Analysis of Gas-Lubricated Bearings with a Coupled Boundary Effect for Micro Gas Turbine

The increasing number of passenger cars worldwide and the consequent increasing rate of global oil consumption have raised the attention on fuel prices and have caused serious problems to the environment. Nowadays, the demand for reducing fuel consumption and pollutant emissions has paved the way to the development of more efficient power generation systems for the transportation sector. The lower fuel burning and pollutant emissions of hybrid electric vehicles give a strong motivation and encourage further investigations in this field. This research aims to investigate novel configurations, which could achieve further performance benefits for vehicle powertrain. Automakers claim that the employment of a gas turbine operating as range extender in a series hybrid configuration is the most efficiency solution in the coming years. In particular, a Micro Gas Turbine (MGT) can be considered as an alternative to the internal combustion engine (ICE) as a range extender for electric vehicles. The MGT produces less raw exhaust gaseous emissions such as HC and CO and static applications compared to the ICE. In addition, the MGT weight is lower than an equivalent ICE and potentially can reduce the level of CO2 especially in a vehicle application. This study presents a parametric study of MGT applications for Range-Extended Electric Vehicle (REEV). The main objective is to examine the MGT performance to meet the requirements for a REEV that could become competitive, in terms of fuel consumption and pollutant emissions, to equivalent diesel or gasoline hybrid propulsion units or to conventional diesel vehicle.

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“…4) and the angular acceleration force results the tractive effort at each time step (Eq. 5) [22][23][24][25].…”

Section: Powertrain Modelingmentioning

confidence: 99%

Application of Micro Gas Turbine in Range-Extended Electric Vehicles

Karvountzis-Kontakiotis

Andwari

Pesyridis

et al. 2018

Energy

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“…Static [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and dynamic [12,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] performances of conventional rigid bore aerodynamic journal bearings have been explored by many researchers in the past from various investigation perspectives. Thermal effects, influence of inertia force, rarefication and turbulence on the static performances have been explored and presented by the authors [4,5,11].…”

Section: Introductionmentioning

confidence: 99%

Effects of new micro-pocketed bore surface topographies on the performance behaviours of aerodynamic journal bearing

Pattnayak¹,

Pandey²,

Dutt³

2021

Surf. Topogr.: Metrol. Prop.

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This paper presents the exploration for improving the static and dynamic performance behaviours of a self-acting rigid gas journal bearing employing some new conceived micro-depth pocketed surface topographies at the bore. The conceived micro-pockets comprise of relatively large size rectangular pocket having micro-depth at bearing bore in the converging zone followed by placing of different designs of sub-pockets at the trailing edge of the previous one in the direction of journal rotation. The form of equation achieved from Patir and Cheng’s model for the case of hydrodynamic lubrication regime and the related dynamic pressure equations have been solved using the finite volume method discretisation scheme followed by the solution of the algebraic equations using the Gauss-Seidel iterative method. The minimum film thickness, frictional force, side leakage, bearing dynamic coefficients, effective stiffness, effective damping, and critical mass parameters have been investigated with each new bore surface topography and compared with the performances of conventional aerodynamic journal bearing. Substantial improvements in both static and dynamic performances have been found with the new micro-pocketed bore surface topographies as compared to conventional one. Moreover, the established best bore design has produced significant increase (21%) in minimum film thickness, substantial reduction (12%) in coefficient of friction, and excellent improvement (170%) in the stability parameter (critical mass) as compared to the conventional case.

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“…Aerodynamic microbearings are widely used owing to their advantages of simple structure, low friction resistance, no contamination and minimal temperature limitation in comparison with the oil-lubricated bearings and electromagnetic bearings [4][5][6][7]. In these microfluidic applications, the lubricating films between the journals and bearing pads usually become very small and are found to be even smaller than the molecular mean free path [8,9], and the continuum flow of Reynolds equation is no longer valid for describing the rarefied gas flow characteristics. Thus the effect of gas rarefaction must be taken into consideration.…”

Section: Introductionmentioning

confidence: 99%

Research on Static and Dynamic Characteristics of Gas-lubricated Microbearings for Microfluidic Devices

Liu

2020

Applied Sciences

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Aerodynamic journal microbearings with microtribological phenomena significantly influence the operating stability of microfluidic devices. The modified Reynolds equations including different rarefaction models are derived and are solved by the partial derivative method and relaxation iteration algorithm. The effects of Knudsen number and bearing parameters on the static and dynamic characteristics of microbearings are investigated in detail. The results show that the rarefaction effect plays a crucial role in the ultra-thin gas film lubrication. The maximum film pressure of Fukui–Kaneko (FK) model is lowest and the result in Boltzmann model is largest in small Knudsen number regions. As the Knudsen number increases further, the curve of FK model is coincident with that of the Boltzmann model in the transition regime. The direct stiffness coefficients of Boltzmann model increase with the increase of eccentricity ratio and aspect ratio, whereas the effect of Knudsen number on the damping coefficients yields a relatively complicated trend.

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Analysis of Gas-Lubricated Bearings with a Coupled Boundary Effect for Micro Gas Turbine

Cited by 12 publications

References 3 publications

Application of Micro Gas Turbine in Range-Extended Electric Vehicles

Application of Micro Gas Turbine in Range-Extended Electric Vehicles

Effects of new micro-pocketed bore surface topographies on the performance behaviours of aerodynamic journal bearing

Research on Static and Dynamic Characteristics of Gas-lubricated Microbearings for Microfluidic Devices

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