Comparison Between Steady and Unsteady Double-Entry Turbine Performance Using the Quasi-Steady Assumption

Copeland, Colin; Martinez-Botas, Ricardo; Seiler, Martin

doi:10.1115/gt2009-59290

Cited by 24 publications

(17 citation statements)

References 13 publications

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“…[6][7][8][9] Nevertheless, most of the current turbocharger designs including VGT are still based on steady-state assumptions. This is mainly because of the fact that a turbine's unsteady performance is still not completely understood especially on the question of defining the instantaneous efficiency.…”

Section: Introductionmentioning

confidence: 99%

Novel method to improve engine exhaust energy extraction with active control turbocharger

Rajoo

Pesiridis

Martinez-Botas

2013

International Journal of Engine Research

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A mixed-flow turbine with pivoting nozzle vanes was designed and tested to actively adapt to the pulsating exhaust flow (called the active control turbocharger). The turbine was tested at an equivalent speed of 48,000 r/min with inlet flow pulsation of 40 and 60 Hz, which corresponds to a four-stroke diesel engine speed of 1600 and 2400 r/min, respectively. The nozzle vane operating schedules for each pulse period are evaluated experimentally in two general modes: natural opening and closing of the vanes due to the pulsating flow and the forced sinusoidal oscillation of the vanes to match the incoming pulsating flow. The turbine energy extraction as well as efficiency is compared for the two modes to formulate its effectiveness. In addition, a one-dimensional commercial code was implemented, matching an active control turbocharger to an engine with equivalent characteristics to the one simulated in the laboratory. The results obtained represented an improvement over the experimental data with the engine power increasing by between 3.58% and 7.76% between 800 and 1400 r/min; the actual turbocharger power recovery required to achieve this increase in engine power was far higher and typically exceeded 20% throughout the lower half of the engine speed range while remaining higher than 10% for most of the rest. The aim of this article is to demonstrate the potential of active control turbocharger in relation to current turbocharging practice. It has shown strong potentials to improve engine performance in parts of the operational envelope, which need to be further harnessed for real-life applications.

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Section: Introductionmentioning

confidence: 99%

Novel method to improve engine exhaust energy extraction with active control turbocharger

Rajoo

Pesiridis

Martinez-Botas

2013

International Journal of Engine Research

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“…The turbine is attached to a 60kW eddy current dynamometer originally developed by Szymko [8]. The reaction force on the dynamometer assembly is measured by a 20kg load cell on the gimbal-mounted dynamometer housing.…”

Section: Experimental Methodologymentioning

confidence: 99%

Comparison of Flow Field Between Steady and Unsteady Flow of an Automotive Mixed Flow Turbocharger Turbine

2016

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Graphical abstract AbstractGlobal decarbonizing efforts in transportation industry have forced the automotive manufacturers to opt for highly downsized high power-to-weight ratio engines. Since its invention, turbocharger remains as integral element in order to achieve this target. However, although it has been proven that a turbocharger turbine works in highly pulsatile environment, it is still designed under steady state assumption. This is due to the lack of understanding on the nature of pulsating flow field within the turbocharger turbine stage. This paper presents an effort to visualize the pulsating flow feature using experimentally validated Computational Fluid Dynamics (CFD) simulations. For this purpose, a lean-vaned mixed-flow turbine with rotational speed of 30000 rpm at 20 Hz flow frequency, which represent turbine operation for 3-cylinder 4-stroke engine operating at 800 rpm has been used. Results indicated that the introduction of pulsating flow has resulted in more irregular pattern of flow field as compared to steady flow operation. It has also been indicated that the flow behaves very differently between pressure increment and decrement instances. During the pressure decrement instance, flow blockage in terms of low pressure region occupies most of the turbine passage as the flow exit the turbine.Keywords : Mixed-flow turbine, computational fluid dynamics, pulsating flow AbstrakUsaha mengurangkan pelepasan karbon secara global dalam industry pengangkutan telah menjadikan pengeluar kenderaan automotif memilih untuk menghasilkan enjin yang mempunyai nisbah kuasa-kepada-berat yang tinggi. Sejak penciptaannya, pengecas turbo masih kekal menjadi elemen penting untuk mencapai matlamat ini. Namun begitu, sungguhpun telah dibuktikan bahawa alat ini sentiasa beroperasi dalam keadaan aliran berdenyut, ianya masih lagi direka menggunakan andaian aliran mantap. Ini adalah kerana kurangnya kefahaman terhadap persekitaran aliran denyutan dalam pengecas turbo tersebut. Kertas kerja ini membentangkan satu usaha untuk memaparkan ciri-ciri aliran denyut menggunakan kaedah Pengiraan Dinamik Bendalir (CFD) yang telah disahkan secara uji kaji. Untuk tujuan ini, turbin aliran campuran dengan kelajuan putaran 30000 rpm pada frekuensi aliran 20 Hz, bagi mewakili operasi turbin pada enjin 3-silindir 4 lejang yang beroperasi pada 800 rpm telah digunakan. Keputusan menunjukkan bahawa pengenalan aliran berdenyut telah menyebabkan corak aliran yang lebih tidak teratur berbanding operasi aliran mantap. Keputusan juga telah menunjukkan bahawa corak aliran adalah sangat berbeza antara sewaktu tekanan sedang menaik dan menurun. Semasa tekanan sedang menurun, aliran didapati terganggudi mana kawasan tekanan rendah telahmeliputi sebahagian besar laluan turbin semasa aliran hamper dengan bahagian keluaran turbin.Kata kunci: Turbin aliran campuran, dinamik bendalir berbantukan komputer,

