On the influence of inlet elbow radius on recirculating backflow, whoosh noise and efficiency in turbocharger compressors

[EN] While the influence of inlet geometry on turbocharger compressor behaviour has usually been investigated in terms of performance, surge margin and efficiency, data is scarce regarding the impact of the inlet flow field onto the noise emission. In many applications where tight packaging is required, a 90° elbow is placed just upstream of the compressor inducer. This can create a distortion of the incoming flow that affects the turbocharger operation; a distortion that is related to the radius of the elbow. In this experimental investigation three 90° elbow inlets are tested, measuring the in-duct sound intensity through acoustic beamforming, the spectral signature of the noise, and the distortion of the high temperature backflow typical of partially stalled conditions by means of thermocouple arrays. Results show that a tighter elbow radius not only impacts efficiency but also increases inlet noise at conditions close to surge. Spectral analysis shows that this increase is mainly produced in the form of a medium frequency broadband noise usually known as `whoosh¿ in the literature. On the other hand, effect on the outlet is less noticeable. Measurements of the recirculated backflow distortion in terms of circumferential skewness show good correlation with whoosh noise increase, indicating that flow distortion caused by tighter elbows at marginal surge conditions facilitates the transmission of whoosh noise oscillations to the inlet duct, worsening the acoustic behaviour of the system.The equipment used in this work has been partially supported by the Spanish Ministerio de Economia y Competitividad through grant DPI2015-70464-R and by FEDER project funds 'Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)' framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economia y Competitividad. F. Roig is partially supported through the Programa de Apoyo para la Investigacion y Desarrollo of Universitat Politecnica de Valencia (PAID-01-17).Broatch, A.; Ruiz, S.; Garcia Tiscar, J.; Roig-Villanueva, F. (2018). On the influence of inlet elbow radius on recirculating backflow, whoosh noise and efficiency in turbocharger compressors. Experimental Thermal and Fluid Science. 96:224-233. https://doi.org/10.1016/j.expthermflusci.2018.03.011S2242339

On the Design of Heat Exchangers for Altitude Simulators

[EN] Altitude simulators for internal combustion engines are broadly used in order to simulate different atmospheric pressure and temperatures on a test bench. One of the main problems of these devices is their outlet temperature and in order to control it, at least one heat exchanger is needed. A methodology to define, select and analyses the best heat exchanger that fulfill the requirements is presented. The methodology combines CFD and 0D models with experimental test. The combination of these tools allows to adjust both the 0D and the CFD models. The adjusted 0D model will be used to perform parametric analysis that will help to select the best geometrical combinations considering heat transfer and pressure losses while the CFD model will help to find possible local deficiencies on the designed Heat Exchanger and, therefore, try to improve it. Finally, the adjusted 0D model have been used to perform parametric studies changing the most important geometric characteristics to analyze the effect on HEX performance.Broatch, A.; Olmeda, P.; Garcia Tiscar, J.; Roig-Villanueva, F. (2021). On the Design of Heat Exchangers for Altitude Simulators. SAE International. 1-12. https://doi.org/10.4271/2021-01-038811

