[en] The patent claim refers to a way to improve the safety device for rotor blades of turbo-engines allowing a simple mounting and dismounting and concerning, above all, the design of that part of the spring which serves as a safety element for the blades. (HP)

No abstract available

[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 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.)

[en] The characteristics of the responses obtained in thermosonic tests are investigated in this study to improve the performance of a thermosonic test system. Thermosonic tests are conducted with an acoustic horn with high power capability to investigate the characteristics of the vibration produced in turbine blades with complex geometry. The influences of the excitation signal that is input to the horn and te coupling methods between a clamp and the acoustic horn on the characteristics of the vibration excited in a component are presented as an excitation method for thermosonic testing. This method can be applied to different types of turbine blades and also to other components

[en] Hydro-Quebec has been using CFD to analyze the performance of its existing turbines for many years. Most of those analyses are based on the measurement of a single runner blade. However, due to manufacturing techniques, in-situ modifications or repairs, there are often small differences between individual blades of the same runner. The impact of this non uniformity was not known thus far and was often assumed to be negligible given the size of the runner. This paper highlights the impact of such differences by presenting the CFD analysis of various blades measured on the same runner. Two different geometries are used for demonstration: the AxialT model propeller and a 50-MW Francis turbine. In both cases, about 50% of the blades could not be considered as representative of the whole turbine and using them could lead to wrong conclusions regarding the turbine performance.

[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] Turbine engine blades and vanes for high-temperature applications are generally cooled by internal passages formed by the investment casting process. The cooling efficiency of the airfoil greatly depends on the removal of the ceramic core used to form the cooling passages. The detection of residual core in blades and vanes for operations above 2000⁰F is difficult with standard visual and x-ray techniques because of the complexity of the cooling passages. A technique using neutron radiography for improved residual core detection has been developed. The contrast is enhanced by ''salting'' the ceramic core base material with a 3 percent concentration of gadolinium oxide. Commercial reactors on the west coast are used for this production inspection. Turnaround time is approximately four days. Special fixtures were designed for both shipping and inspection. Neutron radiography is now a standard production technique for high-temperature engines at Detroit Diesel Allison. Recently this inspection has been made a part of the vendor requirements

[en] Shape optimization requires a proper geometric representation of the blade profile; the parameters of such a representation are usually taken as design variables in the optimization process. However, the designer is more familiar with the traditional design parameters; for turbine blades these would be the leading and trailing edge radii, wedge angles, blade angles, as well as the blades stagger angle, spacing, etc. This work is concerned with the representation of the blade profile in terms of NURBS functions that implicitly satisfy the traditional designer parameters and provide enough flexibility and accuracy to represent any turbine blade shape. This NURBS representation is then tested on two distinct turbine blade shapes to demonstrate the NURBS accuracy and flexibility in capturing a target blade profile or a target blade curvature distribution and area. (author)

[en] Turbine blade has been in service under severe condition such as high temperature, high pressure, corrosive and vibratory environment. Recently its frequent failure occurred and sometimes leaded to unexpected outage which is estimated to cost to several million dollars. In order to prevent blade failure, life assessment technology should be developed and a criteria for replacement of used blade be established. A lot of effort has been made to quantify the damage by using NDE technique and analytical evaluation. In turbine blade, life assessment technology is now well-established in the laboratory but it application to the field is not successful yet due to a lack of accuracy and a difficulty in the field application. Damage type and mechanism of gas turbine blade can be much different depending on operating condition and therefore considering each plant characteristic sufficiently, life assessment method and preventive measure can be properly applied