Results 1 - 10 of 14552
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[en] The steam turbine blades are subjected to the natural permanent wear or damage, which may be of mechanical or metallurgical origin. The typical damage occurring during the lifetime of turbine blading may be erosion, corrosion, foreign objects damage, rubbing and cracking caused by high cycle fatigue and creep crack growth. The nozzle and diaphragm vanes (stationary blades) of the steam turbine are elements whose damage is commonly occurring and they require special repair processes. The damage of the blade trailing edge of nozzle and diaphragm vanes, due to the former causes, may be refurbished by welding deposits or stainless steel inserts welded to the blades. Both repair methods of the stationary steam turbine blades are presented. The results of the blades refurbishment are an increase of the turbine availability, reliability and efficiency, and a decrease of the risk that failure will occur. Also, the repair cost versus the spare blades cost represent significant reduction of expenditure. 7 refs
[en] The author furnishes a review of incidents of major damage to high-output steam turbines. At the same time, he thereby underlines the call for an improvement in the exchange of experience on such damage and its causes at international level. Only the careful observance of past damage experience - including that of foreign manufacturers and operators - complete and modern monitoring equipment and the painstaking evaluation of all data furnished by such equipment can keep the risk of new technical development within economically tolerable limits. (orig.)
[de]Der Verfasser dieses Berichtes gibt einen Ueberblick ueber Grossschaeden an Dampfturbinen groesster Leistung. Er verbindet damit die Forderung nach einer Verbesserung des Erfahrungsaustausches ueber Schaeden und ihre Ursachen. Nur die sorgfaeltige Beachtung der bisherigen Schadenerfahrungen - auch auslaendischer Hersteller und Betreiber -, moderne Ueberwachungseinrichtungen und die gewissenhafte Bewertung aller Hinweise dieser Einrichtungen koennen das Risiko neuer technischer Entwicklungen in wirtschaftlich tragbaren Grenzen halten. (orig.)
[en] The Index Tests have been used for many years to obtain the optimized cam correlation between wicket gates and runner blades for double regulated turbines (Kaplan, bulb). The cam is based on homologous model tests and is verified by site measurements, as model tests generally do not reproduce the exact intake configuration. Index Tests have also a considerable importance for checking of the relative efficiency curve of all type of turbines and can demonstrate if the prototype efficiency curve at plant condition has the shape expected from the test of the homologues model. During the Index Tests measurements the influence of all losses at multiple points of turbine operation can be proved. This publication deals with an overview on the Index Tests made after modernization of large bulb units in Iron Gates II - Romania. These field tests, together with the comparative, fully homologous tests for the new hydraulic shape of the runner blades have confirmed the smooth operational behavior and the guaranteed performance. Over the whole 'guaranteed operating range' for H = 8m, the characteristic of the Kaplan curve (enveloping curve to the propeller curves), agreed very well to the predicted efficiency curve from the hydraulic prototype hill chart. The new cam correlation have been determined for different head and realised in the governor, normally based on model tests. The guaranteed, maximum turbine output for H = 7,8m is specified with 32, 5 MW. The maximum measured turbine output during the Index Tests on cam operation was 35,704 MW at the net head of 7,836 m. This corresponds to 35,458 MW for the specified head H= 7, 8 m. All these important improvements ensure a significant increase of annual energy production without any change of the civil construction and without increasing the runner diameter. Also the possibility to increase the turbine rated output is evident.
[en] The paper contains the short description of the design process of the axial flow turbines for Small Hydro. The crucial elements of the process are: ARDES programme for 1D inverse problem (containing the statistic information of the well performed hydraulic units, applying the lifting aerofoil theory); determination of universal hill diagram and optimization of the runner blades geometry by utilization of the 3D CFD codes. As the result of design process with utilization of both design steps, the generated runner blades geometry (1D inverse problem) and some computational results of 3D CFD solver have been presented. As the conclusion some crucial remarks of the designed process have been brought forward.
[en] During manufacture and assembly of steam and gas turbine blades there are always some technological deviation and is meant local increase or decrease in dimension at certain sections of the profile improper stagger angle of long blades during assembly etc. In this paper the effect of oversize in dimensions at certain important places along a reaction profile has been studied. The technological deviation has been made by sticking thin aluminium foils of 0.3 mm thickness and 15 mm width at inlet and exit tips of reactive profiles and its effect on aerodynamic efficiency at mach. nos ranging from 0.7 to 1.1. The object of performing these tests was to obtain comprehensive data based on which information suitable tolerances could be recommended during manufacture of these blades