Aerothermodynamics and operation of turbine system under unsteady pulsating flow
Name
920688212-MIT.pdf
Description
Full printable version
Size
18.36 MB
Format
Adobe PDF
Checksum (MD5)
7fa0b29f719935247980fcb5e5bd6061
Author(s)
Lee, Jinwook, Ph. D. Massachusetts Institute of Technology
Advisor(s)
Choon S. Tan and Borislav T. Sirakov.
Date Issued
2015
Publisher
Massachusetts Institute of Technology
Abstract
An assessment of a turbine system operating under highly pulsating flow environment typically found in vehicular turbochargers is made to: identify the key operating parameters, enable the formulation of a reduced order model, delineate the sources of loss and suggest strategies for performance improvement. The turbine system consists of a scroll-volute followed by a turbine wheel and then a diffuser. The assessment includes calculating unsteady three-dimensional flow in the turbine system followed by in-depth interrogation complemented with flow modeling. The key findings are (1) The flow mechanisms behind the turbine wheel performance, the diffuser loss and the wastegate port loss appear locally quasi-steady such that we can characterize the performance of the components based on a series of steady calculations subjected to varying inlet conditions reflecting the inlet flow pulsation; (2) the operation of scroll-volute and the diffuser pressure recovery can be adequately determined using a quasi-one-dimensional unsteady flow model; (3) A significant fraction of the loss that is not from skin frictions occurs downstream of turbine wheel exit (18%pts out of 34%pts in Peak Torque and 20%pts out of 56%pts in Turbo Initial Transient based on cycle loss debit); (4) The condition of maximum power extraction on unsteady pulsating environment can be approximated with a simple modeling of volute storage effect. A physically consistent definition of ideal power that elucidates the role of unsteadiness in an unsteady turbine system is derived; it informs one on what the extractable power is compared to what it could be for an ideal system. Finally the findings are used to define the required attributes of methodology for estimating efficiency with a specified uncertainty bandwidth.
Description
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 133-135).
Subjects
Aeronautics and Astronautics.
MIT Department
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics
Terms of Use
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
Persistent DSpace Link
