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Abstract

The placement of the battery box can have a massive impact on the aerodynamics of an electric vehicle. Although favourable from the viewpoint of vehicle dynamics, an underbody battery box may impair the vehicle aerodynamics. This study aims to quantify the effect of an underbody battery box on the drag force acting on an electric vehicle. Four different variants of the vehicle (original variant, lifted suspension, lifted suspension with an underbody battery box) are investigated by means of computational fluid dynamics. The underbody battery box was found to induce flow separation, resulting in a massive increase in drag force. As a solution, a battery box fairing was designed and tested. The fairing significantly reduced the increase in drag. The results of this study could contribute to the design of more stable and aerodynamically efficient electric vehicles.
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Bibliography

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Authors and Affiliations

Jakub Bobrowski
1
Krzysztof Sobczak
1

  1. Institute of Turbomachinery, Lodz University of Technology, 217/221 Wolczanska, 93-005 Łódz Poland
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Abstract

Steam discharge produces noise due to rapid expansion and a temperature drop of ejected steam. This is why steam silencers are used to change one-stage into multi-stage expansion, which reduces the intensity of pressure and temperature drop during this process and shifts emitted noise into higher frequencies, which are easier to dampen. This paper presents a flow-acoustic numerical model of a steam silencer. It is meant to help to obtain a precise analysis of phenomena occurring in steam silencers and improve the process of designing this type of device. The model described in this paper was based on the parameters of a real working unit manufactured in the Institute of Power Engineering – Thermal Technology Branch. Most of the steam silencers are designed based on construction guidelines that have not been changed for a long time. This restrained an increase in the acoustics efficiency of the steam silencers. An improvement of their flow and acoustic properties allows for the development of smaller, more efficient, and lighter construction. The current version of the model was used for the analysis of flow and acoustic changes which occur after modifying the lower region of a shell of the steam silencer. The proposed modification allowed for a 19% increase in mass flow rate through the silencer and noise reduction in the low-frequency range.
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Bibliography

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[11] Hu X., Zhou Y., Fang J., Man X., Zhao Z.: Computational fluid dynamics research on pressure loss of cross-flow perforated muffler. Chin. J. Mech. Eng. 20(2007), 2, 88–93 (English Edn.).
[12] Tupov V.B., Taratorin A.A.: The choice of turbulence models for steam jet. Procedia Engineer. Dynamic and Vibroacoustics of Machines (DVM2016) 176(2017), 199–206.
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[15] Mohanty A.R, Pattnaik S.P.: An Optimal Design Methodology for a Family of Perforated Mufflers. SAE Tech. Pap. 2005-26-053, 2005.
[16] Zheng S., Kamg Z.X., Lian X.M.: Acoustic Matching Simulation of Muffler with Hybrid Approach. SAE Tech. Pap. 2011-01-1516, 2011.
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Authors and Affiliations

Patryk Gaj
1
Krzysztof Sobczak
2
Joanna Kopania
3
Kamil Wójciak
1

  1. Institute of Power Engineering, Mory 8, 01-330 Warsaw, Poland
  2. Lodz University of Technology, Wólczanska 219, 90-924 Lodz, Poland
  3. Lodz University of Technology, Piotrkowska 266, 90-924 Lodz, Poland
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Abstract

A design of the centrifugal recirculation blower as well as results of its experimental and numerical investigations are presented in this paper. The blower was designed to work in the unique test stand which is used for long-term tests of turbine flowmeters. A 1D method was used to design this blower, then experimental and numerical studies were conducted in order to verify the 1D method. A comparison of the blower pressure increase obtained from the experiment and the computations is presented. Velocity and pressure distributions from the numerical simulations in selected sections are also shown and discussed. Additional numerical studies of a shrouded rotor and a rotor with a lower tip clearance were conducted and are presented in the paper as well.

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Authors and Affiliations

Władysław Kryłłowicz
Michał Kuczkowski
Krzysztof Sobczak
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Abstract

Machines utilising renewable energy constantly undergo research aimed at raising their efficiency. One of them is a Savonius wind turbine, where scientists propose adjustments to improve its aerodynamic properties. At present, their assessment is usually performed by means of transient computational fluid dynamics simulations with two- or threedimensional models. In this paper, the overset (chimera) mesh approach was applied to investigate the performance of a Savonius wind turbine equipped with deformable blades. They were continuously deformed during rotation by a dedicated mechanism to increase a positive torque of the advancing blade, and meanwhile, decrease a negative torque of the returning blade. A quasi-two-dimensional model with a two-way fluid-structure interaction method was applied, where the structural solver determined blade deflection caused by the predefined deformation mechanism and aerodynamic loads, whereas the coupled computational fluid dynamics solver determined the transient flow. The deformable blades rotor performance was calculated and compared with a conventional rigid Savonius turbine, both simulated using the overset mesh approach. The average value of the power coefficient achieved a 55% rise in the case of deformable blades turbine. Additionally, to validate the overset method, its results were compared with the classical sliding mesh method for a conventional rigid rotor.
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Bibliography

[1] Akwa J.V., Vielmo H.A., Petry A.P.: A review on the performance of Savonius wind turbines. Renew. Sust. Energ. Rev. 16(2012), 5, 3054–3064.
[2] Masdari M., Tahani M., Naderi M.H., Babayan N.: Optimization of airfoil Based Savonius wind turbine using coupled discrete vortex method and salp swarm algorithm. J. Clean. Prod. 222(2019), 47–56.
[3] Alom N., Saha U.K..: Influence of blade profiles on Savonius rotor performance: Numerical simulation and experimental validation. Energ. Convers. Manage. 186(2019), 267–277.
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[10] Lipian M., Czapski P., Obidowski D.: Fluid-structure interaction numerical analysis of a small, urban wind turbine blade. Energies 13(2020), 7, 1–15.
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Authors and Affiliations

Emil Marchewka
1
Krzysztof Sobczak
1
Piotr Reorowicz
1
Damian Stanisław Obidowski
1
Krzysztof Jóźwik
1

  1. Lodz University of Technology, Institute of Turbomachinery, Wólczanska 219/223, 90-924 Łódz, Poland

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