Steady and Unsteady Velocity Measurements in a Small Turbocharger Turbine with Computational Validation

Karamanis, N.; Palfreyman, D.; Arcoumanis, C.; Martinez-Botas, Ricardo

doi:10.1088/1742-6596/45/1/023

Cited by 6 publications

(3 citation statements)

References 0 publications

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“…Karamanis et. al [26] shows that 3-D CFD flow field analysis has a significant agreement with the experimental measurements if a refined meshing is used. The refined meshing CFD is usually carried out on a high capability computer.…”

Section: Computational Fluid Dynamics (Cfd)mentioning

confidence: 91%

Design methodology of a low pressure turbine for waste heat recovery via electric turbocompounding

Mamat

Martinez-Botas

Rajoo

et al. 2016

Applied Thermal Engineering

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This paper presents a design methodology of a high performance Low Pressure Turbine (LPT) for turbocompounding applications to be used in a 1.0 L “cost-effective, ultra-efficient heavily downsized gasoline engine for a small and large segment passenger car”. Under this assumption, the LPT was designed to recover the latent energy of discharged exhaust gases at low pressure ratios (1.05–1.3) and to drive a small electric generator with a maximum power output of 1.0 kW. The design speed was fixed at 50,000 rpm with a pressure ratio, PR of 1.08. Commercially available turbines are not suitable for this purpose due to the very low efficiencies experienced when operating in these pressure ratio ranges. By fixing all the LPT requirements, the turbine loss model was combined with the geometrical model to calculate preliminary LPT geometry. The LPT features a mixed-flow turbine with a cone angle of 40° and 9 blades, with an inlet blade angle at radius mean square of +20°. The exit-to-inlet area ratio value is approximately 0.372 which is outside of the conventional range indicating the novelty of the approach. A single passage Computational Fluid Dynamics (CFD) model was applied to optimize the preliminary LPT design by changing the inlet absolute angle. The investigation found the optimal inlet absolute angle was 77°. Turbine off-design performance was then predicted from single passage CFD model. A rapid prototype of the LPT was manufactured and tested in Imperial College turbocharger testing facility under steady-state and pulsating flow. The steady-state testing was conducted over speed parameter ranges from 1206 rpm/K0.5 to 1809 rpm/K0.5. The test results showed a typical flow capacity trend as a conventional radial turbine but the LPT had higher total-to-static efficiency, ηt-s in the lower pressure ratio regions. A maximum total-to-static efficiency, ηt-s of 0.758 at pressure ratio, PR ≈ 1.1 was found, no available turbines exist in this range as parameters. A validation of the predicted single passage CFD analysis for the off-design performance against the LPT test result found a minimum total-to-static efficiency Standard Deviation of ±0.026 points for the speed parameter of 1507 rpm/K0.5. A minimum Mass Flow Parameter Standard Deviation of ±0.091 kg/s K0.5 bar is found at 1206 rpm/K0.5

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Section: Computational Fluid Dynamics (Cfd)mentioning

confidence: 91%

Design methodology of a low pressure turbine for waste heat recovery via electric turbocompounding

Mamat

Martinez-Botas

Rajoo

et al. 2016

Applied Thermal Engineering

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“…In this section a description of the design procedure followed to develop the low pressure turbine under study is presented. For reasons of space, only a general overview of the entire process is provided here but, for an extensive and more detailed analysis, the reader can refer to previously published work by the authors [15]. The operating conditions which were taken as reference for the turbine design are given in Table 1.…”

Section: Low Pressure Turbine Designmentioning

confidence: 99%

“…This is one of the main advantages of a mixed-flow turbine in respect to the radial counterpart [23] and one of the reasons why it was decided to develop the low pressure turbine as a mixed-flow turbine. After set up the main geometric features of the newly designed turbine, an exhaustive 3-D and CFD analysis was carried out [15] by using a 3-D Solidwork and Ansys CFX, respectively. The final outcome of the turbine design is shown in Figure 2.…”

Section: Low Pressure Turbine Designmentioning

confidence: 99%

Design and Development of a Low Pressure Turbine for Turbocompounding Applications

Mamat

Romagnoli

Martinez-Botas³

2012

JGPP

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This paper describes the development of a high performance low pressure turbine (LPT) for turbocompounding applications to be used in a 1.0 litre "cost-effective, ultra-efficient gasoline engine for a small and large segment passenger car". Under this assumption, a mixed-flow turbine was designed to recover latent energy of discharged exhaust gases at low pressure ratios (1.05-1.3) and to drive a small electric generator with a maximum power output of 1.0 kW. The design operating conditions were fixed at 50,000 rpm with a pressure ratio of 1.1. Commercially available turbines are not suitable for this purpose due to the very low efficiencies experienced when operating in these pressure ratio ranges. The low pressure turbine performance was simulated using a commercial CFD software. Then, turbine performance was validated with a comprehensive turbine testing that was accomplished by using the Imperial College turbine test rig. The testing and the simulation conditions were conducted for a range of design equivalent speeds spanning between 80% and 120% at steps of 10% increase. In addition, the impact of the turbocompounding on Brake Specific Fuel Consumption (BSFC) and Brake Mean Effective Pressure (BMEP) was also assessed by using a 1-D validated engine model of the engine under study. Three different arrangements for the turbocompounding were assessed: (1) precatalyst, (2) post-catalyst and (3) in the wastegate of the main turbocharger. The outcomes of the simulation were compared to those obtained for the baseline engine and are discussed in the the paper. The 1-D engine simulation had shown that the maximum benefit of the turbocompounding can be achieved when it was located at the post catalyst with maximum BSFC reduction of 2.4% at 1500 rpm and 3.0% of BMEP increase at 1000rpm.

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Pressure Distribution on the Blade Surface of an Automotive Mixed Flow Turbocharger Turbine Under Pulsating Flow Conditions

2016

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The increment of the contribution to CO2 release by transportation industry as other sectors are decarbonizing is evident. As number of world population continue to increase, the task of developing highly downsized high power-to-weight ratio engines are critical. Over more than a hundred years of invention, turbocharger remains a key technology that enable highly boosted efficient engine. Despite its actual operating environment which is pulsating flow, the turbocharger turbine that is available to date is still designed and assessed under the assumption of steady flow conditions. This is attributable to the lack of understanding on the insight of the flow field effect towards the torque generation of the turbine blade under pulsating flow conditions. This paper presents an effort towards investigating the influence of pulsating flow on the blade loading and its differences from steady state conditions through the use of Computational Fluid Dynamics (CFD). 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 presented in terms of spanwise location of the blade indicated different behavior at each location. Close to the hub, there are strong flow separation that hinders torque generation is seen while at mid-span more torque is generated under unsteady flow as compared to its steady counterpart. Moreover, close to the shroud, the pressure difference between steady and pulsating flow is almost identical

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Steady and Unsteady Velocity Measurements in a Small Turbocharger Turbine with Computational Validation

Cited by 6 publications

References 0 publications

Design methodology of a low pressure turbine for waste heat recovery via electric turbocompounding

Design methodology of a low pressure turbine for waste heat recovery via electric turbocompounding

Design and Development of a Low Pressure Turbine for Turbocompounding Applications

Pressure Distribution on the Blade Surface of an Automotive Mixed Flow Turbocharger Turbine Under Pulsating Flow Conditions

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