Mixed-flow turbines for automotive turbochargers: Steady and unsteady performance

Karamanis, N.; Martinez-Botas, Ricardo

doi:10.1243/14680870260189253

Cited by 57 publications

(38 citation statements)

References 13 publications

(3 reference statements)

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“…Similar results were also shown by Karamanis and Martinez-Botas [22], Szymko et al [17] and Rajoo and Martinez-Botas [21], who measured higher cycle-averaged efficiency in a single-entry turbine for higher speeds and frequencies. However, it must be noted that no consistent trend was observed in the cycle-averaged efficiency variation.…”

Section: Cycle Averaging and Comparison To Quasi-steadysupporting

confidence: 85%

Unsteady performance analysis of a twin-entry variable geometry turbocharger turbine

Rajoo

Romagnoli

Martinez-Botas

2012

Energy

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The unsteady performance of a twin-entry variable geometry turbine for an automotive turbocharger is presented. A single-entry variable geometry turbine was initially designed based on a commercial nozzle-less turbine. The variable geometry single-entry volute was later modified to twin-entry through partitioning. A comprehensive range of steady testing and evaluation was also conducted as part of this project, which is discussed by Romagnoli et al. [1]. The unsteady curves of the twin-entry turbine exhibited the conventional looping characteristics representing filling and emptying effects, which was also the case for the nozzleless and single-entry nozzled turbine. The swallowing capacity of the twin-entry turbine, during full admission testing, was recorded to be inconsistent between the two entries, in particular they were at different pressure ratio levels -the shroud end entry was in most cases INTRODUCTIONA turbocharger turbine operates under unsteady conditions due to the pulsating nature of the exhaust gases. In consequence, twin-entry turbines are generally designed and used for better energy extraction from the pulsating exhaust gases. Two banks of exhaust manifolds feed each entry of the turbine so that the "rotor windmill" is minimized as the mass flow drops to zero. Thus, there is a need for experimental work to understand the unsteady-state performance of a twin-entry turbine in comparison to the single-entry and nozzleless unit.Wallace and Blair [2] and Benson and Scrimshaw [3] presented the earliest systematic study on the unsteady performance of a radial turbine. These were followed by Wallace et al. [4], Miyashita et al. [5], Benson [6] and Kosuge et al. [7]. All these investigations were limited by the inability of the instruments to instantaneously measure all the relevant performance parameters. Thus, only the static pressure was measured instantaneously, while the mass flow rate, temperature, speed and torque were measured as time-mean values. This remains similar for the investigation presented by Capobianco et al. [8,9] and Capobianco and Gambarotta [10]. Research work by Capobianco et al. [8,9] Fig. 1 illustrates the turbine configurations used for the current study, which was designed in progression from nozzleless single-entry to nozzled twin-entry. The details of the turbine design stages are described in Romagnoli et al. [1]. The experimental facility available in Imperial College EXPERIMENTAL FACILITYLondon is a simulated reciprocating engine test-bed for turbocharger testing. The facility has the capability of conducting steady and unsteady flow testing of single and twin-entry turbines. A schematic diagram of the turbine test rig is shown in Fig. 2. The test rig is equipped with an eddy current dynamometer, which enables turbine testing within a large velocity ratio range [7,8]. The test-rig is supplied by screw-type compressors, capable to delivering air up to 1.2 kg/s mass flow rate at a maximum pressure of 5 bars (absolute). The two separated streams of airflow in e...

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Section: Cycle Averaging and Comparison To Quasi-steadysupporting

confidence: 85%

Unsteady performance analysis of a twin-entry variable geometry turbocharger turbine

Rajoo

Romagnoli

Martinez-Botas

2012

Energy

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“…The rotational speed of the turbine simulations was 50000 r/min, which was a main operation condition of the turbocharger while the design speed was 70000 r/min. Another reason for choosing this running speed is that it may have more obvious unsteady characteristics in the turbine at a lower running speed [15,16]. The static temperature imposed at the inlet boundary was 873 K. The residuals of steady simulations were less than 10 5 and errors between inlet and outlet mass flow rates were less than 0.1% after 4000 iteration steps, which meant that good convergence was obtained.…”

Section: Resultsmentioning

confidence: 99%

Effects of pulse flow and leading edge sweep on mixed flow turbines for engine exhaust heat recovery

Zhang

Chen

Zhuge

et al. 2011

Sci. China Technol. Sci.

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Recovery of heat energy from internal combustion engine exhaust will achieve significant road transportation CO 2 reduction. Turbocharging and turbogenerating are most commonly used technologies to recover engine exhaust heat energy. Engine exhaust pulse flow can significantly affect the turbine performance of turbocharging and turbogenerating systems, and it is necessary to consider the pulse flow effects in turbine design and performance analysis. An investigation was carried out by numerical simulation on the mixed flow turbine pulse flow performance and flow fields. Results showed that the variations of the turbine efficiency and flowfiled under pulsating flow conditions demonstrate significant unsteady effects. The effect of blade leading edge sweep on turbine pulse flow performance was studied. It is shown that increasing of the leading edge sweep angle can improve the turbine average instantaneous efficiency by about 2 percent under pulsating flow conditions. waste heat recovery, mixed flow turbine, pusle flow Citation:Zhang Y J, Chen L, Zhuge W L, et al. Effects of pulse flow and leading edge sweep on mixed flow turbines for engine exhaust heat recovery.

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“…The power turbines were created using a generic turbine map which provided a suitable combination of pressure ratio, mass flow rate and efficiency. The maps were subsequently scaled in mass flow, in keeping with literature [27], to provide a suitable range of mass flow rates for the engine used in this project. The power output of each turbogenerator was determined by the mass flow scaling factor used in each turbine map.…”

Section: Turbogenerator Modelmentioning

confidence: 99%

Whole-vehicle modelling of exhaust energy recovery on a diesel-electric hybrid bus

Briggs

McCullough

Spence

et al. 2014

Energy

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Hybrid vehicles can use energy storage systems to disconnect the engine from the driving wheels of the vehicle. This enables the engine to be run closer to its optimum operating condition, but fuel energy is still wasted through the exhaust system as heat. The use of a turbogenerator on the exhaust line addresses this problem by capturing some of the otherwise wasted heat and converting it into useful electrical energy.This paper outlines the work undertaken to model the engine of a diesel-electric hybrid bus, coupled with a hybrid powertrain model which analysed the performance of a hybrid vehicle over a drive-cycle. The distribution of the turbogenerator power was analysed along with the effect on the fuel consumption of the bus. This showed that including the turbogenerator produced a 2.4% reduction in fuel consumption over a typical drive-cycle. The hybrid bus generator was then optimised to improve the performance of the combined vehicle/engine package and the turbogenerator was then shown to offer a 3.0% reduction in fuel consumption. The financial benefits of using the turbogenerator were also considered in terms of fuel savings for operators. For an average bus, a turbogenerator could reduce fuel costs by around £1200 per year.

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Mixed-flow turbines for automotive turbochargers: Steady and unsteady performance

Cited by 57 publications

References 13 publications

Unsteady performance analysis of a twin-entry variable geometry turbocharger turbine

Unsteady performance analysis of a twin-entry variable geometry turbocharger turbine

Effects of pulse flow and leading edge sweep on mixed flow turbines for engine exhaust heat recovery

Whole-vehicle modelling of exhaust energy recovery on a diesel-electric hybrid bus

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