An audit of aerodynamic loss in a double entry turbine under full and partial admission

Newton, Peter; Copeland, Colin; Martinez-Botas, Ricardo; Seiler, Martin

doi:10.1016/j.ijheatfluidflow.2011.10.001

Cited by 53 publications

(19 citation statements)

References 16 publications

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“…This is also found in the doctoral thesis of Shaaban [137] who suggested that the blade speed ratio is the most commonly used parameter to define the turbine efficiency. This phenomenon seen when plotting efficiency vs. BSR is also found and shown by turbocharger testing and research [138]. It is debatable how the turbine works under unsteady flow -Westin [126] showed that the blade speed ratio at maximum efficiency could stray away from the standard value of 0.707, at non-steady conditions.…”

Section: Turbinementioning

confidence: 68%

A review on the thermodynamic optimisation and modelling of the solar thermal Brayton cycle

Roux

Bello‐Ochende

Meyer

2013

Renewable and Sustainable Energy Reviews

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Many studies have been published on the performance and optimisation of the Brayton cycle and solar thermal Brayton cycle showing the potential, merits and challenges of this technology. Solar thermal Brayton systems have potential to be used as power plants in many sun-drenched countries. It can be very competitive in terms of efficiency, cost and environmental impact. When designing a system such as a recuperative Brayton cycle there is always a compromise between allowing effective heat transfer and keeping pressure losses in components small. The high temperatures required in especially the receiver of the system presents a challenge in terms of irreversibilities due to heat loss. In this paper, the authors recommend the use of the total entropy generation minimisation method. This method can be applied for the modelling of a system and can serve as validation when compared with first-law modelling. The authors review various modelling perspectives required to develop an objective function for solar thermal power optimisation, including modelling of the sun as an exergy source, the Gouy-Stodola theorem and turbine modelling.With recommendations, the authors of this paper wish to clarify and simplify the optimisation and modelling of the solar thermal Brayton cycle for future work. The work is applicable to solar thermal studies in general but focuses on the small-scale recuperated solar thermal Brayton cycle.2

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Section: Turbinementioning

confidence: 68%

A review on the thermodynamic optimisation and modelling of the solar thermal Brayton cycle

Roux

Bello‐Ochende

Meyer

2013

Renewable and Sustainable Energy Reviews

View full text Add to dashboard Cite

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“…The entropy generation of the interspace region, S.s (suction-side) passage, and P.s (pressure-side) passage significantly increase in partial admission rather than equal admission [8]. The highest entropy generation of the interspace area occurs near the tongues region where the high-velocity fluid from the flowing entry mixes with the lower velocity fluid in the non-flowing region [8]. This mixing, which dissipates some useful work, can be eliminated by changing the geometry of two stator vanes in the tongue region, with the aim of isolating two sectors completely.…”

Section: Methodsmentioning

confidence: 91%

“…In partial admission conditions, the efficiency is lower than the equal admission conditions. The entropy generation of the interspace region, S.s (suction-side) passage, and P.s (pressure-side) passage significantly increase in partial admission rather than equal admission [8]. The highest entropy generation of the interspace area occurs near the tongues region where the high-velocity fluid from the flowing entry mixes with the lower velocity fluid in the non-flowing region [8].…”

Section: Methodsmentioning

confidence: 97%

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Radial Gradient Pressure Effects on Flow Behavior in a Dual Volute Turbocharger Turbine

2018

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The pressure gradient in the dual volute radial turbocharger turbines is the primary source of the vortices’ formation in rotor passages. The effects of the upstream non-uniform flow conditions on the development of secondary flows are not well known. In this study, the effect of highly skewed and non-uniform mass flow on the secondary vortices in different admission cases in a dual entry turbine was investigated using CFD modeling. The results agree well with the experiment, and show that increasing the inequality of the pressure between the entries leads to a reduction in the turbine’s performance. Some useful energy dissipates due to mixing the flows of the entries. Isolating the rotor sectors in the tongues region was applied with the purpose of limiting the mixing. Also, the vortices’ behavior in the rotor passages with different surface pressure ratios for the passage sides were investigated for both equal and partial admission. The surface pressure of the airfoil pressure side was more effective on the tip and trailing edge vortex than the suction side, while the leading-edge root vortex did not change by any variation in the surface pressure ratio. The vortices’ center location shifted with the pressure variation, and consequently, by decreasing the pressure level, the center of the tip vorticity turned to the upstream sections, and the leading-edge root vortex center moved closer to the pressure side.

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“…Entropy generation rate is a useful concept, and as the CFD simulation tools developed a lot during the last decades, it is convenient to be calculated now. Since 2000, several researchers have reported the turbine loss mechanisms by the concept of entropy generation rates [36,37]. (a) reduced mass flow rates versus total-to-static pressure ratios at five reduced rotating speeds; and (b) total-to-static isentropic efficiencies versus velocity ratios.…”

Section: Turbine Loss Mechanisms Comparisonmentioning

confidence: 99%

Similarity Theory Based Radial Turbine Performance and Loss Mechanism Comparison between R245fa and Air for Heavy-Duty Diesel Engine Organic Rankine Cycles

Zhang

Zhuge

Zhang

et al. 2017

Entropy

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Organic Rankine Cycles using radial turbines as expanders are considered as one of the most efficient technologies to convert heavy-duty diesel engine waste heat into useful work. Turbine similarity design based on the existing air turbine profiles is time saving. Due to totally different thermodynamic properties between organic fluids and air, its influence on turbine performance and loss mechanisms need to be analyzed. This paper numerically simulated a radial turbine under similar conditions between R245fa and air, and compared the differences of the turbine performance and loss mechanisms. Larger specific heat ratio of air leads to air turbine operating at higher pressure ratios. As R245fa gas constant is only about one-fifth of air gas constant, reduced rotating speeds of R245fa turbine are only 0.4-fold of those of air turbine, and reduced mass flow rates are about twice of those of air turbine. When using R245fa as working fluid, the nozzle shock wave losses decrease but rotor suction surface separation vortex losses increase, and eventually leads that isentropic efficiencies of R245fa turbine in the commonly used velocity ratio range from 0.5 to 0.9 are 3%-4% lower than those of air turbine.

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An audit of aerodynamic loss in a double entry turbine under full and partial admission

Cited by 53 publications

References 16 publications

A review on the thermodynamic optimisation and modelling of the solar thermal Brayton cycle

A review on the thermodynamic optimisation and modelling of the solar thermal Brayton cycle

Radial Gradient Pressure Effects on Flow Behavior in a Dual Volute Turbocharger Turbine

Similarity Theory Based Radial Turbine Performance and Loss Mechanism Comparison between R245fa and Air for Heavy-Duty Diesel Engine Organic Rankine Cycles

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