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“…Experimental investigations developed on specialized test facilities can help to obtain a better understanding of the steady flow behaviour and the unsteady flow behaviour of the turbine, even if some difficulties related to measurement of the instantaneous parameters need to be overcome, referring both to the measuring equipment and to the postprocessing methodologies. 12,13 As is well known, the engine-turbocharger matching can be successfully carried out by means of onedimensional (1D) models. The classical quasi-steadystate approach, based on the compressor and turbine characteristic maps (provided by the manufacturers or directly measured), is usually followed.…”

Section: Introductionmentioning

confidence: 99%

One-dimensional simulations and experimental analysis of a wastegated turbine for automotive engines under unsteady flow conditions

Bellis

Marelli

2015

Proceedings of the Institution of Mechanical Engineers, Part D:

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In the paper, the unsteady behaviour of a turbocharger waste-gated turbine (IHI-RHF3) is investigated following both an experimental and numerical approach. First, an experimental campaign is performed in a specialized test rig operating at the University of Genoa, for different openings of the waste-gate valve and under steady and unsteady flow operations. A proper configuration of the turbine outlet circuit fitted with a separating wall is used to carry out instantaneous measurements downstream the turbine wheel and the waste-gate valve.\ud The above data constitute the basis for the tuning and validation of a 1D turbine model, recently developed at the University of Naples. The procedure geometrically schematizes the entire turbine, starting from few linear and angular dimensions directly measured on the hardware. A preliminary model tuning is carried out on the basis of the characteristic map measured for a completely closed waste-gate valve under steady flow operations.\ud Then, a refined 1D schematization of the experimental apparatus is implemented within the commercial GT-Power® software, including the turbine, the waste-gate circuit and the upstream and downstream measuring stations. In particular, the classical map-based approach is suitably corrected with a sequence of pipes that schematizes each component of the turbine (inlet/outlet ducts, volute and wheel) to account for the wave propagation and storage phenomena inside the machine. A detailed 1D schematization of the waste-gate circuit is also implemented and independently tuned.\ud Finally, the turbine model capability under unsteady flow conditions is tested for different waste-gate openings and pulse frequencies, by applying time-dependent boundary conditions. In particular, the upstream and downstream measured pressure and temperature are imposed at the model ends, and the instantaneous mass flow rate and actual power are numerically evaluated. The results are compared with the experimental data, denoting a good accuracy, and showing some improvements with the respect to the standard turbine modelling in the case of the mass flow rate prediction. On the contrary, the computed actual power shows some inaccuracies, especially at higher pulse frequencies

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Comparison Between Steady and Unsteady Double-Entry Turbine Performance Using the Quasi-Steady Assumption

Cited by 24 publications

References 13 publications

Novel method to improve engine exhaust energy extraction with active control turbocharger

Novel method to improve engine exhaust energy extraction with active control turbocharger

Comparison of Flow Field Between Steady and Unsteady Flow of an Automotive Mixed Flow Turbocharger Turbine

One-dimensional simulations and experimental analysis of a wastegated turbine for automotive engines under unsteady flow conditions

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