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Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich., This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively., In commonly applied one-dimensional choking models for radial turbines, choked flow is assumed to appear in the geometrical throat of each stator and rotor. Coupled and complex three-dimensional effects are not considered. In order to analyze the internal aerodynamic in a radial turbine at off design conditions and before carrying out experimental tests, which in the case of automotive turbocharger are limited by their compact size, computational fluid dynamics (CFD) simulations stand out as a useful tool. This paper presents the study of a variable geometry turbine (VGT) of a commercial turbocharger at off design conditions reaching choked flow, analyzing the presence of this limiting conditions in the stator and rotor under different operation points and VGT positions. Reynolds-averaged Navier-Stokes (RANS) and unsteady RANS simulation have been performed to obtain the flow structures in stator and rotor. The results reveal that the choked effective area mostly depends on the stator vane position and pressure ratio. For the closed VGT position a standing shock wave appears on the stator suction side and expands through the vaneless space. For the opened VGT position the flow is choked at the rotor outlet. However, the evolution of the choked area highly depends on the rotational speed and the secondary flow. A strong interaction with the tip leakage vortex has been identified.

[EN] In the present paper, the mid-term performance of two different architectures of a solar-driven jet-ejector refrigeration system is numerically compared: the first one is fitted with a fixed-geometry jet-ejector while the second one is equipped with an adjustable spindle that modifies the jet-ejector area ratio. The jet-ejector behavior has been predicted with a validated computational fluid dynamics approach and the dynamic response of the overall system accounts for transient effects in a small parabolic trough collector and a hot thermal storage tank. The investigation shows that the adjustable jet-ejector allows for continuous and smooth operation in a much wider range of outdoor conditions. Additionally, it enables more efficient management of the thermal level in the hot storage system. As a result, the adjustable refrigeration system improves the performance indicators in all the warm months of the typical meteorological year under evaluation. The maximum improvement potential is found in May; the fixed-geometry system provides an average COPth of 0.34 while the adjustable system reaches an average COPth of 0.48 considering the same boundary conditions in both cases. (c) 2020 Elsevier Ltd and IIR. All rights reserved., Authors want to acknowledge to the institution "Conselleria dEducacio, Investigacio, Cultura i Esport de la Generalitat Valenciana" and its grant program "Subvenciones para la contratacion de personal investigador de caracter predoctoral" for doctoral studies (ACIF/2018/124) funded by The European Union

In the application of turbocharging and organic Rankine cycles (ORCs) the radial turbine can operate at high pressure ratio leading to the presence of choking inside the turbine. Information in this map region is needed to estimate the overall machine performance and to achieve an optimum matching of engine-turbocharger or an integration into ORCs. As a preliminar study before doing experimental tests in a turbocharger gas stand and before starting modeling activities, 3D CFD simulations were run for this paper. The occurrence of choking in the stator passage, in the vaneless space and in the rotor passage is categorized and analyzed under different operating conditions and VGT openings. The appearance of the shock wave depends strongly of the stator vane position and pressure ratio. In the analyzed turbocharger VGT turbine no choking has been identified in the throat of the stator vanes. In technically relevant closed VGT position choking was identified in the vaneless space. Whereas at open vane position the shock wave appears at the rotor throat and the Mach number can increase from the blade tip to the hub or from the hub to the tip depending on the rotational speed. Furthermore, tip leakage flow plays an important role, being responsible of subsonic regions in the rotor outlet although a big percentage of the section is choked.

[EN] Over the past few decades, the aerodynamic improvements of turbocharger turbines contributed significantly to the overall efficiency augmentation and the advancements in downsizing of internal combustion engines. Due to the compact size of automotive turbochargers, the experimental measurement of the complex internal aerodynamics has been insufficiently studied. Hence, turbine designs mostly rely on the results of numerical simulations and the validation of zero-dimensional parameters as efficiency and reduced mass flow. To push the aerodynamic development even further, a precise validation of three-dimensional flow patterns predicted by applied computational fluid dynamics (CFD) methods is in need. This paper presents the design of an up-scaled volute-stator model, which allows optical experimental measurement techniques. In a preliminary step, numerical results indicate that the enlarged geometry will be representative of the flow patterns and characteristic non-dimensional numbers at defined flow sections of the real size turbine. Limitations due to rotor-stator interactions are highlighted. Measurement sections of interest for available measurement techniques are predefined., The authors disclose receipt of the following financial support for the research, authorship, and/or publication of this article: This work was partly sponsored by the program "Ayuda a Primeros Proyectos de Investigacion (PAID-06-18), Vicerrectorado de Investigacion, Innovacion y Transferencia de la Universitat Politecnica de Valencia (UPV), Spain". The support given to Ms. N.H.G. by Universitat Politecnica de Valencia through the "FPI-Subprograma 2" (No.FPI-2018-S2-1368) grant within the "Programa de Apoyo para la Investigacion y Desarrollo (PAID-01-18)" is gratefully acknowledged

