Detailed Flow Measurements at the Exit of a Mixed Flow Turbine Under Steady Flow Conditions

Karamanis, N.; Martinez-Botas, Ricardo; Su, C. C.

doi:10.1115/99-gt-342

Cited by 7 publications

(5 citation statements)

References 3 publications

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“…Figure 6 shows the static unsteady pressure However, in the present test facility the inlet static pressure and mass flowrate, which are used to calcu-taken at the above-mentioned planes; postprocessing of this figure shows that the only appro-late the instantaneous turbine isentropic power, are measured at the turbine inlet, while the instan-priate time to shift the signal is given by the sonic travel time. This is in accordance with Arcoumanis taneous rotational speed, from which the instantaneous torque and turbine actual power are et al [11]. This discussion of the travel time is of the utmost importance in order not to present unrealistic deduced, is measured at the impeller shaft.…”

Section: Unsteady Flow Performancesupporting

confidence: 85%

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

Karamanis

Martinez-Botas

2002

International Journal of Engine Research

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Turbochargers are finding increasing application to automotive diesel engines as cost effective means for improving their power output and efficiency, and reducing exhaust emissions; these requirements have led to the need for highly loaded turbocharger turbines. A mixed-flow turbine is capable of achieving its peak isen-tropic efficiency at reduced velocity ratios compared to a typical radial inflow turbine; it is therefore possible to improve the turbocharger/engine matching. These turbines differ from the commonly used radial turbines in that the flow approaches the rotor in the non-radial direction; in the extreme a mixed-flow turbine would become an axial machine. The steady and unsteady performances of a mixed-flow turbocharger turbine with a constant blade inlet angle have been investigated. The steady flow results indicated that the mixed-flow turbine obtains a peak efficiency (total-to-static) of 75 per cent at a velocity ratio of 0.61, compared with that of a typical radial-inflow turbine which peaks at a velocity ratio of 0.7. The performance and flow characteristics were found to deviate significantly from the equivalent steady state values commonly used in turbocharger turbine design.

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Section: Unsteady Flow Performancesupporting

confidence: 85%

“…[23] and Arcoumanis et al [11]. The other approach is that if an accurate time-averaged static tempera-ameter is plotted against the pressure ratio in Fig.…”

Section: Unsteady Flow Performancementioning

confidence: 99%

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

Karamanis

Martinez-Botas

2002

International Journal of Engine Research

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“…The valve timings were taken from Wallace and Cox [6 ], while the 55 per cent). A compressor non-dimensional speed of 100 per cent gives a maximum compressor pressure ratio turbine size was scaled according to data from Karamanis [7]. Fuel injection timing was optimized to of approximately 3:1.…”

Section: The Main Design Parametersmentioning

confidence: 99%

Turbocharger motor-generator for improvement of transient performance in an internal combustion engine

Panting

Pullen

Martinez-Botas

2001

Proceedings of the Institution of Mechanical Engineers, Part D:

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Turbocharging of internal combustion engines is an established technology used for the purpose of increasing both power density and in some cases the cycle eYciency of diesel engines relative to naturally aspirated engines. However, one signi cant drawback is the inability to match the characteristics of the turbocharger to the engine under full load and also to provide suYciently good transient response. Under many conditions this results in reduced eYciency and leads to higher exhaust emissions. The design of turbocharger components must be compromised in order to minimize these drawbacks throughout the entire operating range. However, when shaft power can be either added to or subtracted from the turbocharger shaft by means of a direct drive motor-generator, an additional degree of freedom is available to the designer to achieve a better turbocharger-engine matching. Both engine eYciency and transient response can be signi cantly improved by means of this method, normally described as hybrid turbocharging. This paper describes the results of a theoretical study of the bene ts of hybrid turbocharging over a basic turbocharged engine in both steady state and transient operation. The new system and its bene ts are described and four diVerent engineturbocharger systems are analysed in addition to the baseline engine. The main conclusion of the paper is that a signi cant increase in design point cycle eYciency can be aVorded by re-matching the turbocharger components under steady state conditions while at the same time improving full throttle transient performance. Emissions are not considered in this paper. è eYciency NOTATION r density (kg/m3) ö angular velocity (rad/s) a acceleration (m/s2) a r resistance coeYcient (N/kg) A area (m2) Subscripts b r resistance coeYcient (N s/kg m) C D drag coeYcient accel acceleration E energy (J ) atm atmospheric I moment of inertia (kg m2) comp compressor design parameter k ratio of forward speed to angular velocity IC internal combustion engine m truck mass (kg); mass ow (kg/s) inlet inlet manifold n number of cylinders load aerodynamic load N rotational speed (r/s) motor electric assist motor generator t time (s) TC turbocharger T torque (N m) truck typical truck v velocity (m/s) turb turbine V s swept volume (m3) vol volumetric W work (J ) The MS was

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“…Newton [10] experimented with a symmetric double entry turbine with a mixed flow turbine rotor 'A' which was designed in Imperial College London [15], and has shown that peak efficiency can be achieved up to 79.7% with nozzle setting in steady state condition. A year later, Martinez-Botas and Sakai [16] designed an asymmetric double entry turbine which they claim can improve flow balance around turbine wheel during high EGR rate and subsequently improved energy extraction capability.…”

Section: Introductionmentioning

confidence: 99%

Influence of Double Entry Volute on Incidence Angle Variation Under Steady Flow: Numerical Investigation

Gurunathan

Khairuddin

Shah

et al. 2020

CFDL

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EGR extraction from one side of the exhaust manifold creates imbalance of mass flow in a double entry turbine. To overcome this problem, the asymmetric double entry turbine was introduced. The performance maps of this turbine were obtained through extensive test configurations in both steady and unsteady flow conditions at Imperial College cold flow test rig. Two main configurations were investigated; nozzleless and nozzle vane setting. Nevertheless, no attempt has been made to compare the performance of asymmetric double entry turbine to that of the symmetric counterpart. One way to make comparison between these two double entry turbine volutes, is by using numerical simulation. This is achieved by using ANSYS CFX tool in this paper. A symmetric double entry volute CAD model is developed using the same A/R ratio as the asymmetric counterpart, adopting the same mixed flow rotor, inlet and exit ducts. The steady state numerical investigation was conducted at two turbine speeds, 30k RPM and 48k RPM, for the nozzleless configuration. Steady state experimental results of asymmetric double entry turbine are set as the boundary condition in the simulation. Validation of the simulation results with that of the experimental data, shows good agreements for both speed lines for the asymmetric double entry turbine. The symmetric double entry turbine recorded peak efficiencies; lower by 2.8% and 8%, at 30k RPM and 48k RPM respectively, compared to that of asymmetric double entry turbine. The results of steady state conditions of the asymmetric double entry turbine suggest that the distribution of the incidence angle is better than the symmetric double entry turbine as it is able to maintain the incidence angle at off-design and design point operating condition within the same range.

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Detailed Flow Measurements at the Exit of a Mixed Flow Turbine Under Steady Flow Conditions

Cited by 7 publications

References 3 publications

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

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

Turbocharger motor-generator for improvement of transient performance in an internal combustion engine

Influence of Double Entry Volute on Incidence Angle Variation Under Steady Flow: Numerical Investigation

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