The Impact of Combustor Turbulence on Turbine Loss Mechanisms

Folk, Masha; Miller, Robert J.; Coull, John D.

doi:10.1115/gt2019-90307

Cited by 7 publications

(2 citation statements)

References 28 publications

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“…The device also locally increases the flow turbulence at the stator inlet. In [16], the authors show how severe the impact of turbulence on turbine stage efficiency is, hence, the ability to simulate a combustor turbulence closer to that of a real engine is a plus that few experimental test rigs exploit. A rough estimate of the EWG turbulence intensity is found by calculating the standard deviation with respect to the phase averaged value (STD) of the total pressure.…”

Section: Introductionmentioning

confidence: 99%

Design and Commissioning of a Combustor Simulator Combining Swirl and Entropy Wave Generation

Notaristefano

Gaetani

2020

IJTPP

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Modern aero-engine combustion chambers burn a lean and premixed mixture, generating a turbulent flame which involves large heat-release fluctuations, thus producing unsteady temperature phenomena commonly referred to as entropy waves (EWs). Furthermore, to enhance the fuel air mixing, combustion air is swirled, leading to vorticity disturbances. These instabilities represent one of the biggest challenges in gas turbine design. In this paper, the design and testing of a novel entropy wave generator (EWG) equipped with a swirler generator (SG) are described. The novel EWG will be used in future works on the high-speed test rig at Politecnico di Milano to study the combustor–turbine interaction. The paper shows the process of the EWG geometry and layout. The EWG is able to produce an engine-representative EW, the extreme condition is at the maximum frequency of 110 Hz, a peak-to-valley temperature value of 20 °C and swirling angles of ±25° are measured. By virtue of these results, the proposed system outperforms other EWG devices documented in the literature. Furthermore, the addition of a swirling generator makes this device one of a kind.

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Section: Introductionmentioning

confidence: 99%

Design and Commissioning of a Combustor Simulator Combining Swirl and Entropy Wave Generation

Notaristefano

Gaetani

2020

IJTPP

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“…Therefore, it would be expected that the change due to mean dissipation is three times the change due to the production of TKE (Equation 7.14). This effect can be seen when comparing the low turbulence intensity and high turbulence intensity flat plate dissipation coefficients presented by Folk, Miller, & Coull (2019). They found the increase in turbulence intensity produced a relative change of 35% in the mean component and produced a relative change of only 11% in the fluctuating component.…”

Section: Relating the Change In Profile To Dissipation Coefficientmentioning

confidence: 83%

The Effect of Heat Transfer on Turbine Performance

Jardine

Miller

2021

Journal of Turbomachinery

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For over 50 years, high-pressure gas turbine blades have been cooled using air bled from the compressor. This cooling results in very high rates of heat transfer, both within the fluid and within the blade. The heat transfer often occurs across large differences in temperature and thus is highly irreversible. It is therefore surprising that little is understood about the effect of this heat transfer on turbine performance. This paper solves this problem by applying a new method known as mechanical work potential, or euergy, analysis. The key consequence of the analysis is that the value placed on all heat, relative to work, becomes set by the Joule (Brayton) cycle efficiency. This means that when heat is transferred locally within a flow, or when viscous reheat occurs, the value of this heat should be set by the Joule cycle efficiency. This paper demonstrates how the new method can be implemented both in the preliminary design systems and in the analysis of conjugate CFD solutions of complex engine representative components. The new method provides the cooling designer with a new way of raising turbine efficiency, a form of recuperation locally in the flow. This method offers the exciting potential to design cooling systems that, when added to a blade profile, actually reduces profile loss by up to 7.3%.

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A Framework for Estimating Effects of Combustor Turbulence on Turbine Profile Loss Generation

Gakhar

Folk

Greitzer

et al. 2023

Journal of Turbomachinery

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This paper describes a framework to quantify the effect of freestream turbulence, generated by mixing processes in a combustor, on turbulent boundary layer loss generation in the high pressure turbine downstream of the combustor. The regime of freestream turbulence common to gas turbine aero engines is identified and it is shown that the dissipation loss coefficient in this regime can be determined using existing measurements of the effect of freestream turbulence on skin friction. The paper shows that combustor-generated freestream turbulence can increase the profile loss coefficient of a typical high pressure turbine blade by as much as 28%. A relation has been derived between a non-dimensional turbulence parameter, which characterizes the freestream turbulence, and the increase in turbine boundary layer dissipation, which quantifies the decrease in turbine efficiency. The relation provides guidelines for combustor turbulence modifications that lead to turbine performance benefits. The framework has been applied in example trade studies which show that increasing the size of dilution ports and increasing the length of the combustor can decrease high pressure turbine profile loss generation to potentially increase stage efficiency up to 0.5%.

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The Impact of Combustor Turbulence on Turbine Loss Mechanisms

Cited by 7 publications

References 28 publications

Design and Commissioning of a Combustor Simulator Combining Swirl and Entropy Wave Generation

Design and Commissioning of a Combustor Simulator Combining Swirl and Entropy Wave Generation

The Effect of Heat Transfer on Turbine Performance

A Framework for Estimating Effects of Combustor Turbulence on Turbine Profile Loss Generation

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