Isothermal flow in a gas turbine combustor — a benchmark experimental study

Abstract

Abstract. An experimental investigation of the three-dimensional flow field within a water model of a can-type gas turbine combustion chamber is presented. Flow visualisation demonstrated that internal flow patterns simulated closely those expected in real combustors. The combustor comprised a swirl driven primary zone, annulus fed primary and dilution jets and an exit contraction nozzle. LDA measurements of the three mean velocity components and corresponding turbulence intensities were obtained to map out the flow development throughout the combustor. Besides providing information to aid understanding of the complex flow events inside combustors, the data are believed to be of sufficient quantity and quality to act as a benchmark test case for the assessment of the predictive accuracy of computational models for gas-turbine combustors. I IntroductionNew designs of gas turbine combustion systems are often aimed at simultaneous improvements in several, if not all, combustor performance parameters. High priority is usually given to expansion of the range of stable operating conditions, improvement of exit temperature traverses, and (more recently) reduced pollutant emissions. All of these features are crucially dependent on internal flow patterns and the associated rates of mixing. This fact alone has motivated the need for a better and more fundamental understanding of the processes taking place inside a combustion chamber. Further, no design techniques currently in general use can produce a combustor design that does not require subsequent development and the development process for a system which meets at least some of the above goals has also to date been largely experimental and empirical. Whilst this approach has been reasonably successful, increased use of computational procedures in parallel to experimentation would be expected to accelerate the development of improved combustor designs and reduce development costs. This is particularly evident in view of the number of interacting flow parameters within the combustor such as swirler flow, jet and cooling slot flows, influence of downstream exit contraction nozzle etc. Needless to say, the availability of suitable experimental data is also critical to the development and validation of mathematical models for combustor flows (Bruce et al. 1979;Coupland and Priddin 1986;Sturgess and Syed 1980). The motivation behind the investigation described herein was therefore twofold: (i) to provide comprehensive measurements which can be used with confidence to assess and further develop existing numerical models, and (ii) at the same time to provide data which allow better understanding of the parameters controlling the complex aerodynamics of combustor flows.Because of the complexity of such flows the approach usually adopted for the validation of numerical models (and thus the acquisition of suitable data) is to divide the real flow into a number of well-controlled component flows that emphasise only one or two of the important physical processes at a time. Many of t...

Effects of High Intensity, Large-Scale Freestream Combustor Turbulence on Heat Transfer in Transonic Turbine Blades

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A combustor-representative swirl simulator for a transonic turbine research facility

“…Velocity measurements performed in gas turbine combustors with high swirl at inlet confirm the persistence of swirl at the combustion chamber exit plane [9,10]. This highlights the need to explore the effects of swirl on the downstream turbine.…”

Flowfield Measurements for a Highly Turbulent Flow in a Stator Vane Passage

“…There have been a few studies documenting turbulence levels exiting the combustor. Kuotmos and McGuirk (1989) measured mean and fluctuating velocity profiles in a can-type combustion chamber and reported local axial turbulence levels up to 30% at the exit of the combustor. Moss (1992) also measured turbulence levels exiting a variety of gas turbine combustors and reported turbulence levels of 9% with a typical length scale being between 5 to 7 mm giving a length scale to pitch ratio of 0.1 < L x /P < 0.14 for a typical first stage stator vane.…”