Each of the elements that make up the turbocharger has been gradually improved. In order to ensure that the system does not experience any mechanical failures or loss of efficiency, it is important to study which engine-operating conditions could produce the highest failing rate. Common failing conditions in turbochargers are mostly achieved due to oil contamination and high temperatures in the bearing system. Thermal management becomes increasingly important for the required engine performance. Therefore, it has become necessary to have accurate temperature and heat transfer models. Most thermal design and analysis codes need data for validation; often the data available fall outside the range of conditions the engine experiences in reality leading to the need to interpolate and extrapolate disproportionately. This article presents a fast three-dimensional heat transfer model for computing internal temperatures in the central housing for non-water cooled turbochargers and its direct validation with experimental data at different engine-operating conditions of speed and load. The presented model allows a detailed study of the temperature rise of the central housing, lubrication channels, and maximum level of temperature at different points of the bearing system of an automotive turbocharger. It will let to evaluate thermal damage done to the system itself and influences on the working fluid temperatures, which leads to oil coke formation that can affect the performance of the engine. Thermal heat transfer properties obtained from this model can be used to feed and improve a radial lumped model of heat transfer that predicts only local internal temperatures. Model validation is illustrated, and finally, the main results are discussed.

Wind energy importance has increased over the past decades. Energy generation by small turbines installed near urban locations has experienced noticeable growth. This work is focused on the development of a design methodology for a low power blade well suited for all the wind operation conditions. First, a complete Design of Experiments will be presented using the low computational cost tool Blade Element Momentum Theory (BEMT) in order to discard those designs which are clearly not suited to the requirements of the system. Later, the remaining were analyzed using a Computational Fluid Dynamics (CFD) methodology in order to account for three dimensional effects. The value of the left slope of the non-dimensional power curve has been found to be a key parameter for the design. This methodology has been validated with experimental results available from NREL Phase VI wind turbine, allowing to conclude that BEMT is capable to provide with pre-design accurate results which, nevertheless, should corrected by CFD. The results of the proposed design are analyzed and compared to the CFD predictions of a commercial existing blade designed to comply with similar working. For the proposed design, predictions indicate better behavior in terms of maximum power and controllability.

[EN] The heat transfer model can be used in a one-dimensional (1-D) engine simulation. When the engine speed is reduced to zero, the codes have been upgraded to calculate transient turbocharger thermal conditions. The turbocharger model has been used as an external plugin. Analysis of the temperature evolution at different parts of the turbocharger is done by using a hot spot engine cycle. A turbocharger bypassing strategy is done by means of a 9 bypass valve system. By using this method, instabilities can be found in the binary on-off state of an engine. During engine hot-stops, the lack of oil flow inside the turbocharger makes the trapped oil in the bearings burnt as the turbine housing exchanges heat with the central housing. Coke formation can appear and produce big reductions in turbocharger endurance, as bearings clogged and damage the shaft. Several strategies can be used in order to minimize possibilities of coke formation, including an increase in the turbocharger cooling during normal operation and the use of electrically-driven pumps acting after the engine is shut down. These strategies can be simulated in acceptable calculation times thanks to modelling strategy proposed in this paper. The presented methodology allows a detailed study of the temperature rise of the central housing of an automotive turbocharger after a hot-stop process, simulating several combinations of cooling strategies in order to find the optimum one in terms of minimising extra energy consumption per K of housing temperature reduction., We thank Przemek Kmiec for his support in the language editing. This work has been partially supported by the Spanish Ministry of Economyand Competitiveness through [grant No. TRA2013-40853-R].

