Simulation of Pulsating Flow Unsteady Operation of a Turbocharger Radial Turbine

Máček, Ján; Vítek, Oldřich

doi:10.4271/2008-01-0295

Cited by 35 publications

(23 citation statements)

References 14 publications

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“…Where K 1 has been already defined in equation (18) and K* 2 and K 3 are defined as: K expression is further expanded as a function of  considering that A eff to A 0 ratio comes from equation (3) and that the angle  1 ( figure 10) is a linear function of the blade to jet speed ratio, equation (19). Equation (27) has been applied to the turbine data, measured at constant U* and described in previous sections, in order to get the efficiency extended map.…”

Section: Constant Corrected Rotor Tip Speed Testsmentioning

confidence: 99%

“…There are several works developing this kind of models for the losses found in the turbine, and specifically the tip losses [16] [17]. Other authors [18] have recently developed a 1D model which intends to represent the turbine behaviour under unsteady flow conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Low turbine inlet temperature means as low as required in order to avoid heat transfer effects, and therefore to be able to measure adiabatic efficiency, but at the same time avoiding freezing air mist at turbine inlet. Futral [18] reports a specific value of 55.74 ºC, the VGT was tested in a range between 66ºC and 80ºC and the rest of the sources does not offer more precision about this datum.…”

Section: Introductionmentioning

confidence: 99%

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A physically based methodology to extrapolate performance maps of radial turbines

Payri

Serrano

Fajardo

et al. 2012

Energy Conversion and Management

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This paper details a physical based methodology to perform an extrapolation of the radial turbine performance maps, both mass flow characteristics and the efficiency curve. This method takes into account a narrow range of experimental data, which is usually the data available when such turbines are part of a turbocharger. Therefore, the extrapolation methodology is especially useful when data from third parties are being used or when the compressor of a turbocharger is used as turbine brake in a gas stand. The nozzle equation is used to develop an interpolation and extrapolation of the mass flow rate trough the turbine. Then, specific information is extracted from this extrapolation and is fed into a total-to-static efficiency equation to carry out an extension of the efficiency curve. This equation is developed using the definition of the total-to-static efficiency, velocity triangles and thermodynamic and fluid fundamental equations.This procedure has been applied to five radial turbines of different sizes and types. Results are compared against experimental information available in the literature or provided by the turbine manufacturers and a good agreement has been found between theoretical and experimentally estimated data.Keywords: Turbochargers, radial turbines, efficiency and mass flow rate maps extrapolation, physical equations based extrapolation. ------------------------------- Greek --------------------------------- Subscripts INTRODUCTIONA way to characterize the performance of a radial inflow turbine widely used in a turbocharger is via a turbine map. Turbine maps usually are presented using two separate plots: one for the mass flow rate and one for the energy conversion efficiency, which usually is taken as the total-to-static efficiency. The former chart is presented as the corrected mass flow ( * m  ) as a function of the totalto-static expansion ratio (ER). The corrected mass flow ( * m  ) is defined as the mass flow rate multiplied by a ratio between the square root of the turbine stagnation inlet temperature and the turbine stagnation inlet pressure [1]. The other chart is the total-to-static efficiency ( ts ) as a function of the blade to jet speed ratio (), which is a ratio of the rotor tip linear velocity to the isentropic velocity through the turbine stage, for different turbine rotational speeds [1]. [5] used a radial compressor instead of a dynamometer to enable increased power of larger turbines to be absorbed. Szymko [6] developed an installation where an eddy current dynamometer was used in order to absorb the power of the turbine and for providing a low known inertia of the rotating assembly, which increases the measurement accuracy of the instantaneous torque.In the continuous flow test bench at Universidad Politécnica de Valencia, the approach is to use a compressor as a braking device [7]. In this last case, a collection of only a narrow range of data is possible, due to the surge and choke limits of the compressor, so a limited widespread of the data is availabl...

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Section: Constant Corrected Rotor Tip Speed Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A physically based methodology to extrapolate performance maps of radial turbines

Payri

Serrano

Fajardo

et al. 2012

Energy Conversion and Management

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“…Final comment concerns possible application of 1 -D radial turbine model which was developed at CTU. The model is based on [14,[16][17][18] and it was successfully applied in a case of fixed geometry turbine for heavy duty diesel engine and for VGT turbine for medium duty diesel engine. Such model has predictive capability based on 1 -D CFD -it can be applied to extrapolate turbine maps or improve turbine model performance under strongly unsteady conditions (including engine transient response).…”

Section: Turbocharger Modelmentioning

confidence: 99%

Optimization of 2‑Stage Turbocharged Gas SI Engine Under Steady State Operation

Vítek¹,

Máček²,

Klima³

et al. 2017

Journal of Middle European Construction and Design of Cars

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The proposed paper deals with an optimization of a highly-turbocharged large-bore gas SI engine. Only steady state operation (constant engine speed and load) is considered. The paper is mainly focused on theoretical potential of 2-stage turbocharging concept in terms of performance and limitation. The results are obtained by means of simulation using complex 0-D/ 1-D engine model including the control algorithm. Different mixture composition concepts are considered to satisfy different levels of NOx limit - fresh air mixed with external cooled EGR is supposed to be the right approach while optimal EGR level is to be found. Considering EGR circuit, 5 different layouts are tested to select the best design. As the engine control is relatively complex (2-sage turbocharger group, external EGR, compressor blow-by, controlled air excess), 5 different control means of boost pressure were considered. Each variant based on above mentioned options is optimized in terms of compressor/turbine size (swallowing capacity) to obtain the best possible BSFC. The optimal variants are compared and general conclusions are drawn.

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“…In the case of strong engine downsizing, also turbocharger compressor often works under unsteady flow condition, due to the reduced volume interposed between the outlet compressor section and the engine intake valves. As a consequence, the unsteady flow turbocharger behaviour needs to be experimentally investigated in order to accurately predict the turbine and compressor performance within simulation models (8,9).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation under unsteady flow conditions on turbocharger compressors for automotive gasoline engines

Marelli

Capobianco

2012

10th International Conference on Turbochargers and Turbocharging

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Simulation of Pulsating Flow Unsteady Operation of a Turbocharger Radial Turbine

Cited by 35 publications

References 14 publications

A physically based methodology to extrapolate performance maps of radial turbines

A physically based methodology to extrapolate performance maps of radial turbines

Optimization of 2‑Stage Turbocharged Gas SI Engine Under Steady State Operation

Experimental investigation under unsteady flow conditions on turbocharger compressors for automotive gasoline engines

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