2. Tubo-annu1ar
3. Annu1ar
Figure 10-12a. Top view of a large side combustor with special tiles (Courtesy.rown .overiTurbomachinery， Inc )
Figure 10-12b. Special tiles for a large side combustor (Courtesy.rown .overiTurbomachinery， Inc )
Figure 10-1.. Tubo-annular or can-annular combustor for a heavy-duty gas turbine (Courtesyof General Electric Company )
Tubu1ar or sing1e-can designs are preferred by many European industria1 gas turbine designers. These 1arge sing1e combustors offer the advantage of simp1icity of design and 1ong 1ife because of 1ow heat-re1ease rates. These com-bustors are sometimes very 1arge. They can range in size from sma11 units ofabout 6 inches (15.24 cm) in diameter and a 1 ft (0.3 m) high to combustors， which are over 10feet (3 m) indiameter and 30-40 feet(3-12 m)high. These1arge combustors use specia1 ti1es as 1iners. Any 1iner damage can be easi1y corrected by rep1acing the damaged ti1es. Figure 10-12 shows such a 1iner. The tubu1ar combustors can be designed as ..straight-through'' or ..reverse-f1ow designs.''Most 1arge sing1e-can combustors are of the reverse-f1ow design. ln this design， the air enters the turbine through the annu1us between the combustor can and the hot gas pipe as seen in Figure 10-13. The air then passes between the 1iner and the combustor can and enters the combustion region at various points of entry.About 10% of the air enters the combustion zone， about 30-40% of the air isused for coo1ing purposes， the rest is used in the di1ution zone. Reverse-f1ow designs are much shorter than the straight-through f1ow designs.
The tubu1ar， orsing1e-can， for 1arge units usua11y has more than one nozz1e. ln many cases a ring of nozz1es is p1aced in the primary zone area. The radia1 and circumferentia1 distribution of the temperature to the turbine nozz1es is not as even as in tubo-annu1ar combustors.
Tubo-annu1ar combustors are the most common type of combustors used in gas turbines. The industria1 gas turbines designed by ..S. companies use the tubo-annu1ar or can-annu1ar type seen in Figure 10-14. The advantage to these types of combustors are the ease of maintenance. They a1so have a better temperature distribution than the side sing1e-can combustor and can be of the straight-through or reverse-f1ow design. As with the sing1e-cancombustor， most of these combustors are of the reverse-f1ow design in indus-tria1 turbines.
ln most aircraft engines the tubo-annu1ar combustors are of the straight-through f1ow type seen in Figure 10-15. The straight-through f1ow type
Figure 10-1.. Aircraft-type annular combustion chamber (( Rolls-Royce Limited )
tubo-annu1ar combustor requires a much sma11er fronta1 area than the reverse-f1ow type tubo-annu1ar combustor. The tubo-annu1ar combustor a1so requires more coo1ing air f1ow than a sing1e or annu1ar combustor because the surface area of the tubo-annu1ar combustor is much greater. The amount of coo1ing air is not much of a prob1em in turbines using high-Btugas， but for 1ow-Btu gas turbines， the amount of air required in theprimary zone can be as high as 35% of the tota1 air needed， thus reducing the amount of air avai1ab1e for coo1ing purposes.
Higher temperatures a1so require morecoo1ingand， as temperaturesincrease， the sing1e can or annu1ar combustor design becomes more attrac-tive. The tubo-annu1ar combustor has a more even combustion because eachcan has its own nozz1e and a sma11er combustion zone， resu1ting in a much more even f1ow. Deve1opment of a tubo-annu1ar combustor is usua11y 1essexpensive， since on1y one can needs to be tested instead of an entire unit as inan annu1ar or sing1e-can combustor. Therefore， the fue1 and air requirements can be as 1ow as 8-10% of the tota1 requirements. 中國航空網 www.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：燃氣渦輪工程手冊 Gas Turbine Engineering Handbook 2(46)
