Axial Turbine Turbocharger for Charging a Lean-Burn Gasoline Engine

Sagan, Lukas; Kuestner, Christoph; Eilts, Peter; Seume, Joerg R.

doi:10.4271/2022-01-0377

Cited by 3 publications

References 31 publications

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Experimental and numerical analysis of a waste-gated turbine for automotive turbocharged engine

Cordalonga,

Usai,

Marelli

2024

J. Phys.: Conf. Ser.

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This work presents the results of an experimental campaign focused on the steady state behaviour of a waste-gated turbocharger turbine for spark ignition engine. In a first step, the turbine behaviour under different openings of the waste-gate valve is analysed through an experimental campaign performed at the test rig for components of propulsion systems of the University of Genoa. Based on this experimental activity, a specific numerical model is developed to study the interaction between the rotor channel and the waste-gate valve. A 1D schematization of the experimental test rig is implemented within the commercial GT-Power code, including the turbine, the waste-gate valve, and the upstream and downstream circuits. In the turbine schematization, the “wheel-map”, estimated by means of the 1D software, is utilized. A preliminary tuning is carried out based on the turbine characteristic map measured with the waste-gate valve in the fully closed position. Then, the influence of various positions of the by-pass valve on the definition of turbine characteristic curves is investigated under steady flow condition. A refined model of the waste-gate system reveals to be necessary to correctly reproduce the swallowing capacity of the by-pass port. The waste-gate model is tuned against the experimental findings for a completely closed turbine wheel and various settings of the waste-gate valve. Finally, once the 1D models of the turbine and of the waste-gate system are independently tuned, their behaviour under parallel flow is analysed. The proposed numerical and experimental results demonstrate the mutual interaction of the two components. In addition, it is highlighted that the turbine and the waste-gate circuit cannot be considered as two systems working in parallel under the same pressure ratio, as usually assumed in 1D codes.

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Experimental and numerical analysis of a waste-gated turbine for automotive turbocharged engine

Cordalonga,

Usai,

Marelli

2024

J. Phys.: Conf. Ser.

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Axial Turbine Turbocharger for Charging a Lean-Burn Gasoline Engine

Sagan¹,

Kuestner²,

Eilts³

et al. 2022

SAE Int. J. Adv. & Curr. Prac. in Mobility

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<div class="section abstract"><div class="htmlview paragraph">A single-stage turbocharger turbine is developed with the objective of enabling a gasoline spark-ignition engine to operate under lean-burn conditions with an air-to-fuel ratio of <b><i>λ</i></b>=2 in the range of the Worldwide Harmonized Light-Duty Vehicles Test Cycle. For this purpose, extensive 1-D engine simulations are performed using a combination of a simple compressor and simple turbine model as well as a combination of the stock compressor and a simple turbine model. The results show that an isentropic turbine efficiency of more than 70% over a wide operating range is required for the desired engine operation - especially with regard to the low-end-torque. Based on the crank-angle-resolved engine simulation data, turbine requirements are determined. Their evaluation shows that an axial turbine is a reasonable alternative to conventional radial turbines for this application. Next, a preliminary axial turbine is designed using 1-D/2-D design approaches. Then, the corresponding performance map is calculated by 3-D CFD simulations showing isentropic total-to-static turbine efficiencies of up to 77% over a wide operating range. Ultimately, the derived turbine performance map is implemented into the 1-D engine model and the valve train settings are optimized for this configuration to enhance the lean-burn performance further. The simulation results show a significantly extended <i>λ</i>=2 operating range in comparison to the stock turbine.</div></div>

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Increasing Engine Efficiency with Hydrogen Assisted Lean Burn Operation on a Small Bore, Long Stroke DISI Engine

Wenz¹,

Eilts²

2023

SAE Technical Paper Series

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<div class="section abstract"><div class="htmlview paragraph">Internal combustion engines fall under increased environmental and social pressure. However, they will still play an important role in future transport, especially in hybrid propulsion systems. As a consequence, efficiency of SI engines has to be further increased. Lean burn operation provides a promising way to reach this target.</div><div class="htmlview paragraph">An extremely downsized SI single cylinder research engine is used for the investigations. The engine features a stroke-to-bore ratio of 1.5, leading to higher piston speeds and hence increased tumble motion. The resulting increase in turbulent flame speed supports sufficient combustion performance of diluted mixtures. Although the mentioned provisions increase combustion stability for lean burn operation the reachable relative air/fuel ratio is limited. In order to extend the lean burn capabilities of the engine (λ ≥ 2.0) and further exploit the efficiency advantages of this combustion process the engine is upgraded with a hydrogen port fuel injection. With its high laminar flame speeds and low demanded ignition energy, hydrogen acts as a good combustion enhancer in order to achieve the aforementioned targets.</div><div class="htmlview paragraph">The conducted measurements show that small amounts of hydrogen are sufficient to reach relative air/fuel ratios of λ ≥ 2.0 for all investigated operating points. The increase in lean burn operation is accompanied by an increase of the indicated efficiency. The investigations reveal furthermore that efficiency does not peak with the highest reachable relative air/fuel ratio. This results in the highest achieved indicated efficiency of η<sub>i</sub> = 45.6% at a relative air/fuel ratio of λ = 1.9.</div></div>

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Axial Turbine Turbocharger for Charging a Lean-Burn Gasoline Engine

Cited by 3 publications

References 31 publications

Experimental and numerical analysis of a waste-gated turbine for automotive turbocharged engine

Experimental and numerical analysis of a waste-gated turbine for automotive turbocharged engine

Axial Turbine Turbocharger for Charging a Lean-Burn Gasoline Engine

Increasing Engine Efficiency with Hydrogen Assisted Lean Burn Operation on a Small Bore, Long Stroke DISI Engine

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