A specific study of the uncertainties of turbine power output measured in turbocharger test benches is presented using the law of uncertainty propagation and the influence of the different terms that contribute to it is shown. Then, non-linear mixed integer mathematical programming algorithms used with the turbine power uncertainty expression become an essential tool to overcome the problem of selection new sensors to improve an existing test rig or to contribute to a new one. A method of optimisation is presented for two different scenarios: first, where the maximum cost is a constraint; second where the maximum uncertainty is a constraint and the total cost is minimised. When using a large transducers database, computational efforts may be reduced by solving the relaxed non-integer problem by means of sequential quadratic programming and then probing the ceilings and floors of the parameters to get an optimum approximation with low costs. A comparison between the linear uncertainty propagation model and Monte Carlo simulations is also presented, only showing benefits of the later method when computing high order statistical moments of the turbine power output probability distribution., This work has been partially supported by the Spanish Ministerio de Ciencia e Innovacion through Grant No. DPI2010-20891-C02-02 and by the Spanish Ministerio de Economia y Competitividad through Grant No. TRA2012-36954.

[EN] Centrifugal compressor performance at low mass flow rates has become an issue in the latest years due to engine downsizing and the increase of low-end torque request. The principal drawback of this operating region is the appearance of the surge phenomenon, which is strongly affected by the compressor inlet geometry. This work is addressed to study the impact of different inlet geometries on the compressor performance, including compressor efficiency, noise emission and surge margin. An engine test bench is set up with a centrifugal compressor and both steady and transient (tip-out) tests are performed in order to obtain a complete view of the influence of each configuration. The results show a clear sensitivity of the compressor parameters to the variations of the geometry upstream the compressor inlet. (C) 2016 Elsevier Ltd. All rights reserved., Daniel Tari is partially supported through contract FPI-S2-2015-1095 of Programa de Apoyo para la Investigacion y Desarrollo (PAID) of Universitat Politecnica de Valencia.

[EN] Nowadays, the turbocharger has become one of the key components for automotive spark-ignition engine improvements (fed with both liquid and gaseous fuels), as a support for the boosting and downsizing concept to reduce fuel consumption and exhaust emission. In gasoline engines, the usage of the waste-gate valve typically regulates the maximum boost pressure in the turbocharger system, to protect the engine and the turbocharger at high engine speeds. To improve the transient response at low engine speeds two-stage turbocharger is widely used. Two-stage systems are composed of several valves to regulate the flow to control the boosting of the system. Like, a by-pass valve between the turbines, a check valve between the compressor and a waste-gate valve for the low-pressure turbines. This paper deals with a methodology for characterizing the discharge coefficient of an electronic waste-gate valve in the turbocharger. To estimate the gas flow over the same in one-dimensional models, an empirical model is correlated and validated. For this, a constant stream experimental work has been carried out on a test rig at different valve position openings, with high turbine inlet temperatures. Finally, an optimal MAP of discharge coefficient has been drawn out through interpolation method, which can integrate into the full one-dimensional turbocharged engine model system, to calculate the actual mass flow through the waste-gate valve., The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was partially funded by FEDER and Government of Spain through Project TRA2016-79185-R.

[EN] During automotive urban driving conditions and future homologation cycles, automotive radial turbines experience transient conditions, whereby the same operate at very high blade speed ratios and, thus, at very low power outputs. Under those conditions, the turbine power output might not be enough to feed the mechanical power needs of the compressor. Typical fast one-dimensional full engine simulations rely on steady-state performance maps to characterize the turbocharger. Due to the restricting compressor braking power, extreme off-design measurements cannot be obtained in standard gas stands without using an external brake instead of the compressor or without using a motor attached to the turbocharger shaft. Such turbocharger assemblies cause shaft balancing issues inherent to the connection to a brake operating at high rotational speeds or need basic changes of the turbocharger geometry. This paper presents a novel approach for turbine performance map measurements at very low expansion ratio and very low mass flow without the aforementioned issues. The method uses the turbocharger compressor as a centrifugal turbine, providing mechanical power to the shaft and enabling turbine performance measurements from points of very high expansion ratio up to very low pressure ratio. It is even possible to measure at almost zero flow rate in the turbine when it consumes shaft power instead of producing it. This experimental procedure that can be applied to whatever turbocharger produces valuable information for the development and validation of turbine performance models aiming to extrapolate its behaviour at off-design conditions., The authors of this paper wish to thank M.A. Ortiz for his invaluable help during the experimental setup. The work has been partially supported by the Spanish Ministry of Economy and Competitiveness through grant number TRA2013-40853-R.

