Experimental and theoretical investigations of heat transfer in closed gas-filled rotating annuli 2
- Technical Univ. of Aachen (Germany). Inst. of Steam and Gas Turbines
Increasing the thermal efficiency by higher turbine inlet temperatures is one of the most important aims in the area of gas turbine development. Because of the high temperatures, the turbine vanes and blades have to be cooled, and also knowledge of the mechanically and thermally stressed parts in the hottest zones of the rotor is of great interest. The present paper deals with investigations on a pure axially directed heat flux. An experimental setup was designed to realize a wide range of Ra numbers (2 {times} 10{sup 8} < Ra < 5 {times} 10{sup 10}) usually encountered in cavities of gas turbine rotors. Parallel to the experiments, numerical calculations have been conducted. The numerical results are compared with the experimental data. The numerical scheme is also used to account for the influence of Re on heat transfer without changing Ra. This influence could not be pointed out by experiments, because a variation of the Re-Ra characteristic of the employed annuli was not possible. It was found that the numerical and experimental data are in quite good agreement, with exception of high Ra, where the numerical scheme predicts higher heat transfer than the experiments show. One reason may be that in the experiments the inner and outer cylindrical walls were not really adiabatic, an assumption used in the numerical procedure. Moreover, the assumption of a two-dimensional flow pattern may become invalid for high Ra. The influence of three-dimensional effects was studied with the three-dimensional version of the numerical code. In contrast to the radial directed heat transfer, it was found that Nu is much smaller and depends strongly on Re, whereas the radial heat transfer is only weakly influenced by Re.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 194214
- Report Number(s):
- CONF-940626-; ISSN 0889-504X; TRN: IM9611%%55
- Journal Information:
- Journal of Turbomachinery, Vol. 118, Issue 1; Conference: 39. international gas turbine and aeroengine congress and exposition, The Hague (Netherlands), 13-16 Jun 1994; Other Information: PBD: Jan 1996
- Country of Publication:
- United States
- Language:
- English
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