Nonlinear Dynamic Behavior of Turbocharger Rotor-Bearing Systems With Hydrodynamic Oil Film and Squeeze Film Damper in Series: Prediction and Experiment

Gjika, Kostandin; Andrés, Luis San; LaRue, Gerry

doi:10.1115/1.4001817

Cited by 28 publications

(21 citation statements)

References 11 publications

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“…The validated nonlinear dynamic behavior model and approach developed and presented by authors in Refs. [27,28] will be updated for this purpose. and acceleration) of the system e = eccentricity ratio 9 = angular location X = real part of eigenvalues ß = fluid viscosity <D = phase difference between different bearings load vectors (compressor side and turbine side) a = imaginary part of eigenvalues Í2 = rotational speed A = load capacity number Subscripts brg = bearing (bearing load) eff = effective (effective speed) ext = extemal (extemal excitation force) J = joumal (joumal speed) L = load (load speed) min, max = minimum, maximum (bearing clearance) r = radial (radial clearance) str = structure (support structure)…”

Section: Closurementioning

confidence: 99%

Turbocharger Synchronous Vibration Control on High Speed Balancer: Test and Prediction

Gjika

Mahadevan

Costeux

2014

Journal of Engineering for Gas Turbines and Power

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Current trends for advanced automotive engines focusing on downsizing, better fuel efficiency, and lower emissions have led to several changes in turbocharger bearing systems design, and technology. Automotive turbochargers are running faster under high engine vibration level. Vibration control is becoming a real critical issue and turbocharger manufacturers are focusing more and more on new and improved balancing technology. This paper deals with turbocharger synchronous vibration control on high speed balancers. In a first step the synchronous rotordynamics behavior is identified. The developed fluid bearing code predicts bearing rotational speed (in case of fully floating design), operating inner and outer bearing film clearances and bearing force coefficients. A rotordynamics code uses this input to predict the synchronous lateral dynamic response of the rotor-bearing system by converging with bearing eccentricity ratio. The rotor-bearing system model is validated by shaft motion test data on high speed balancer (HSB). It shows that only one of the peaks seen on the synchronous G level plot collected in a high speed balancer can be explained by rotordynamics physics. A step-by-step structural dynamics model and analysis validated by experimental frequency response functions provides robust explanations for the other G level peaks.The synchronous vibration response of the system "turbocharger-HSB fixture" is predicted by integrating the predicted rotordynamics rotational bearing loads on the structural dynamics model. Numerous test data show very good correlation with the prediction, which validates the developed analytical model. The "rotordynamics-structural dynamics model" allows deep understanding of turbocharger synchronous vibration control, as well as optimization of the high speed balancer tooling.

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Section: Closurementioning

confidence: 99%

Turbocharger Synchronous Vibration Control on High Speed Balancer: Test and Prediction

Gjika

Mahadevan

Costeux

2014

Journal of Engineering for Gas Turbines and Power

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“…The energy transport equation is (10) Here, h* = ah^ is the liquid film thickness, which is a fraction (a) of the actual gap separating the rotating shaft from the ring surface.…”

Section: Fig 3 Kinematics Of Journai and Ring Centers And Notation Fmentioning

confidence: 99%

“…The lumped parameter thermal model [7] efficiently served to automate and qualify the design of the bearing systems in a reduced amount of time and with a lower testing effort [10]. In addition, the code's output (predictions), when used in conjunction with a nonlinear rotordynamics tool, generate the shaft motion maps that quantify the appearance and persistence of subsynchronous whirl motions, whose amplitude and frequency are evaluated in order to determine the reliability of modem TC systems.…”

Section: Introductionmentioning

confidence: 99%

On the Effect of Thermal Energy Transport to the Performance of (Semi) Floating Ring Bearing Systems for Automotive Turbochargers