Fouling phenomenon is a key issue for EGR cooler operation. In spite of the fact that soot deposition is imposed by the characteristics of the exhaust gases flow, the design of the EGR cooler has a significant impact for effect on the engine. New combustion modes corresponding to new engine developments and combination of EGR system with other posttreatment devices make that fouling conditions for future generations of EGR coolers can be significantly different from previous applications from Euro 3 to Euro 5. An investigation has been performed in order to characterize the response of different EGR coolers designs for different conditions of the exhaust gases. As for the design, the technology selected has been tube-and-fin heat exchanger, which is a high performance technology that fits Euro 6 customer specifications. The variations in design have been made through modifications in fin characteristics, both in configuration and geometric dimensions. As for engine operation conditions, the exhaust gases characteristics have been modified from a standard calibration to get more severe fouling conditions, in terms of HC content, opacity, exhaust gas temperature and flow. The degradation of performance has been characterized through measurements of thermal efficiency and permeability. It can be concluded that HC content and opacity have a significant influence on fouling phenomena, and that EGR cooler optimum design is highly dependent on these exhaust gas conditions.

Nowadays, turbocharged internal combustion engines (ICEs) are very common in automotive powerplants, monopolizing the diesel sector and having a steadily increasing percentage in the gasoline one. In this frame, the interest in modeling the behavior of the turbomachinery components involved, with the ultimate goal of characterizing the performance of the turbocharged ICE, seems clear. A turbomachine can be simulated using three-dimensional computational fluid dynamics software, but its computational cost does not allow one to reproduce the whole turbocharger test rig. Moreover, the existence of long ducts requires a considerable computational time until the pressure reflections at the boundaries dissipate in order to reach a periodic solution. The use of non-reflecting boundary conditions reduces the length of ducts needed without introducing spurious wave reflections. An anechoic boundary condition (BC) based on the method of characteristics (MoC) has been previously developed, considering the case of an inviscid and adiabatic one-dimensional flow of a perfect gas. However, real flows do not behave in such an ideal manner. In this paper, the extension of the scope of the previous BC is sought. In this way, a methodology to evaluate the performance of the anechoic BC under these real flow situations is shown. The consideration of an ideal gas instead of perfect gas, the flow viscosity, and the non-homentropic flow make it necessary to modify the method of characteristics, since the Riemann invariants are not constant any more. In this frame they are referred to as Riemann variables. An additional issue that has been considered is the effect of swirl flow, such as the one in the turbine outlet, on the anechoic BC. Some improvements to be implemented in the BC are proposed in order to have a better performance in these real flow situations.

[EN] This paper describes the methodology followed to perform a co-simulation between 1D (OpenWAM) and 3D (FLUENT) CFD codes. The Method of Characteristics (MoC) has been chosen to transfer the information between the two domains by properly updating the boundary condition at the shared interface. A short explanation of the MoC is provided, including the modifications needed by the Riemann invariants when dealing with non-homentropic flow. The implementation of the coupling is explained, focusing on the particular approach required by FLUENT in order to obtain the Riemann invariants. Two validation tests have been performed. The Sod's problem has been used to test the numerical accuracy of the coupling methodology. On the other hand, an impulse test rig configuration has been simulated to show the potential capability of a co-simulation in terms of reducing the computational cost. In both cases a good agreement in the solution is found. © 2010 Elsevier Ltd., Roberto Navarro is indebted to the Universidad Politecnica de Valencia for its support through Grant Beca de Excelencia 2009. PAID-09-09.

In this article a new experimental technique is presented to measure the turbocharger surge limit in a regular engine test bench. It is known that the surge margin on engine tests may be very different from that obtained in a steady-flow gas-stand. In particular, surge is very dependent on the flow pattern produced by the compressor inlet duct and also on the piping upstream and downstream the compressor. The proposed technique that is based on the injection of pressurized air into the intake manifold is compared with the other ways of measuring the compressor map on engine. Some results with different compressor arrangements are presented and discussed. It is demonstrated that this technique allows for measuring not only the actual surge line but also the complete compressor performance map., This work has been funded by Spain's Ministerio de Ciencia y Tecnologia through project TRA2007-65433. The authors acknowledge R. Lujan for his valuable contribution to the tests. RL is indebted to the Generalidad Valenciana through the grant GRISOLIA/2008/009.

