[article]
| Titre : |
Influence of film cooling unsteadiness on turbine blade leading edge heat flux |
| Type de document : |
texte imprimé |
| Auteurs : |
James L. Rutledge, Auteur ; Paul I. King, Auteur ; Richard B. Diver, Auteur |
| Année de publication : |
2012 |
| Article en page(s) : |
10 p. |
| Note générale : |
Génie mécanique |
| Langues : |
Anglais (eng) |
| Mots-clés : |
Hot gas path Turbine engine Heat transfer |
| Index. décimale : |
620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux |
| Résumé : |
Film cooling in the hot gas path of a gas turbine engine can protect components from the high temperature main flow, but it generally increases the heat transfer coefficient h partially offsetting the benefits in reduced adiabatic wall temperature. We are thus interested in adiabatic effectiveness eta and h which are combined in a formulation called net heat flux reduction (NHFR). Unsteadiness in coolant flow may arise due to inherent unsteadiness in the external flow or be intentionally introduced for flow control. In previous work it has been suggested that pulsed cooling flow may, in fact, offer benefits over steady blowing in either improving NHFR or reducing the mass flow requirements for matched NHFR. In this paper we examine this hypothesis for a range of steady and pulsed blowing conditions. We use a new experimental technique to analyze unsteady film cooling on a semicircular cylinder simulating the leading edge of a turbine blade. The average NHFR with pulsed and steady film cooling is measured and compared for a single coolant hole located 21.5° downstream from the leading edge stagnation line, angled 20° to the surface and 90° to the streamwise direction. We show that for moderate blowing ratios at blade passing frequencies, steady film flow yields better NHFR. At higher coolant flow rates beyond the optimum steady blowing ratio, however, pulsed film cooling can be advantageous. We present and demonstrate a prediction technique for unsteady blowing at frequencies similar to the blade passing frequency that only requires the knowledge of steady flow behavior. With this important result, it is possible to predict when pulsing would be beneficial or detrimental. |
| DEWEY : |
620.1 |
| ISSN : |
0742-4795 |
| En ligne : |
http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000007 [...] |
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 7 (Juillet 2012) . - 10 p.
[article] Influence of film cooling unsteadiness on turbine blade leading edge heat flux [texte imprimé] / James L. Rutledge, Auteur ; Paul I. King, Auteur ; Richard B. Diver, Auteur . - 2012 . - 10 p. Génie mécanique Langues : Anglais ( eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 7 (Juillet 2012) . - 10 p.
| Mots-clés : |
Hot gas path Turbine engine Heat transfer |
| Index. décimale : |
620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux |
| Résumé : |
Film cooling in the hot gas path of a gas turbine engine can protect components from the high temperature main flow, but it generally increases the heat transfer coefficient h partially offsetting the benefits in reduced adiabatic wall temperature. We are thus interested in adiabatic effectiveness eta and h which are combined in a formulation called net heat flux reduction (NHFR). Unsteadiness in coolant flow may arise due to inherent unsteadiness in the external flow or be intentionally introduced for flow control. In previous work it has been suggested that pulsed cooling flow may, in fact, offer benefits over steady blowing in either improving NHFR or reducing the mass flow requirements for matched NHFR. In this paper we examine this hypothesis for a range of steady and pulsed blowing conditions. We use a new experimental technique to analyze unsteady film cooling on a semicircular cylinder simulating the leading edge of a turbine blade. The average NHFR with pulsed and steady film cooling is measured and compared for a single coolant hole located 21.5° downstream from the leading edge stagnation line, angled 20° to the surface and 90° to the streamwise direction. We show that for moderate blowing ratios at blade passing frequencies, steady film flow yields better NHFR. At higher coolant flow rates beyond the optimum steady blowing ratio, however, pulsed film cooling can be advantageous. We present and demonstrate a prediction technique for unsteady blowing at frequencies similar to the blade passing frequency that only requires the knowledge of steady flow behavior. With this important result, it is possible to predict when pulsing would be beneficial or detrimental. |
| DEWEY : |
620.1 |
| ISSN : |
0742-4795 |
| En ligne : |
http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000007 [...] |
|
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