In: Journal of Hydrology and Hydromechanics, vol. 63, no. 1
Sape A. Miedema
Detaily:
Rok, strany: 2015, 1 - 12
Kľúčové slová:
Slurry transport; Homogeneous transport; Viscous sub layer; Mixing length.
URL originálneho zdroja: http://www.ih.savba.sk/jhh
O článku:
Slurry transport in horizontal and vertical pipelines is one of the major means of transport of sands and gravels
in the dredging industry. There exist 4 main flow regimes, the fixed or stationary bed regime, the sliding bed regime, the
heterogeneous flow regime and the homogeneous flow regime. Of course the transitions between the regimes are not
very sharp, depending on parameters like the particle size distribution. The focus in this paper is on the homogeneous
regime. Often the so called equivalent liquid model (ELM) is applied, however many researchers found hydraulic
gradients smaller than predicted with the ELM, but larger that the hydraulic gradient of liquid. Talmon (2011, 2013)
derived a fundamental equation (method) proving that the hydraulic gradient can be smaller than predicted by the ELM,
based on the assumption of a particle free viscous sub-layer. He used a 2D velocity distribution without a concentration
distribution.
In this paper 5 methods are described (and derived) to determine the hydraulic gradient in homogeneous flow, of
which the last method is based on pipe flow with a concentration distribution. It appears that the use of von Driest
(Schlichting, 1968) damping, if present, dominates the results, however applying a concentration distribution may
neutralise this. The final equation contains both the damping and a concentration distribution giving the possibility to
calibrate the constant in the equation with experimental data. The final equation is flexible and gives a good match with
experimental results in vertical and horizontal pipelines for a value of ACv = 1.3. Data of horizontal experiments Dp =
0.05 – 0.30 m, d = 0.04 mm, vertical experiments Dp = 0.026 m, d = 0.125, 0.345, 0.560, and 0.750 mm.
Ako citovať:
ISO 690:
Miedema, S. 2015. A head loss model for homogeneous slurry transport for medium sized
particles. In Journal of Hydrology and Hydromechanics, vol. 63, no.1, pp. 1-12. 0042-790X (until 2019) .
APA:
Miedema, S. (2015). A head loss model for homogeneous slurry transport for medium sized
particles. Journal of Hydrology and Hydromechanics, 63(1), 1-12. 0042-790X (until 2019) .