International Journal of Gas Turbine, Propulsion and Power Systems
Online ISSN : 1882-5079
Volume 12, Issue 1
Displaying 1-2 of 2 articles from this issue
  • Pingting Chen, Xueying Li, Hongde Jiang
    2021 Volume 12 Issue 1 Pages 1-9
    Published: 2021
    Released on J-STAGE: February 20, 2021
    Non-axisymmetric contoured endwall can reduce aerodynamic loss in axial turbine if the endwall shape is well designed. Meanwhile, contouring of the endwall can change the value of the total heat flux through the endwall, mainly by changing the distribution of heat transfer coefficient and the endwall area. In this study, several optimized non-axisymmetric contoured endwall shapes are found in an annular cascade passage by a multi-objective optimization process to achieve both improved aerodynamic performance in the passage and more beneficial heat transfer characteristics on the endwall. The optimized contoured endwall designs were found and they are all with sunken area in the middle of the passage and risen area in the aft part of the passage near the suction side. In addition, the case with better heat transfer performance features higher area-averaged heat transfer coefficient but with smaller total endwall area.
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  • Stefan T¨uchler, Colin D. Copeland
    2021 Volume 12 Issue 1 Pages 10-24
    Published: 2021
    Released on J-STAGE: February 20, 2021
    In this paper, an alternative micro-gas turbine is proposed, where the traditional compressor-turbine arrangement is replaced by an axial, throughflow wave rotor. The investigated wave rotor features symmetrically cambered wall profiles and angled port arrangement for shaft power extraction and uses shock and rarefaction waves for pressure exchange and to achieve gas compression and expansion within a single device. A validated quasi-one-dimensional model that solves the laminar Navier-Stokes equations using a two-step Richtmyer scheme with minmod flux limiter is employed to characterise and examine microgas turbine behaviour. The model accounts for wall heat transfer, flow leakage, wall friction and inviscid blade forces. In addition, modified boundary conditions consider finite passage opening effects and a simple steady-flow combustor model is defined that links the high pressure in- and outlet ports. The model is used to conduct a parametric study to investigate the effects of leakage gap, heat release rate, exhaust backpressure, as well as profile camber on gas turbine performance with a focus on generated combustor compression and expansion efficiency, shaft power and system efficiency. The implications of combustor pressure loss as well as effects of a potential recuperator are discussed as well. The results identify axial leakage and combustor pressure loss as primary drivers for enhanced performance. Finally, the results reinforce the capacity of wave rotors to compress and expand gas efficiently, while thermal efficiency remains below 10 percent.
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