The paper presents a model of fixed and variable geometry turbines. The aim of this model is to provide an efficient boundary condition to model turbocharged internal combustion engines with zero- and one-dimensional gas dynamic codes. The model is based from its very conception on the measured characteristics of the turbine. Nevertheless, it is capable of extrapolating operating conditions that differ from those included in the turbine maps, since the engines usually work within these zones. The presented model has been implemented in a one-dimensional gas dynamic code and has been used to calculate unsteady operating conditions for several turbines. The results obtained have been compared with success against pressure–time histories measured upstream and downstream of the turbine during on-engine operation.

This article presents a two-stage turbocharged heavy-duty diesel (HDD) engine designed to fulfil the US2007 anti-pollution directive. This directive imposes very restrictive limits on the NOx and particle emissions of HDD engines. In this work, the possibility of combining particle traps in the exhaust line to reduce soot emissions with very high EGR rates to reduce NOx emissions is considered. This new generation engine implements two-stage turbocharging in order to improve the bsfc when the engine is working on steady conditions as well as to optimize the engine transient response. After carrying out the tests, the results were analyzed and the engine settings were adjusted to maximise its behaviour and minimise pollutant emissions. NOx and soot emission peaks were also analyzed at engine transient conditions in order to keep them under certain levels, and thus maintain the overall pollutant emissions to a level that is as low as possible. In summary, a double-stage turbocharging configuration can greatly improve engine driveability (between 23% and 36% depending on engine speed), while reducing NOx emissions during transient evolution without increasing opacity peaks beyond the stated limits.

Under the frame of Bologna system, alternative assessment methodologies gain significance in the evaluation process of the students. This article analyses the use of scoring rubrics for evaluating oral presentations of two different courses in aerospace engineering education, namely Aircraft Design and Aerodynamics II , at Universitat Politecnica de Valencia. The score obtained at the presentation represents a significant percentage of the final grade for both courses. It has been observed that the students find difficulties to keep timing limitations overall. In addition, rubrics have proved to be a powerful tool to enhance some skills of the students, such as critical thinking and self-evaluation, although they may lead to unfairly high grades nonetheless. http://dx.doi.org/10.4995/HEAd15.2015.391

This paper presents the development and validation of a one-dimensional radial turbine model able to be used in automotive turbocharger simulations. The model has been validated using results from a numerical 3D CFD simulation of stationary and pulsating flow in a variable geometry radial turbine. As the CFD analysis showed, the main non-quasi-steady behavior of the turbine is due to the volute geometry, so special care was taken in order to properly model it while maintaining low computational costs. The flow in the volute has been decomposed in its radial and azimuthal direction. The azimuthal flow corresponds to the flow moving along the volute, while the radial flow is computed by coupling its flow with a stator model. Although the stator caused fewer accumulation effects than the volute, a small accumulation model has been used for it, which also allows to compute the evolution of the flow inside the turbine with lower costs. The flow in the moving rotor can be considered quasi-steady, so a zero-dimensional model for the rotor has been developed. Several losses models where implemented for both the stator and the rotor. The results show good agreement with the CFD computations. 2014 Elsevier Ltd. All rights reserved., The authors are indebted to the Spanish Ministerio de Economia y Competitividad through Project TRA 2010-16205.

The 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, The authors of this paper wish to thank M.A. Ortiz and V. Ucedo for their invaluable work during the experimental setup and campaign, F.J. Arnau, Ph.D, for its excellent job maintaining and expanding Open WAMs code base and M.A. Reyes-Belmonte for all his hard and rigorous work extrapolating turbine maps and preparing and launching the simulations. This work has been partially supported by the Spanish Ministerio de Ciencia e Innovacion through grant number DPI2010-20891-C02-02.

Active control turbocharger (ACT) has been proposed as a way to improve turbocharger performance under highly pulsating exhaust flows. This technique implies that the variable geometry mechanism in the turbine is used to optimize its position as a function of the instantaneous mass flow during the engine cycle. Tests presented in the literature showed promising results in a pulsating gas-stand. In this work, a modeling study has been conducted at different engine conditions aimed to quantify the gain in on-engine conditions and to develop a strategy to integrate the ACT system within the engine. Different ways of changing the displacement of the variable mechanism have been analyzed by means of a one-dimensional gas dynamic model. The simulations have been carried out at constant engine operating points defined by fixed air-to-fuel ratio for different mechanism displacement functions around an average position that guarantees the desired amount of intake air. The benefits in overall engine efficiency are lower to those predicted in the literature. It can be concluded that it is not possible to use the ACT system to optimize the turbine operating point and at the same time to control the engine operating point., The authors wish to thank Mr. Fabrice Vidal from PSA Peugeot Citroen (France) for his contribution to the work presented here. The work has been partially funded by the Spain's Ministerio de Ciencia y Tecnologia through project TRA2007-65433.

