Details
| Original language | English |
|---|---|
| Pages (from-to) | 42-49 |
| Number of pages | 8 |
| Journal | Journal of thermal science |
| Volume | 17 |
| Issue number | 1 |
| Publication status | Published - 6 Mar 2008 |
Abstract
Highly efficient turbine exhaust diffuser cannot be designed without taking into account the unsteady interactions with the last rotating row of the turbine. Former investigations described in the literature show a very high potential compared to that of other parts of turbomachines for improving the diffuser. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. To investigate the influence of rotating wakes, measurements without a spoke wheel as well as measurements with a variable-speed rotating cylindrical spoke wheel with 2 mm-or 10 mm-spokes simulating turbine rotor wakes were made. Miniaturized 3-hole pneumatic probes as well as a 2D-Laser-Doppler-Velocimeter (LDV) were used to investigate velocity profiles. 122 static pressure tapings were used to measure several axial and circumferential static pressure distributions. Without a spoke-wheel the annular diffuser separates at the shroud for all swirl configurations. For the measurements with the 2 mm spoke wheel, the separating diffuser was unstable while keeping the test rig operating parameters constant. For a non-rotating 10 mm spoke wheel and at rotational speeds less than 1,000 rpm, the annular diffuser separated at the shroud. In-creasing the rotational speed of the 10mm spoke wheel, flow did not separate at the shroud and much higher pressure recovery than without spoke wheel has achieved.
Keywords
- LDV, Rotating wakes, Separation, Turbine exhaust diffuser
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Condensed Matter Physics
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In: Journal of thermal science, Vol. 17, No. 1, 06.03.2008, p. 42-49.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Influence of rotating wakes on separation in turbine exhaust diffusers
AU - Sieker, Olaf
AU - Seume, Joerg R.
N1 - Funding information: The research, on which this paper is based, is sponsored by German Ministry of Economics and Technology under the AG Turbo’s COOREFF-T program whose support is greatfully acknowledged. The work was carried out at the Institute of Turbomachinery and Fluid-Dynamics, Leibniz University Hannover/Germany. The authors would like to thank all colleagues for their input and guidance. Special thanks to Matthias Winter for helping to conduct the experiments.
PY - 2008/3/6
Y1 - 2008/3/6
N2 - Highly efficient turbine exhaust diffuser cannot be designed without taking into account the unsteady interactions with the last rotating row of the turbine. Former investigations described in the literature show a very high potential compared to that of other parts of turbomachines for improving the diffuser. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. To investigate the influence of rotating wakes, measurements without a spoke wheel as well as measurements with a variable-speed rotating cylindrical spoke wheel with 2 mm-or 10 mm-spokes simulating turbine rotor wakes were made. Miniaturized 3-hole pneumatic probes as well as a 2D-Laser-Doppler-Velocimeter (LDV) were used to investigate velocity profiles. 122 static pressure tapings were used to measure several axial and circumferential static pressure distributions. Without a spoke-wheel the annular diffuser separates at the shroud for all swirl configurations. For the measurements with the 2 mm spoke wheel, the separating diffuser was unstable while keeping the test rig operating parameters constant. For a non-rotating 10 mm spoke wheel and at rotational speeds less than 1,000 rpm, the annular diffuser separated at the shroud. In-creasing the rotational speed of the 10mm spoke wheel, flow did not separate at the shroud and much higher pressure recovery than without spoke wheel has achieved.
AB - Highly efficient turbine exhaust diffuser cannot be designed without taking into account the unsteady interactions with the last rotating row of the turbine. Former investigations described in the literature show a very high potential compared to that of other parts of turbomachines for improving the diffuser. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. To investigate the influence of rotating wakes, measurements without a spoke wheel as well as measurements with a variable-speed rotating cylindrical spoke wheel with 2 mm-or 10 mm-spokes simulating turbine rotor wakes were made. Miniaturized 3-hole pneumatic probes as well as a 2D-Laser-Doppler-Velocimeter (LDV) were used to investigate velocity profiles. 122 static pressure tapings were used to measure several axial and circumferential static pressure distributions. Without a spoke-wheel the annular diffuser separates at the shroud for all swirl configurations. For the measurements with the 2 mm spoke wheel, the separating diffuser was unstable while keeping the test rig operating parameters constant. For a non-rotating 10 mm spoke wheel and at rotational speeds less than 1,000 rpm, the annular diffuser separated at the shroud. In-creasing the rotational speed of the 10mm spoke wheel, flow did not separate at the shroud and much higher pressure recovery than without spoke wheel has achieved.
KW - LDV
KW - Rotating wakes
KW - Separation
KW - Turbine exhaust diffuser
UR - http://www.scopus.com/inward/record.url?scp=40549085026&partnerID=8YFLogxK
U2 - 10.1007/s11630-008-0042-9
DO - 10.1007/s11630-008-0042-9
M3 - Article
AN - SCOPUS:40549085026
VL - 17
SP - 42
EP - 49
JO - Journal of thermal science
JF - Journal of thermal science
SN - 1003-2169
IS - 1
ER -