<p>Pressure gain combustion is beneficial for engine cycle
efficiency, compactness, and less emissions. In this disseration, two classes
of fluid expansions systems were developed to harness power from the high-speed
flow delivered by the pressure gain combustor: a compact expansion system and
an efficiency expansion system. In addition, a new class of pressure probes for
expansion systems is developed.</p>
<p>A numerical methodology is carried out to design and
characterize these expansion devices and measurement systems via steady and
unsteady Reynolds Averaged Navier stokes simulations. Firstly, the compact
expansion system is achieved by developing a supersonic axial turbine. Performance
of the supersonic axial turbine exposed to fluctuations from a nozzle downstream
of a rotating detonation combustor is assessed with an increased level of
complexity, including time-resolved stator, time-resolved rotor, and
time-resolved turbine stage characterization. Power extraction, damping of
fluctuations, and loss budgeting are evaluated. Unsteady heat transfer
assessment is performed to investigate the convective heat flux distribution
and decomposition. A performance map is constructed to explore the operating
limit. Afterwards, the efficient expansion system is achieved by retrofitting an
existing subsonic axial turbine. Without redesigning turbine airfoils, the stator
endwall contour was modified to integrate the subsonic axial turbine to a
diffuser and a rotating detonation combustor. Performance of the retrofitted
subsonic axial turbine exposed to fluctuations form a diffuser is evaluated at
several frequencies, amplitudes and inlet Mach numbers, with an increased level
of model fidelity, including unsteady stator alone, unsteady turbine stage with
a reduced model, full unsteady turbine stage assessment. Turbine efficiency,
damping of oscillations, and loss budgeting are assessed. A multi-step
optimization strategy is utilized to enhance turbine efficiency by improving
the endwall contouring. A performance map is created to examine the operating
range. Finally, a new type of pressure probes was developed and angular
calibration was performed. A whisker-inspired design enabled the reduction of
the vortex shedding effect.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/11327942 |
| Date | 05 December 2019 |
| Creators | Zhe Liu (8088038) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Characterization_of_Axial_Turbines_for_Pressure_Gain_Combustion/11327942 |
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