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Testing of Nozzles
Foldyna, Josef ; Sitek, Libor ; Ščučka, Jiří ; Klich, Jiří ; Hlaváček, Petr
Based on the request made by the company NET Ltd. Staré Město pod Sněžníkem, tests of quality of nozzles for generation of high-speed water jet were performed at the Department of material disintegration of the Institute of Geonics AS CR, v. v. i., in Ostrava. Three nozzles provided by NET were tested. The nozzles were marked as nozzle CKM – A, nozzle CKM – B, and nozzle ACMK. The nozzle quality was evaluated by the determination of their discharge coefficient at various operating pressures and by visual inspection of the quality of the nozzle and the water jet.
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Vlastnosti trysek – experimentální ověření na zažízení stavěném pro výzkum šroubovicových nestabilit
Tesař, Václav ; Kellnerová, Radka ; Kukačka, Libor ; Kordík, Jozef
Nozzle characterisations in current use may be described as zero-order (neglected loss) and first-order (constant loss coefficient). The first author (V. Tesar) introduced in 1985 a second-order theory, fully predicting all the variations of nozzle properties with Reynolds number Re. The basic idea is an assumption of the loss being entirely specified by displacement effect of wall boundary layer in the exit. The other assumption is the layer thickness being governed by laminar boundary layer growth law. All evidence for this theory so far was only indirect. This paper presents recent direct experimental verification by measurements of boundary layer profiles on a large-scale nozzle model across a wide range of Re. The predictions of the 1985 model are fully supported.
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Hydraulics of overflowed bridge
Chára, Zdeněk ; Vlasák, Pavel
The paper deals with an open channel flow around model of a bridge when the water depth is higher than height of the bridge opening. Both the pressured flow through bridge opening and free surgace flow over the model were studied. For both cases discharge coefficients were determined and for overflowed model also the velocity profiles were measured to evaluate the ratio of discharges going below and over the bridge model.
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