Dynamic mode decomposition of the acoustic field in radial compressors

[EN] Widely recognized since the beginning of air travel as a major issue, noise reduction remains nowadays a pressing concern for all stakeholders in the aviation industry. While aeroengine compressors, specially at the approach phase, have been historically identified as a leading source of noise, most of the research has been conducted on compressors of the axial type. However, radial compressors are found in a wide array of applications: smaller business jets, helicopters, unmanned aerial vehicles (UAVs), auxiliary power units (APUs), turbochargers for reciprocating engines, etc. Owing to their geometrical particularities, radial compressors feature flow patterns that differ from their axial counterparts, leading to different acoustic performance but also opening the door for different optimization approaches. Yet, classical modal decomposition techniques focused on duct propagation may fail to reveal the complex interactions between geometry and flow features that act as noise sources. In this paper we apply, in addition to the classical approach, a data-driven Dynamic Mode Decomposition (DMD) to pressure data coming from a Detached Eddy Simulation (DES), in which we have experimentally validated the correct reproduction of the modal behaviour of the compressor, thus obtaining in-depth details of the link between flow phenomena and noise generation and transmission across the inlet and outlet ducts. (C) 2019 Elsevier Masson SAS. All rights reserved.The equipment used in this work has been partially supported by the Spanish Ministerio de Economía y Competitividad through grant [DPI2015-70464-R] and by FEDER project funds Dotación de infraestructuras científico técnicas para el Centro Integral de Mejora Energética y Medioambiental de Sistemas de Transporte (CiMeT), [FEDER-ICTS-2012-06] framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economía y Competitividad. F. Roig is supported through the Programa de Apoyo para la Investigación y Desarrollo of the Universitat Politècnica de València [PAID-01-17].Broatch, A.; Garcia Tiscar, J.; Roig-Villanueva, F.; Sharma, S. (2019). Dynamic mode decomposition of the acoustic field in radial compressors. Aerospace Science and Technology. 90:388-400. https://doi.org/10.1016/j.ast.2019.05.015S3884009

Impact of simple surge-enhancing inlet geometries on the acoustic behaviour of a turbocompressor

[EN] This paper reports the results of an experimental campaign where four different inlet geometries for the compressor of an automotive turbocharger were acoustically characterized. These four geometries (a straight pipe for reference, a tapered duct, a 90º elbow and a reservoir) were selected for their potential for deep surge margin enhancement, while being simple enough to be commonly found in production vehicles. A detailed measurement of this surge margin enhancement was performed, together with acoustic measurements of both radiated and orifice noise at design conditions of best isentropic efficiency and also close to the deep surge limit. Results demonstrated that while all the proposed geometries indeed enlarged the usable air mass flow range, changes in the acoustic behaviour of the system could be positive, neutral, or even negative. It is therefore important to carefully consider accurate noise measurements before implementing these geometric solutions in production vehicles, and to further pursue research on the link between the characteristic flow pattern produced by each inlet geometry and the noise emission of the turbocompressor.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The equipment used in this work has been partially supported by FEDER project funds ‘‘Dotacio´n de infraestructuras cientı´fico te´cnicas para el Centro Integral de Mejora Energe´tica y Medioambiental de Sistemas de Transporte (CiMeT)’’ (grant number FEDER-ICTS-2012-06), framed in the operational program of unique scientific and technical infrastructure of the Spanish Government.Broatch, A.; Margot, X.; Garcia Tiscar, J.; Roig-Villanueva, F. (2018). Impact of simple surge-enhancing inlet geometries on the acoustic behaviour of a turbocompressor. International Journal of Engine Research. https://doi.org/10.1177/1468087418784125

Compartir ideas. La Universidad va al Instituto: un proyecto de aprendizaje- servicio transversal de la Universidad de Barcelona

Compartir ideas. La universidad va al instituto es un proyecto de aprendizaje servicio transversal de la Universidad de Barcelona. Este representa una propuesta de aprendizaje servicio que bajo una estructura común permite la participación de estudiantes y profesorado de distintas disciplinas en un mismo proyecto. El aprendizaje servicio (ApS) es una propuesta formativa que permite el desarrollo de diferentes tipos de aprendizajes a partir de la implicación en necesidades sociales reales con la intención de transformarlas (Tapia, 2001; Martínez, 2008; Puig, 2009). En este tipo de proyectos están presentes simultáneamente la intencionalidad pedagógica y la intencionalidad solidaria. Se pueden definir como experiencias educativas solidarias protagonizadas por estudiantes, que tienen como objetivo atender a una necesidad de los destinatarios a la vez que planificar y mejorar la calidad de los aprendizajes (Tapia, 2006)