This paper presents different aspects of air inlet behaviour near the inducer of a radial compressor and shows how the geometry can contribute to its stability and performance. Unfortunately, the space reserved for installation of an automotive turbocharger in a vehicle is constantly being reduced, so it is necessary to study the effects that elbows and abrupt changes in flow directions originate on the compressor performance. The work presented in this paper studies the effect that different 90° elbows have on the compressor with respect to its ideal, straight, no-elbow configuration, in order to obtain the best possible elbow configuration. The methodology followed has been to, initially, study different geometries in computational fluid dynamics code in order to obtain the best possible configuration. Then, several 90° elbows were constructed and characterized on a continuous flow test bench in order to validate the computational fluid dynamics results and to obtain optimum results. The elbows were then installed on a radial compressor and tested on a hot, continuous turbocharger test bench, where the compressor was characterized and maps were obtained with each different elbow. The results were compared with respect to the ideal, no-elbow configuration, which was taken as the base performance. After analysing the results obtained, it is possible to observe that in most of the cases, the elbows have a negative effect on the compression ratio, which tends to be reduced, especially at high rotor velocities and high air mass flow. On the other hand, the effect on the surge limit seems to be positive, as the surge line shifts to lower air mass flows, although the maximum mass flow allowed is reduced. It seems as if the compressor map shifts to the left with a reduction in compression ratio. From theoretical and experimental studies, it has been concluded that flow uniformity index and pressure loss are the most important factors affecting the performance of the compressor.

The article presents the development of the control manager of a parallel sequential turbocharger system. This control manager must decide the transition between the different operation modes of the boosting system. The control manager must protect the system from surge and over-speed risks.The methodology followed in the development process was based on the use of concurrence survey data from a similar engine, the simulation with a 1D code and finally the assessment on engine test bench. Real-life driving cycles were used during the development process, which were acquired in three different driving scenarios (city, road and mountain road).

The current global scenario, in which an ever increasing population with an ever growing transportation needs is coupled with a reduction in the fossil fuel production and increasing human-made pollution derived problems, leads automotive engine manufacturers to constant struggles for fuel consumption and emission reductions while keeping engine performance. One-dimensional simulation codes have become a key tool towards these objectives, but require continued accuracy refinements. Phenomena that were previously thought of a limited importance and could be extremely easily modelled now require the development of new methods to be accounted for. Among these phenomena are the turbocharger mechanical losses and the turbine behaviour under highly pulsating boundary conditions. This work is focused on the improvement of current one-dimensional models, for both mechanical losses prediction and high frequency pulsating flow turbine performance. After reviewing the state-of-the-art in experimental measurement and fast simulation of automotive turbochargers, this work presents first a experimental study of several turbochargers working under both steady-state and unsteady operating conditions, focusing on the general performance of the turbine and the losses in the power transmission between it and the compressor, even including internal pressure measurements in one of the tested units. All the measurements are corrected due to heat transfer, getting the purely adiabatic behaviour. Furthermore, a CFD simulation campaign of a radial turbine has been performed, thus obtaining a detailed description of its internal behaviour under highly pulsating flow. In the light of both the experimental and CFD-simulated results, a quasi-steady mechanical losses and a quasi-bidimensional turbine model have been developed. Both models have been validated using all the experimental and simulated data, proving a prediction accuracy improvements from the results of previous methods. The mechanical losses model offers a clear advantage over the usual practice of using a constant mechanical efficiency value for correcting the manufacturer’s turbocharger map, whereas the turbine model has demonstrated potential for turbine map extrapolation and has improved the instantaneous results over classic onedimensional turbine volute models for frequencies higher than 1000 Hz. Both models have been developed trying to keep a reduced computational cost, ensuring to exploit the specific characteristics of the processors where they are going to be run., García-Cuevas González, LM. (2014). Experiments and Modelling of Automotive Turbochargers under Unsteady Conditions [Tesis doctoral no publicada]. Universitat Politècnica de València. doi:10.4995/Thesis/10251/48458., TESIS