An experimental/computational study of airflow in the combustor-diffuser system of a gas turbine for power generation

    Authors

    A. K. Agrawal; J. S. Kapat;T. T. Yang

    Comments

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    Abbreviated Journal Title

    J. Eng. Gas. Turbines Power-Trans. ASME

    Keywords

    FLOW; DUMP; Engineering, Mechanical

    Abstract

    This paper presents an experimental/computational study of cold flow in the combustor-diffuser system of industrial gas turbines employing can-annular combustors and impingement-cooled transition pieces, The primary objectives were to determine flow interactions between the prediffuser and dump chamber to evaluate circumferential flow nonuniformities around transition pieces and combustors, and to identify the pressure loss mechanisms, Flow experiments were conducted in an approximately one-third geometric scale, 360-deg annular test model simulating practical details of the prototype including the support struts, transition pieces, impingement sleeves, and can-annular combustors. Wall static pressures and velocity profiles were measured at selected locations in the test model. A three-dimensional computational fluid dynamic analysis employing a multidomain procedure was performed to supplement the flow measurements, The complex geometric features of the test model were included in the analysis. The measured data correlated well with the computations. The results revealed strong interactions between the prediffuser and dump chamber flows. The prediffuser exit flow was distorted, indicating that the uniform exit conditions typically assumed in the diffuser design were violated. The pressure varied circumferentially around the combustor casing and impingement sleeve. The circumferential flow nonuniformities increased toward the inlet of the turbine expander, A venturi effect causing flow to accelerate and decelerate in the dump chamber was also identified This venturi effect could adversely affect impingement cooling of the transition piece in the prototype. The dump chamber contained several recirculation regions contributing to the losses. Approximately 1.2 dynamic head at the prediffuser inlet was lost in the combustor-diffuser, much of it in the dump chamber where the fluid passed though narrow pathways. A realistic test model and three-dimensional analysis used in this study provided new insight into the flow characteristics of practical combustor-diffuser systems.

    Journal Title

    Journal of Engineering for Gas Turbines and Power-Transactions of the Asme

    Volume

    120

    Issue/Number

    1

    Publication Date

    1-1-1998

    Document Type

    Article; Proceedings Paper

    Language

    English

    First Page

    24

    Last Page

    33

    WOS Identifier

    WOS:000071803700004

    ISSN

    0742-4795

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