Publications

The Effect of Isentropic Exponent on Transonic Turbine Performance

The isentropic exponent is one of the most important properties affecting gas dynamics. Nonetheless, its effect on turbine performance is not well known. This paper discusses a series of experimental and computational studies to determine the effect of isentropic exponent on the flow field within a turbine vane. Experiments are performed using a newly modified transient wind tunnel that enables annular cascade testing with a wide range of working fluids and operating conditions. For the present study, tests are undertaken using air, CO2, R134a, and argon, giving a range of isentropic exponent from 1.08 to 1.67. Measurements include detailed wall static pressures that are compared with computational simulations. Our results show that over the range of isentropic exponents tested here, the loss can vary between 20% and 35%, depending on vane exit Mach number.

Authors:

David Baumgartner, John J. Otter, Andrew P. S. Wheeler

Publication:

Journal of Turbomachinery

DOI:

DOI: 10.1115/1.4046528

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A study of trailing-edge losses in organic Rankine cycle turbines

In this paper, vane trailing-edge losses which occur in organic rankine cycle (ORC) turbines are investigated. Experiments are performed to study the influence of dense gas effects on trailing-edge loss in supersonic flows using a novel Ludwieg tube facility for the study of dense-gas flows. The data is also used to validate a computational fluid dynamics (CFD) flow solver. The computational simulations are then used to determine the contributions to loss from shocks and viscous effects which occur at the vane trailing edge. The results show that dense gas effects play a vital role in the structure of the trailing-edge flow, and control the extent of shock and viscous losses

Authors:

Francisco J. Durá Galiana, Andrew P.S. Wheeler and Jonathan Ong

DOI:

10.1115/1.4033473

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The Role of Dense Gas Dynamics on Organic Rankine Cycle Turbine Performance

In this paper, we investigate the real gas flows which occur within organic Rankine cycle (ORC) turbines. A new method for the design of nozzles operating with dense gases is discussed, and applied to the case of a high pressure ratio turbine vane. A Navier-Stokes method, which uses equations of states for a variety of working fluids typical of ORC turbines, is then applied to the turbine vanes to determine the vane performance. The results suggest that the choice of working fluid has a significant influence on the turbine efficiency.

Authors:

Andrew P. S. Wheeler, Jonathan Ong

Publication:

Journal of Engineering for Gas Turbines and Power

DOI:

10.1115/1.4024963

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