Detailed experimental investigation has been conducted to provide a detailed insight
into the heat transfer and aerodynamic behavior of a separation zone that is generated as a
result of boundary layer development along the suction surface of a highly loaded low
pressure turbine (LPT) blade. The research experimentally investigates the individual and
combined effects of periodic unsteady wake flows and freestream turbulence intensity (Tu)
on heat transfer and aerodynamic behavior of the separation zone. Heat transfer experiments
were carried out at Reynolds number of 110,000, 150,000, and 250,00 based on the suction
surface length and the cascade exit velocity. Aerodynamic experiments were performed at
Re = 110,000 and 150,000. For the above Re-numbers, the experimental matrix includes
Tus of 1.9%, 3.0%, 8.0%,13.0% and three different unsteady wake frequencies with the
steady inlet flow as the reference configuration. Detailed heat transfer and boundary layer
measurements are performed with particular attention paid to the heat transfer and
aerodynamic behavior of the separation zone at different Tus at steady and periodic
unsteady flow conditions. The objectives of the research are (a) to quantify the effect of Tu
on the aero-thermal behavior of the separation bubble at steady inlet flow condition, (b) to
investigate the combined effects of Tu and the unsteady wake flow on the aero-thermal
behavior of the separation bubble, and (c) to provide a complete set of heat transfer and
aerodynamic data for numerical simulation that incorporates Navier-Stokes and energy
equations. The analysis of the experimental data reveals details of boundary layer separation
dynamics which is essential for understanding the physics of the separation phenomenon
under periodic unsteady wake flow and different Reynolds number and Tu. To provide a
complete picture of the transition process and separation dynamics, extensive intermittency
analysis was conducted. Ensemble averaged maximum and minimum intermittency
functions were determined leading to the relative intermittency function. In addition, the
detailed intermittency analysis reveals that the relative intermittency factor follows a
Gaussian distribution confirming the universal character of the relative intermittency
function.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1150 |
| Date | 15 May 2009 |
| Creators | Ozturk, Burak |
| Contributors | Schobeiri, T. M. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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