On the Influence of Inlet Geometry on Turbocharger Compressor Noise

[ES] En la sociedad actual hay cada vez una mayor conciencia de la importancia del calentamiento global. Esta preocupación se ve reflejada por los poderes legislativos de las naciones occidentales en normativas de emisiones cada vez más restrictivas. En este contexto, la industria automovilísitca se ha visto fuertemente incentivada a desarrollar motores térmicos más eficientes e incluso a explorar nuevas soluciones propulsivas, como el motor eléctrico. Para mejorar la eficiencia energética de los motores de combustión interna alternativos se emplea la reducción de los motores. Esto ha obligado a los compresores a trabajar en condiciones, en las que su emisión acústica llega a ser problemática. La revisión bibliográfica llevada a cabo en esta tesis muestra que sigue sin haber consenso acerca de la causa de ciertas componentes del espectro, como los ruidos de banda ancha conocidos cono whoosh y Tip Clearance Noise (TCN). La influencia en el ruido de la geometría de los conductos de entrada al compresor está asimismo poco explorada. Esta tesis presenta una metodología computacional de análisis del campo de flujo que permite la identificación de las estructuras de flujo responsables de las componentes espectrales más relevantes, así como el análisis de la influencia en éstas de las condiciones de operación y las geometrías de entrada. El campo de presión en el interior del compresor se analiza mediante técnicas de descomposición modal. Éstas permiten identificar patrones espaciales y asociarlos a las frecuencias del espectro medido de forma objetiva. Posteriormente se identifica las estructuras de flujo correspondientes a dichos patrones, y su evolución con las condiciones de operación y la geometría de entrada. Mediante la aplicación de la metodología descrita se describe los diferentes mecanismos de generación de los ruidos tonales en el inductor y el borde de fuga del rotor. En cuanto a los ruidos de banda ancha mencionados, los vórtices encontrados aguas arriba del inductor generan oscilaciones en la banda de frecuencias del whoosh, y favorecen el desprendimiento rotativo, que contribuye a dicho ruido en el difusor y la voluta. La carga no estacionaria sobre la superficie de los álabes es identificada como un importante contribuidor al ruido TCN. La influencia de las condiciones de operación en la generación de ruido se manifiesta a través de la intensidad del flujo inverso en el inductor. La aparición de este flujo inverso es característica de los puntos de bajo gasto másico, aunque se sigue apreciando, con menor intensidad, en algunos puntos de alto gasto. El flujo inverso inhibe las condiciones sónicas en el borde de ataque, debilitando el ruido tonal a la frecuencia de paso de álabe. En cuanto a los ruidos de banda ancha, el flujo inverso es la causa de los vórtices en el inductor que producen el ruido whoosh y el despegue rotativo, y además promueve la carga no estacionaria de los álabes, asociada con el TCN. El papel de la geometría del conducto de entrada en el ruido depende de su grado de interacción con los vórtices del inductor. En aquellas geometrías que limitan la extensión aguas arriba de los vórtices del inductor, como los codos con radio de curvatura reducido, tiene lugar una interacción intensa de los vórtices con las paredes del conducto y con otros vórtices. Ello está correlacionado con un aumento del ruido whoosh. Los conductos de entrada que están suficientemente separados de los vórtices, intervienen en el ruido solamente a través de sus propiedades de transmisión de las oscilaciones acústicas generadas en el rotor y el difusor. Al final de la tesis se reflexiona sobre las contribuciones de los resultados expuestos al estado del arte de la investigación en el ruido de compresores. Además, se propone nuevas líneas de investigación para extender la metodología presentada, y completar el conjunto de condiciones de funcionamiento y geometrías de entrada analizadas en este trabajo.