TY - JOUR

T1 - Interaction between Struts and Swirl Flow in Gas Turbine Exhaust Diffusers

AU - Pietrasch, Roman Z.

AU - Seume, Joerg R.

N1 - Funding information: The research on which this paper is based was sponsored by the DFG (Deutsche Forschungsgesellschaft') and carried out at the Turbomachinery Laboratory, University of Hannover, Germany. The authors would like to thank Sebastian Kanzer and Bastian Schreyer for their helpfully and frequently input and guidance. Special thanks to Simon Kneser and Kathrin Henke for their effort in design, programming, and measuring. Additionally, thanks to Benno Fuhrmann for his perfectly manufacturing of the turnable hub

PY - 2005/12

Y1 - 2005/12

N2 - The increasing use of gas turbines in combined cycle power plants together with the high amount of kinetic energy in modern gas turbine exhaust flows focuses attention on the design of gas turbine diffusers as the connecting part between the Brayton/Joule and the Rankine parts of the combined cycle. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. The test rig consists of a radial type, variable swirl generator which provides the exhaust flow corresponding to different gas turbine operating conditions. Static pressure measurements are carried out along the outer diffuser walls and along the hub of the annular part and along the centerline of the conical diffuser. Velocity distributions at several axial positions in the annular and conical diffuser have been measured using a Laser Doppler Velocimeter (LDV). Pressure recovery coefficients and velocity profiles are depicted as a function of diffuser length for several combinations of swirl strength, tip flow and strut geometries. The diffuser without struts achieved a higher pressure recovery than the diffuser with struts at all swirl angle settings. The diffuser with cylindrical struts achieved a higher pressure recovery than the diffuser with profiled struts at all swirl angle settings. Inlet flows with swirl angles over 18° affected the pressure recovery negatively for all strut configurations.

AB - The increasing use of gas turbines in combined cycle power plants together with the high amount of kinetic energy in modern gas turbine exhaust flows focuses attention on the design of gas turbine diffusers as the connecting part between the Brayton/Joule and the Rankine parts of the combined cycle. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. The test rig consists of a radial type, variable swirl generator which provides the exhaust flow corresponding to different gas turbine operating conditions. Static pressure measurements are carried out along the outer diffuser walls and along the hub of the annular part and along the centerline of the conical diffuser. Velocity distributions at several axial positions in the annular and conical diffuser have been measured using a Laser Doppler Velocimeter (LDV). Pressure recovery coefficients and velocity profiles are depicted as a function of diffuser length for several combinations of swirl strength, tip flow and strut geometries. The diffuser without struts achieved a higher pressure recovery than the diffuser with struts at all swirl angle settings. The diffuser with cylindrical struts achieved a higher pressure recovery than the diffuser with profiled struts at all swirl angle settings. Inlet flows with swirl angles over 18° affected the pressure recovery negatively for all strut configurations.

KW - Gas turbine exhaust diffuser

KW - Pressure recovery coefficient

KW - Struts

KW - Swirl

UR - http://www.scopus.com/inward/record.url?scp=30044435029&partnerID=8YFLogxK

U2 - 10.1007/s11630-005-0051-x

DO - 10.1007/s11630-005-0051-x

M3 - Article

AN - SCOPUS:30044435029

VL - 14

SP - 314

EP - 320

JO - Journal of thermal science

JF - Journal of thermal science

SN - 1003-2169

IS - 4

ER -