ElsevierSerrano Cruz, JR.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Dombrovsky, A.; Tartoussi, H. (2016). Development and validation of a radial turbine efficiency and mass flow model at design and off-design conditions. Energy Abstract Turbine performance at extreme off-design conditions is growing in importance for properly computing turbocharged reciprocating internal combustion engines behaviour during urban driving conditions at current and future homologation cycles. In these cases, the turbine operates at very low flow rates and power outputs and at very high blade to jet speed ratios during transitory periods due to turbocharger wheel inertia and the high pulsation level of engine exhaust flow. This paper presents a physically based method that is able to extrapolate radial turbines reduced mass flow and adiabatic efficiency in blade speed ratio, turbine rotational speed and stator vanes position. The model uses a very narrow range of experimental data from turbine maps to fit the necessary coefficients. By using a special experimental turbocharger gas stand, experimental data have been obtained for extremely low turbine power outputs for the sake of model validation. Even if the data used for fitting only covers the turbine normal operation zone, the extrapolation model provides very good agreement with the experiments at very high blade speed ratio points; producing also good results when extrapolating in rotational speed and stator vanes position. RPerfect gas constant (Jkg −1 K −1 ) r Rotor radius (m) sd Standard deviation (−) 12 provided by manufacturers as a standard practice. Turbine maps are necessary 13 when using 1D or 0D modelling tools to predict the whole engine behaviour. In 14 1D modelling approach the one-dimensional unsteady non-homentropic mass, 15 momentum and energy conservation laws (Euler equations) are solved. Specific 16 source terms are used to simulate the friction and heat exchange in the pipes. 17 The 1D simulation codes make possible the calculation of gas dynamics engine 18 behaviour at low computational costs. Some engine components are modelled 19 4 with a 0D approach, using specific lumped parameter models or performance 20 maps. That is the case of cylinders, injectors, valves, compressors and turbines 21 which are coupled to the 1D computational domain as it is described in [4]. 22 For that reason, turbocharged ICE designers must rely on map extrapolation 23 tools when predicting engine performance outside of turbine design operative 24 conditions [5]. It is typical in pulsating flow conditions, requiring different mod-25 elling approaches similar to the proposed in [6], where meanline one-dimensional 26 models are discussed and in [7], where non-adiabatic pressure loss boundary con-27 dition is discussed. One-dimensional tools are also used in design process for 28 fast evaluation of turbine capabilities as in [8]. In [9] a Taylor series expansion 29 is used to develop a model able of predicting mass flow parameter of radial 30 turbines. 31 CFD models for turb...

ElsevierPayri González, F.; Broatch Jacobi, JA.; Serrano Cruz, JR.; Piqueras Cabrera, P. (2011). Experimental theoretical methodology for determination of inertial pressure drop distribution and pore structure properties in wall-flow diesel particulate filters (DPFs AbstractWall-flow particulate filters have been placed as a standard technology for Diesel engines because of the increasing restrictions to soot emissions. The inclusion of this system within the exhaust line requires the development of computational tools to properly simulate its flow dynamics and acoustics behaviour. These aspects become the key to understand the influence on engine performance and driveability as a function of the filter placement. Since the pressure drop and the filtration process are strongly depending on the pore structure properties -permeability, porosity and pore size -a reliable definition of these characteristics is essential for model development. In this work a methodology is proposed to determine such properties based on the combination of the pressure drop rement in a steady flow test rig and two theoretical approaches. The later are a lumped model and a one-dimensional unsteady compressible flow model. The purpose is to simplify the integration of particulate filters into the global engine modelling and development processes avoiding the need to resort to specific and expensive characterisation tests. The proposed methodology was validated against measurements of the response of an uncoated DPF under different flow conditions as cold steady flow, impulsive flow and hot pulsating flow.

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ElsevierSerrano Cruz, JR.; Olmeda González, PC.; Tiseira Izaguirre, AO.; García-Cuevas González, LM.; Lefebvre, A. (2013) AbstractThe aim of the present work is to show an approximation, through an experimental an theoretical study, to quantify the mechanical losses in a turbocharging system. These are linked to the dynamics in the turbo shaft bearings, both axial and radial. Theoretical and experimental methodologies are presented in order to develop a mechanical losses model. The experimental work consists on a measurement campaign in quasi-adiabatic operating conditions, while in the theoretical part, a mathematical model is developed taking into account the radial and axial bearings. The model uses some assumptions in order to solve the Navier-Stokes equations, leading to a simplified model which includes viscosity and the Reynolds number of the oil film formed on the bearings. The proposed model has shown a good agreement with the experimental data.

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In an internal combustion engine, twin entry turbine operates under different unequal admission conditions by feeding the turbine with a dissimilar amount of flow in each entry for a majority of the time. Despite of the impact on turbine performance, normal characteristic maps of these turbines are usually available only for full admission conditions. The current study

Wall-flow particulate filters are the basis to meet particulate emission standards concerning number and mass limits. The required balance between filtration efficiency and pressure drop demands the availability of computational tools able to predict and diagnose their combined response. In this paper a filtration model coupled with a gas dynamic particulate filter (PF) model based on the theory of packed beds of spherical particles is presented. The model takes as main assumption the experimentally well-known low soot penetration inside the porous wall. From this basis the description of the changes in filtration efficiency, pressure drop and deposits distribution are approached as a function of the soot loading level. The soot penetration inside the porous wall is shown to be a critical parameter dependent on the Peclet number. The transition from deep bed to cake filtration regime is also analysed accounting for macro-and micro-scale transition. Finally, the model is validated against experimental data obtained from several PFs. Flow properties advection along channels and the appropriate definition of the soot penetration and deposition dynamics lead to great accuracy in the modelling of the filtration efficiency, both overall and as a function of the particle size, as well as pressure drop.