[CA] En la societat actual hi ha cada vegada una major consciència de la importància del calfament global. Aquesta preocupació es veu reflectida pels poders legislatius de les nacions occidentals en normatives d'emissions cada vegada més restrictives. En aquest context, la indústria de l'automòbil s'ha vist fortament incentivada a desenvolupar motors tèrmics més eficients i fins i tot a explorar noves solucions propulsives, com el motor elèctric. La tendència adoptada per a millorar l'eficiència energètica dels motors de combustió interna alternatius és la reducció de la grandària dels motors. Això ha obligat els compressors a treballar en condicions més extremes, en les quals la seua emissió acústica arriba a ser problemàtica. La revisió bibliogràfica duta a terme en aquesta tesi mostra que segueix sense haver-hi consens sobre la causa d'unes certes components de l'espectre, com els sorolls de banda ampla coneguts con whoosh i Tip Clearance Noise (TCN). La influència en el soroll de la geometria dels conductes d'entrada al compressor està així mateix poc explorada. Aquesta tesi presenta una metodologia computacional d'anàlisi del camp de flux que permet la identificació de les estructures de flux responsables de les components espectrals més rellevants, així com l'anàlisi de la influència en aquestes de les condicions d'operació i les geometries d'entrada. El camp de pressió a l'interior del compressor s'analitza mitjançant tècniques de descomposició modal. Aquestes permeten identificar patrons espacials i associar-los a les freqüències de l'espectre mesurat de manera objectiva. Posteriorment s'identifica les estructures de flux corresponents a aquests patrons, i la seua evolució amb les condicions d'operació i la geometria d'entrada. Mitjançant l'aplicació de la metodologia descrita es descriu els diferents mecanismes de generació dels sorolls tonals en l'inductor i la vora de fugida del rotor. Quant als sorolls de banda ampla esmentats, els vòrtexs trobats aigües amunt de l'inductor generen oscil·lacions en la banda de freqüències del whoosh, i afavoreixen el despreniment rotatiu, que contribueix a aquest soroll en el difusor i la voluta. La càrrega no estacionària sobre la superfície dels àleps és identificada com un important contribuïdor al soroll TCN. La influència de les condicions d'operació en la generació de soroll es manifesta a través de la intensitat del flux invers en l'inductor. L'aparició d'aquest flux invers és característica dels punts de baixa despesa màssica, encara que es continua apreciant, amb menor intensitat, en alguns punts d'alta despesa. El flux invers inhibeix les condicions sòniques en la vora d'atac, afeblint el soroll tonal a la freqüència de pas d'àlep. Quant als sorolls de banda ampla, el flux invers és la causa dels vòrtexs en l'inductor que produeixen el soroll whoosh i el despreniment rotatiu, i a més promou la càrrega no estacionària dels àleps, associada amb el TCN. El paper de la geometria del conducte d'entrada en el soroll depén del seu grau d'interacció amb els vòrtexs de l'inductor. En aquelles geometries que limiten l'extensió aigües amunt dels vòrtexs de l'inductor, com els colzes amb radi de curvatura reduït, té lloc una interacció intensa dels vòrtexs amb les parets del conducte i amb altres vòrtexs. Això està correlacionat amb un augment del soroll whoosh. Els conductes d'entrada que estan prou separats dels vòrtexs, intervenen en el soroll solament a través de les seues propietats de transmissió de les oscil·lacions acústiques generades en el rotor i el difusor. Al final de la tesi es reflexiona sobre les contribucions dels resultats exposats a l'estat de l'art de la investigació en el soroll de compressors. A més, es proposa noves línies d'investigació per a estendre la metodologia presentada, i completar el conjunt de condicions de funcionament i geometries d'entrada analitzades en aquest treball.