magistrsko delo magistrskega študijskega programa II. stopnje Strojništvo
Romana Krek (Author), Martin Petkovšek (Mentor), Marko Hočevar (Co-mentor)

Abstract

Pri enojno reguliranih Francisovih črpalnih turbinah se izven optimalnega področja obratovanja zaradi sekundarnih tokov na izhodu iz gonilnika ustvari vrtinec. Vrtinec povzroča nizkofrekvenčne tlačne pulzacije, te pa vibracije in hrup. Tlačne pulzacije in vrtinec imajo isto lastno frekvenco, ki je običajno med 20 % in 40 % hitrosti vrtenja gonilnika. Pri nezadostni sesalni višini prične vrtinec kavitirati in tako postane viden. Takrat ga imenujemo kavitacijski vrtinec. Za izbrani model Francisove turbine smo eksperimentalno opredelili obratovalne točke, kjer se kavitacijski vrtinec pojavi. Opredelili smo, kako vrtinec izgleda, in pomerili tlačne pulzacije, ki jih povzroči. V nalogi so predstavljene prve meritve absolutnega statičnega tlaka znotraj kavitacijskega vrtinca. Za meritve tlaka v kavitacijskem vrtincu je bil izdelan poseben merilni sistem. Glede na različne izbrane točke obratovanja smo izmerili absolutni statični tlak v kavitacijskem vrtincu, ki je znašal od 90 mbar do 260 mbar. Meritve so bile izvedene po standardu IEC 60193 v laboratoriju za turbinske stroje na merilni postaji za merjenje modelov turbin tipa Francis.

Keywords

magistrske naloge;Francisove črpalne turbine;kavitacijski vrtinec;tlak;tlačne pulzacije;meritve;delna obremenitev;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FS - Faculty of Mechanical Engineering
Publisher: [R. Krek]
UDC: 621.224.24(043.2)
COBISS: 16837915 Link will open in a new window
Views: 857
Downloads: 193
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Other data

Secondary language: English
Secondary title: Measurements cavitation vortex rope pressure pulsations in a Francis pump turbine model
Secondary abstract: At single-regulated Francis pump turbines a vortex rope is created outside the optimal operating range due to a swirling flow at the runner outlet. The vortex causes low-frequency pressure pulsations, more over vibrations and noise. Pressure pulsations and vortex rope have the same rotating frequency, which is usually between 20 % and 40 % of the rotational speed of the runner. In case of insufficient suction height the vortex rope begins to cavity and thus becomes visible and it is called cavitation vortex rope. For the selected model of the Francis pump turbine we have experimentally identified the operating points where the cavitation vortex rope is created. We defined how the vortex looks and the values of pressure pulsations that are generated by the vortex rope. In the paper are also presented the first results measuring the absolute static pressure inside the cavitation vortex rope. For the pressure measurements inside the cavitation vortex rope a special measurement system was developed. Depending on the different selected operating points, the measured absolute static pressure readings ranged from 90 mbar to 260 mbar. Measurements were carried out according to IEC 60193 standard at a laboratory for turbine machines at a test rig for measuring Francis type turbine models.
Secondary keywords: Francis pumps turbine models;cavitation vortex rope;pressure pulsations;measurements;part load;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. Ljubljana, Fak. za strojništvo
Pages: XXIII, 78 str.
ID: 11211691