<p>To increase overall
aircraft engine efficiency, the diameter of the high-pressure turbine is
reduced, leading to low aspect ratio airfoils. Secondary flow dominates in
these low aspect ratio turbines, and the small airfoil geometry inhibits
flush-mounted, full-spatial dynamic pressure measurements with pressure
transducers. Airfoil surface pressure measurements are vital to understanding
the inherently unsteady flow phenomena in turbines. Additionally, aerodynamic performance
data derived from high-resolution surface pressure measurements provide
invaluable data for validating computational fluid dynamics codes used for
prediction. Non-intrusive measurement techniques such as fast-responding
Pressure Sensitive Paint (PSP) offer a potential solution of a full-field optical
measurement of surface pressure fluctuation, with each camera pixel
representing a sensor. The porous binder
improves the dynamic response of PSP,
making it suitable for unsteady flow environments such as turbomachinery
applications. In this view, the overall objective of the current doctoral
research is to develop a lifetime PSP method using laser-based excitation for
surface pressure measurement on a new class of high-pressure turbines. </p>
<p>The overall research
goal was subdivided into three main strategies. (1) A pulse lifetime calibration
procedure of a porous polymer/ceramic binder PSP was developed in a
pressure-controlled chamber to assess the correlation between pressure and time-resolved
luminescent lifetime, pressure sensitivity, and signal-to-noise ratio. (2) The
lifetime technique was implemented for surface pressure measurements in a
linear test section to measure high spatial pressure gradients and resolve
unsteady flow features. A data reduction routine and an optimal binning bundle
of pixels were proposed for calibration analysis to reduce the overall pressure
uncertainty. Uncertainty quantification and sensitivity analysis were also
completed to determine the parameters with a substantial effect on the pressure
uncertainty. (3) The pulse lifetime method was demonstrated on a high-pressure
turbine vane suction surface at engine representative conditions. The surface pressure
data were corroborated with static pressure tappings and computational
simulations. This research effort provided new insights into time-resolved
luminescent lifetime PSP techniques. Steady and unsteady flow features from
surface pressure measurements were identified using a precise calibration
method. The lifetime pulse method was effective in a high-pressure turbine flow
field, paving the way for back-to-back PSP experiments with different turbine
geometries. </p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/17153381 |
| Date | 19 December 2021 |
| Creators | Papa Aye Nyansafo Aye-Addo (11811563) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/DEVELOPMENT_OF_A_LASER_LIFETIME_PRESSURE-SENSITIVE_PAINT_METHOD_FOR_TURBINE_ANALYSIS/17153381 |
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