[EN] In today's society, there is a growing awareness of the importance of global warming. This concern is reflected by the legislative powers of Western nations in increasingly restrictive emissions regulations. In this context, the automotive industry has been strongly encouraged to develop more efficient thermal engines and even to explore new propulsion solutions, such as the electric motor. The trend adopted to improve the energy efficiency of reciprocating internal combustion engines is the reduction of engine size. This has forced compressors to work in more extreme conditions, where their acoustic emission becomes troublesome. The literature review carried out in this thesis shows that in the last two decades, there has been a great boom of research in the acoustics of radial turbocharger compressors. Despite the progress made, there is still no consensus about the cause of specific spectrum components, such as the broadband noises known as whoosh and Tip Clearance Noise (TCN). The influence of compressor inlet duct geometry on noise is also scarcely explored. This thesis presents a computational methodology of flow field analysis that allows the identification of the flow structures responsible for the most relevant spectral components and the analysis of the influence of operating conditions and inlet geometries on them. The pressure field inside the compressor is analyzed through modal decomposition techniques. These allow identifying spatial patterns and associating them to the frequencies of the measured spectrum in an objective manner. Subsequently, the flow structures corresponding to these patterns are identified, and their evolution with the operating conditions and the inlet geometry is analyzed. Through the application of the described methodology, the different mechanisms of generation of the tonal noises in the inducer and the impeller trailing edge are identified. While the former is related to the sonic conditions at the leading edge, the latter is excited by the asymmetric pressure field in the diffuser. As for the aforementioned broadband noises, the vortices encountered upstream of the inducer generate oscillations in the whoosh frequency band and favor rotating stall, contributing to such noise in the diffuser and volute. Unsteady blade surface loading is identified as an important contributor to TCN noise. The influence of operating conditions on noise generation manifests through the intensity of the backflow in the inducer. The occurrence of backflow is characteristic of low mass flow points, although it is also found, with less intensity, at some higher mass flow points. The backflow inhibits the sonic conditions at the leading edge, weakening the tonal noise at the blade passing frequency. As for broadband noise, reverse flow is the cause of vortices in the inducer that produce whoosh noise and rotating stall. It also promotes the unsteady blade loading associated with TCN. The role of the inlet duct geometry in the noise depends on its degree of interaction with the inducer vortices. In geometries that limit the upstream extent of these vortices, such as low curvature radii elbows, intense interaction of the vortices with the duct walls and other vortices occurs. This is correlated with an increase in whoosh noise. Inlet ducts that are sufficiently separated from the vortices only affect noise through their transmission properties regarding acoustic oscillations generated in the impeller and diffuser. At the end of the thesis, reflections are offered on the contributions of the results to the current knowledge on compressor noise. In addition, new lines of research are proposed to extend the methodology presented and to complete the set of operating conditions and inlet geometries analyzed in this work.Roig Villanueva, F. (2023). On the Influence of Inlet Geometry on Turbocharger Compressor Noise [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19226

