Compressors, blades

One candidate is a titanium alioy that is reinforced with iarge diameter SiC/C filaments (see Chapter 4) and is fabricated by superplastic forming/ diffusion bonding. This MMC is suited to the fabrication of bladed compressor rings, shafts, ducks, fan components or structural rods for jet engines. Their use for parts submitted to still higher temperatures is limited by tiber/matrix reaction and environmental considerations. Titanium aluminide TisAI (or y-TiAl) matrices could permit an increase in the service temperature of the composites. 

Compressor rotor assembly Stator blades, rotor blades Compressor case assembly Air inlet filter assembly Bearings and seals Compressor diffuser assembly... 

Laser welding Extremely accurate and much less heat intensive than conventional repair, laser welding is particularly useful for turbine blades, compressor blade leading edges, and other sensitive components. 

Full-Form Shaping. The third appHcation of ECM, hill-form shaping, uti1i2es a constant gap across the entire workpiece, and a constant feed rate in order to produce the type of shape used for the production of compressor and turbine blades. In this procedure, current densities as high as 100 A/cm ate used, and the current density remains high across the entire face of the workpiece. 

Most rotating equipment includes electric motors or steam dryers that generate noise at a constant frequency. Air cooler fans are a source of noise that can be reduced by lowering the fan speed and increasing the number of blades. Pump motor noise can be reduced by including a shroud or fan cover that is accurately lined. Centrifugal compressor noise reduction can be achieved by blade design and the use of compressor pulsation noise reduction, silencers, and vibration isolation. 

In some cases, blade-type rotary compressors are used in low temperature appHcations as high volume, low stage, or booster compressor (Fig. 9). These booster compressors are appHed at suction conditions varying from —87 to —20°C with compression ratios of 7 1 using CFC-12, HCFC-22, or ammonia. 

PMR-15—carbon fiber composites include jet-engine cowlings, ducts, compressor blades, and flaps and fairings (24,38). 

The axial flow compressors in aero gas turbines are heavily loaded. The aspecl ratio of the blades, especially the first few stages, can be as high as 4.0, and the effecl of streamhne curvature is substantial. The streamline configuration is a function of the annular passage area, the camber and thickness distribution of the blade, and the flow angles at the inlet and outlet of the blades. The shafts on these units are supported on antifriction bearings (roller or ball bearings). 

Droplet breakup via impingement appears to follow a similar relationship, but much less data is available. This type of breakup can result from impingement on equipment walls or compressor blades. In general, there is less tendency to shatter on wetted surfaces. 

Turbine-Blade Cooling The turbine inlet temperatures of gas turbines have increased considerably over the past years and will continue to do so. This trend has been made possible by advancement in materials and technology, and the use of advanced turbine bladecooling techniques. The olade metal temperature must be kept below 1400° F (760° C) to avoid hot corrosion problems. To achieve this cooling air is bled from the compressor and is directed to the stator, the rotor, and other parts of the turbine rotor and casing to provide adequate cooling. The effect of the coolant on the aerodynamic, and thermodynamics depends on the type of cooling involved, the temperature of the coolant compared to the mainstream temperature, the location and direction of coolant injection, and the amount of coolant. 

Figure 4-10. Compressor train for dual-pressure installation consisting of an axial flow air compressor with adjustable stator blades and a radial flow nitrous gas compressor and expander. Mass flow air = 139,000 Nm /h, nitrous gases = 122,500 Nm /h Pressure air = 0.82/4.75 bar, nitrous gases = 4.38/10.8 bar Power input total = 16,840 kW Power recovery by expander = 10,950 kW.

Figure 4-15. Axial compressor with fixed stator blades, double-casing design, and forged monoblock rotor. Particularly suitable for compressing nitrous gases. There are no dead spaces provoking buildup of ammonium nitrate salt.

Figure 4-16. Axial compressor with adjustable stator blades, either partially or on all stages. Double-casing design and forged monoblock rotor. This design offers a wide operating range especially in combination with speed control.

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