Bio-Inspired Design of a Turbine Stage
Abstract
To reduce fuel burn, aircraft manufacturers and NASA are exploring concepts to maximize the thermal and propulsive efficiency, one concept is the hybrid turbo-electric powertrain. In these novel architectures, coupling an electrical generator one may encounter turbine incidence problems. There is also a demand for the gas generator to be compact to achieve weight savings which means the turbine will need to be both highly loaded and efficient. In nature, millions of years of evolution has produced designs that reduce drag over a wide range incidence angles. This dissertation presents a strategy that incorporates nature and bio-inspired shapes to redesign turbine airfoils and stator-rotor rim seal cavity. A differential evolution optimizer was used to fulfill the objectives of the thesis. The first objective consists of the development of tools to optimize the turbine velocity triangles and then the 3D shape using 75 parameters. Design trends that minimize loss in the stator and rotor were discussed. The second objective expands on the first by incorporating wavy structures at the leading and trailing edges as well as the suction side mimicking design features of seal whiskers and tubercles of a whale. The airfoils were optimized to maximize the efficiency of a highly loaded high-pressure turbine at positive incidence. The last objective addressed the design of the cavity to reduce cooling massflow and protect the turbine platform. A novel strategy was proposed to assess and optimize the shape of the cavity. In an attempt to simply the problem and identify the main physical phenomena, a slice of the flow was examined by considering a purely a 2D case in the relative frame of reference. This simplification enabled the cavity to be optimized in 2D using a geometry inspired by the meandering of rivers. The optimization produced designs that reduce the heat flux in the rear rotor platform and are less sensitive towards variations in gap and cavity total pressure. The methodology was demonstrated in 3D rotating cavity and later in a full turbine stage configuration. The strategy and design tools developed in this dissertation seek to provide understanding of the effects of bio-inspired shapes on turbine blades and lay the foundation for future experimental research into cavity flows.
Degree
Ph.D.
Advisors
Paniagua, Purdue University.
Subject Area
Design|Fluid mechanics|Mathematics|Mechanics
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