Industrial Steam Turbines - 16 / 20 Pages
Similar to the modularised casing elements, MAN TURBO has standardised stator and rotor blades in a variety of blade series. The profile system, which is graduated according to chord length and stagger angle, is optimally coordiͭnated with regard to aerodynamic and strength factors. The complete blade family allows a turbine to be configured so that over all possible operating speed ranges blade vibration resonance is excluded.
All guide vanes and rotor blades are manufactured from corrosion-resistant chromium steels.
The blades used in these sections have a drop-shaped reaction profile with a relatively large radius on the leading edge. This makes the profil insensitive to variations in angle of incidence over a wide operating range and ensures good profile efficiency, even in the part-load and overload range.
The milled shrouds of the rotor blades reduce losses at the blade tip, thereby increasing efficiency. The shroud gap is sealed against the guide vane carrier by labyrinth seals. T-root, double T-root or pinned root fixings are used to attach the rotor blades, depending upon the mechanical load.
In the low pressure section, above a certain ratio of blade length to hub diameter, the rotor blades have twisted profiles.
These blades are designed as freeͭstanding, tapered blades with or without damping wires. The modular system includes T-root, double T-root and pinned root attachment options for the low-pressure blades. Surface hardening is also available, depending upon the application.
27 Blade family
25 Low-pressure blading
26 Intermediate-pressure blading
A single impulse stage or a Curtis wheel is used to control the turbine. The rotor blades are milled complete with integral shrouds from a single piece and in the area of the shrouds laterally caulked damping wires are inserted for optimum vibration damping. The radial gap betͭween the rotor blade shrouds and the guide vane carrier is sealed by means of labyrinth sealings strips to minimise losses.
On single impulse control stages the blades are attached to the rotor by a pinned root, whereas for Curtis wheel control stages double T-roots are used.
28 Control stage
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