Andrés

Barbarie

Bhattacharya

et al. 2012

Journal of Engineering for Gas Turbines and Power

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Bearing systems in engine-oil lubricated turbochargers (TCs) must operate reliably over a wide range of shaft speeds and withstand severe axial and radial thermal gradients. An engineered thermal management of the energy flows into and out of the bearing system is paramount in order to ensure the component's mechanical integrity and the robustness of the bearing system. The bearings, radial and thrust type, act both as a load bearing and low friction support with the lubricant carrying away a large fraction of the thermal energy generated by rotational drag and the heat flow disposed from a hot shaft. The paper introduces a thermohydrodynamic analysis for the prediction of the pressure and temperature fields in a (semi) floating ring bearing (S)ERB system. The analysis simultaneously solves the Reynolds equation with variable oil viscosity and the thermal energy transport equation in the inner and outer fllms of the bearing system. Elow conditions in both fllms are coupled to the temperature distribution and heat flow through the (semi) floating ring. Other constraints include calculating the fluid fllms' forces reacting to the externally applied load and to determine the operating journal and ring eccentricities. The predictions of performance for a unique realistic (S)ERB configuration at typical TC operating conditions reveal a distinct knowledge: (a) the heat flow from the shaft into the inner fllm is overwhelming, in particular, at the inlet lubricant plane where the temperature difference with the cold oil is largest; (b) the inner fllm temperature quickly increases as soon as the (cold) lubricant enters the film and is due to the large amount of energy generated by shear drag and the heat transfer fl-om the shaft;(c) a floating ring develops a significant radial temperature gradient; (d) at all shaft speeds, low and high, the thermal energy carried away by the lubricant streams is no less than 70% of the total energy input; the rest is conducted through the TC casing. To warrant this thermal energy distribution, enough lubricant flow must be supplied to the bearing system. The efficient computational model offers a distinct advantage over existing lumped parameters thermal models and there is no penalty in the execution time.

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“…Many researchers have proven the advantages of the nonlinear method in turbocharger dynamic performance prediction, including the limit cycle amplitude and the frequencies of subsynchronous whirls [2,5,9] . SAN ANDRÉS has done many outstanding researches in rotor-bearings system of turbochargers.…”

Section: Introduction mentioning

confidence: 99%

Effects of semi-floating ring bearing outer clearance on the subsynchronous oscillation of turbocharger rotor

Liang

Zhou

2016

Chin. J. Mech. Eng.

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Semi-floating ring bearing(SFRB) is developed to control the vibration of turbocharger rotor. The outer clearance of SFRB affects the magnitude and frequency of nonlinear whirl motion, which is significant for the design of turbocharger. In order to explore the effects of outer clearance, a transient finite element analysis program for rotor and oil film bearing is built and validated by a published experimental case. The nonlinear dynamic behaviors of rotor-SFRB system are simulated. According to the simulation results, two representative subsynchronous oscillations excited by the two bearings respectively are discovered. As the outer clearance of SFRB increases from 24 μm to 60 μm, the low-frequency subsynchronous oscillation experiences three steps, including a strong start, a gradual recession and a combination with the other one. At the same time, the high-frequency subsynchronous oscillation starts to appear gradually, then strengthens, and finally combines. If gravity and unbalance are neglected, the combination will start starts from high rotor speed and extents to low rotor speed, just like a "zipper". It is found from the quantitative analysis that when the outer clearance increases, the vibration amplitude experiences large value firstly, then reduction, and suddenly increasing after combination. A useful design principle of SFRB outer clearance for minimum vibration amplitude is proposed: the outer clearance value should be chosen to keep the frequency of two subsynchronous oscillations clearly separated and their amplitudes close.

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Nonlinear Dynamic Behavior of Turbocharger Rotor-Bearing Systems With Hydrodynamic Oil Film and Squeeze Film Damper in Series: Prediction and Experiment

Cited by 28 publications

References 11 publications

Turbocharger Synchronous Vibration Control on High Speed Balancer: Test and Prediction

Turbocharger Synchronous Vibration Control on High Speed Balancer: Test and Prediction

On the Effect of Thermal Energy Transport to the Performance of (Semi) Floating Ring Bearing Systems for Automotive Turbochargers

Effects of semi-floating ring bearing outer clearance on the subsynchronous oscillation of turbocharger rotor

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