(2)/s), (ii) a 28 vol % aqueous solution of glycol (nu = 2 x 10(-6) m(2)/s), and (iii) a 43 vol % aqueous solution of glycol (nu = 3 x 10(-6) m(2)/s). The velocity fields were measured at an impeller rotation speed in the range from 300 to 850 rpm, which covers the Reynolds number range from 50000 to 189000. This means that fullydeveloped turbulent flow was reached. The experiments were performed to investigate the applicability of the following relations: epsilon* = epsilon/(u (4)/nu) = const, vK/u = const, I >/eta K = const, tau(I >)/tau(K) = const, epsilon* = epsilon/((Nd)4/nu) = const, I >/d ae Re-1, eta K/d ae Re-1, vK/(Nd) = const, N tau(I >) ae R-1, N tau(K) ae Re-1, and epsilon/(Nq) ae Re. These formulas were theoretically derived in our previous work, using turbulence theory, in particular, using turbulence spectrum analysis. The correctness of the proposed relations is investigated by statistical hypothesis testing.
Permanent Link: http://hdl.handle.net/11104/0281874