Impacto de la geometría de entrada sobre la acústica de turbocompesores de sobrealimentación

Estudio experimental para la caracterización del campo fluido de entrada al turbocompresor con distintas geometrías simples de entrada y su correlación con el impacto sobre el ruido, márgen de bombeo y rendimiento. Se pretende establecer reglas básicas de diseño para conseguir la mejor solución de compromiso teniendo en cuenta los tres factores.Roig Villanueva, F. (2018). Impacto de la geometría de entrada sobre la acústica de turbocompesores de sobrealimentación. http://hdl.handle.net/10251/110663TFG

Estudio CFD del impacto de la relación carrera/diámetro sobre el consumo y emisiones de un motor de automoción

Proyecto confidencial (Riunet)Roig Villanueva, F. (2016). Estudio CFD del impacto de la relación carrera/diámetro sobre el consumo y emisiones de un motor de automoción. http://hdl.handle.net/10251/70080.Archivo delegad

Experimental verification of hydrodynamic similarity in hot flows

[EN] This paper examines a common hypothesis in the design of internal combustion engine exhaust lines, namely that the ratio of the total pressure drop across the line to the inlet dynamic head should be a function only of the Reynolds number. While incompressible flow theory, provided that some simplifications are considered, is often used in support of this hypothesis, detailed experimental verification in actual exhaust lines is absent from the literature. Production exhaust lines contain non-trivial flow complexities such as muffler devices and catalytic converters and, in the case of high-performance engines, often operate at high temperature and high mass flow conditions, thereby rendering the usual theoretical simplifications doubtful. In this work, a production exhaust line composed of cold and hot ends, featuring a muffler and a catalytic converter, is tested at a variety of conditions. Analysis of the results shows that compressibility corrections must be factored in at certain conditions routinely found in actual high-performance engines, and that for hot ends, laminar flow at the converter monolith channels may pose a challenge to the hydrodynamic similarity hypothesis.The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), [FEDER-ICTS-2012-06]" framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economia y Competitividad. F. Roig is supported through the Programa de Apoyo para la Investigation y Desarrollo of the Universitat Politecnica de Valencia [PAID-01-17]Torregrosa, AJ.; Broatch, A.; Garcia Tiscar, J.; Roig-Villanueva, F. (2020). Experimental verification of hydrodynamic similarity in hot flows. Experimental Thermal and Fluid Science. 119:1-6. https://doi.org/10.1016/j.expthermflusci.2020.110220S16119D. Rowley, Exhaust system considerations for 1982 heavy duty trucks, in: SAE Technical Paper, SAE International, 1977. doi:10.4271/770893.D. Deshmukh, J. Modak, K. Nayak, Experimental analysis of backpressure phenomenon consideration for c.i. engine performance improvement, in: SAE Technical Paper, no. 2010-01-1575, SAE International, 2010. doi:10.4271/2010-01-1575.N. Kumar, A. Saroop, A. Kuchhal, V. Chauhan, S. Sharma, Effect of muffler characteristics on performance of a naturally aspirated si engine, in: SAE Technical Paper, no. 2013-01-2834, SAE International, 2013. doi:10.4271/2013-01-2834.T. George, H. Raj, Energy efficient design and modification of an automotive exhaust muffler for optimum noise, transmission loss, insertion loss and back pressure: A review, in: International Conference on Mechanical, Materials and Renew. Energ. doi:10.1088/1757-899X/377/1/012127.Torregrosa, A. J., Broatch, A., Bermúdez, V., & Andrés, I. (2005). Experimental assessment of emission models used for IC engine exhaust noise prediction. Experimental Thermal and Fluid Science, 30(2), 97-107. doi:10.1016/j.expthermflusci.2005.05.001J. Kim, M. Corsetti, L. Biundo, D. Dobson, R. Beason, Modeling and measuring exhaust backpressure resulting from flow restriction through an aftertreatment system, in: SAE Technical Paper, no. 2003-01-0939, SAE International, 2003. doi:10.4271/2003-01-0939.M. Dixit, V. Sundaram, S. Kumar, A novel approach for flow simulation and back pressure prediction of cold end exhaust system, in: SAE Technical Paper, no. 2016-28-0235, SAE International, 2016. doi:10.4271/2016-28-0235.D. Ukrop, M. Shanks, M. Carter, Predicting running vehicle exhaust back pressure in a laboratory using air flowing at room temperature and spreadsheet calculations, in: SAE Technical Paper, no. 2009-01-1154, SAE International, 2009. doi:10.4271/2009-01-1154.F. Payri, A. Torregrosa, A. Broatch, J. Brunel, Pressure loss characterisation of perforated ducts, in: SAE Technical Paper, no. 980282, SAE International, 1998. doi:10.4271/980282. URL https://doi.org/10.4271/980282.Persoons, T., Vanierschot, M., & Van den Bulck, E. (2008). Stereoscopic PIV measurements of swirling flow entering a catalyst substrate. Experimental Thermal and Fluid Science, 32(8), 1590-1596. doi:10.1016/j.expthermflusci.2008.04.011Persoons, T., Vanierschot, M., & Van den Bulck, E. (2008). Oblique inlet pressure loss for swirling flow entering a catalyst substrate. Experimental Thermal and Fluid Science, 32(6), 1222-1231. doi:10.1016/j.expthermflusci.2008.02.002Sutherland, W. (1893). LII. The viscosity of gases and molecular force. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 36(223), 507-531. doi:10.1080/14786449308620508Crane Company. Engineering Division, Flow of fluids through valves, fittings, and pipe, Tech. Rep. TP-410 (1942).Fisher, Control valve handbook, 4th Edition, Emerson Process Management, Marshalltown, Iowa 50158 USA, 2005