Aeros

A. K. Rappe, C. J. Casewit, Molecular Mechanics aero.. s Chemistry University Science Books, Sausalito (1997). 

Heating Facihty and El Aero Heating Facihty, NASA/Ames. Numbers on the curves indicate stagnation pressure in MPa — balhstic entry -, lifting... 

H. Shaw, C. D. Kalfadehs, and C. E. Jahnig, Evaluation of Methods to Produce Aviation Turbine Fuels From Synthetic Crude Oils-Phase I, Technical Report AFAPL-TR-75-10, Vol. 1, Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio, Mar. 1975. 

Laurion, U.S. Pat. No. 3,847,443, discloses an oma-mental wheel element which is designed to fit between the spokes, inside a wheel. Strazis, U.S. Pat. No. 4,682,821, discloses a semi-rigid, tension attached bicycle wheel cover assembly intended to improve the aero-dynamic efficiency of bicycle wheels. Monte, U.S. Pat. 

Most gas-fired, heavy-duty gas turbines installed as of 1996 operate at gas pressures between 1.2 and 1.7 MPa (180—250 psig). However, aero derivative gas turbines and newer heavy-duty units can have such high air-inlet compression ratios as to require booster compressors to raise gas inlet pressures, in some cases as high as 5.2 MPa (750 psig). 

Cmde calcium cyanide [592-01-8] about 48 to 50 eq % sodium cyanide, is the only commercially important alkaline-earth metal cyanide, and output toimage has been greatiy reduced. This product, commonly called black cyanide, is marketed in flake form as a powder or as cast blocks under the trademarks Aero and Cyanogas of the American Cyanamid Co. 

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). 

The other mechanism appears in scrubbers. When water vapor diffuses from a gas stream to a cold surface and condenses, there is a net hydrodynamic flow of the noncondensable gas directed toward the surface. This flow, termed the Stefan flow, carries aerosol particles to the condensing surface (Goldsmith and May, in Davies, Aero.sol Science, Academic, New York, 1966) and can substantially improve the performance of a scrubber. However, there is a corresponding Stefan flow directed away from a surface at which water is evaporating, and this will tend to repel aerosol particles from the surface. 

The Aero pulverizer (Foster Wheeler Coij).) is used for coal, pitch, and coke, blowing the ground material direcdly into the furnace. The housing is divided into two or three short cylindrical pulverizing chambers. 

Now a second example, taking us from low technology to the advanced materials design involved in the turbofan aero-engines which power large planes. Air is propelled... 

These requirements severely limit our choice of creep-resistant materials. For example, ceramics, with their high softening temperatures and low densities, are ruled out for aero-engines because they are far too brittle (they are under evaluation for use in land-based turbines, where the risks and consequences of sudden failure are less severe - see below). Cermets offer no great advantage because their metallic matrices soften at much too low a temperature. The materials which best fill present needs are the nickel-based super-alloys. 

Slides Turbofan aero-engine super-alloy turbine blades, showing cooling ports [3] super-alloy microstructures [4] DS eutectic microstructures [3, 5] ceramic turbine blades. 

Nickel and its alloys form another important class of non-ferrous metals (Table 1.3). The superb creep resistance of the nickel-based superalloys is a key factor in designing the modern gas-turbine aero-engine. But nickel alloys even appear in a model steam engine. The flat plates in the firebox must be stayed together to resist the internal steam pressure (see Fig. 1.3). Some model-builders make these stays from pieces of monel rod because it is much stronger than copper, takes threads much better and is very corrosion resistant. 

Compressor performance can be represented in various ways. The commonly accepted practice is to plot the speed lines as a function of the pressure delivered and the flow. Figure 3-9 is a performance map for a centrifugal compressor. The constant speed lines shown in Figure 3-9 are constant aero-dynamic speed lines, not constant mechanical speed lines. 

Mechanical Drives. Mechanical drive gas turbines are widely used to drive pumps and compressors. Their application is widely used by offshore and petrochemical industrial complexes. These turbines must be operated at various speeds and thus usually have a gasifier section and a power section. These units in most cases are aero-derivative turbines, turbines, which were originally designed for aircraft application. There are some smaller frame type units, which have been converted to mechanical drive units with a gasifier and power turbine. 

Medium-sized gas turbines between 5-50 MW are a combination of aero-derivative and frame type turbines. These gas turbines have axial flow compressors and axial flow turbines. 

The location of the plant is the principal determination of the type of plant best configured to meet its needs. Aero-derivatives are used on offshore platforms. Industrial turbines are mostly used in petrochemical applications, and the frame type units are used for large power production. 

Plant Type. The determination to have an aero-derivative type gas turbine or a frame-type gas turbine is the plant location. In most cases if the plant is located off-shore on a platform then an aero-derivative plant is required. On most on-shore applications, if the size of the plant exceeds 100 MW then the frame type is best suited for the gas turbine. In smaller plants between 2-20 MW, the industrial type small turbines best suit the application, and in plants between 20-100 MW, both aero-derivative or frame types can apply. Aero-derivatives have lower maintenance and have high heat-recovery capabilities. In many cases, the type of fuel and service facilities may be the determination. Natural gas or diesel no. 2 would be suited for aero-derivative gas turbines, but heavy fuels would require a frame type gas turbine. 

Gas turbine size is important in the cost of the plant. The larger the gas turbine the less the initial cost per kW. The aero-derivative turbines have traditionally been higher in efficiency however, the new frame type turbines have been closing the gap in efficiency. Figure 4-3 shows typical gas... 

Figure 4-4. Installed cost and efficiency of aero-derIvatIve type turbines.

Aero-derivative gas turbines eannot operate on heavy fuels, thus if heavy fuels was a eriteria then the frame type turbines would have to be used. With heavy fuels, the power delivered would be redueed after about a weeks of operation by about 10%. On-line turbine wash is reeommended for turbines with high vanadium eontent in their fuel, sinee to counteract vanadium magnesium salts have to be added. These salts cause the vanadium when combusted in the turbine to be turned to ashes. This ash settles on the turbine blades and reduces the cross sectional area, thus reducing the turbine power. 

Ball/race frequencies in antifriction bearings usually used in aero-... 

This phenomenon is caused by self-excitation of the blade and is aero-elastic. It must be distinguished from classic flutter, since classic flutter is a coupled torsional-flexural vibration that occurs when the freestream velocity over a wing or airfoil section reaches a certain critical velocity. Stall flutter, on the other hand, is a phenomenon that occurs due to the stalling of the flow around a blade. 

Holmquist, L.O., and Rannie, W.D., An Approximate Method of Calculating Three-Dimensional Flow in Axial Turbomachines (Paper) Meeting Inst. Aero. Sci., New York, January 24-28, 1955. 

Clarke, J.S., and Lardge, H.E., The Performance and Reliability of Aero-Gas Turbine Combustion Chambers, ASME 58-GTO-13, 1958. 

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