Estimation Methodology for Automotive Turbochargers Speed Fluctuations due to Pulsating Flows

2014 ◽  
Author(s):  
F. Ponti ◽  
V. Ravaglioli ◽  
M. De Cesare
Keyword(s):  
Rotational Speed ◽  
Estimation Algorithm ◽  
Mean Value ◽  
Operating Conditions ◽  
Passenger Cars ◽  
Flow Maps ◽  
Lack Of Information ◽  
Speed Fluctuation ◽  
Small Engines ◽  
Speed Fluctuations

Turbocharging technique, together with engine downsizing, will play a fundamental role in the near future as a way to reach the required maximum performance while reducing engine displacement and, consequently, CO2 emissions. However, performing an optimal control of the turbocharging system is very difficult, especially for small engines fitted with a low number of cylinders. This is mainly due to the high turbocharger operating range and to the fact that the flow through compressor and turbine is highly unsteady, while only steady flow maps are usually provided by the manufacturer. In addition, in passenger cars applications, it is usually difficult to optimize turbocharger operating conditions because of the lack of information about pressure/temperature in turbine upstream/downstream circuits and turbocharger rotational speed. This work presents a methodology suitable for instantaneous turbocharger rotational speed determination through a proper processing of the signal coming from an accelerometer mounted on the compressor diffuser or a microphone faced to the compressor. The presented approach can be used to evaluate turbocharger speed mean value and turbocharger speed fluctuation (due to unsteady flow in turbine upstream and downstream circuits), that can be correlated to the power delivered by the turbine. The whole estimation algorithm has been developed and validated for a light duty turbocharged Common-Rail Diesel engine mounted in a test cell. Nevertheless, the developed methodology is general and can be applied to different turbochargers, both for Spark Ignited and Diesel applications.

Estimation Methodology for Automotive Turbochargers Speed Fluctuations Due to Pulsating Flows

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Fabrizio Ponti ◽  
Vittorio Ravaglioli ◽  
Matteo De Cesare
Keyword(s):  
Rotational Speed ◽  
Estimation Algorithm ◽  
Mean Value ◽  
Operating Conditions ◽  
Passenger Cars ◽  
Flow Maps ◽  
Lack Of Information ◽  
Speed Fluctuation ◽  
Small Engines ◽  
Speed Fluctuations

Turbocharging technique, together with engine downsizing, will play a fundamental role in the near future as a way to reach the required maximum performance while reducing engine displacement and, consequently, CO2 emissions. However, performing an optimal control of the turbocharging system is very difficult, especially for small engines fitted with a low number of cylinders. This is mainly due to the high turbocharger operating range and to the fact that the flow through compressor and turbine is highly unsteady, while only steady-flow maps are usually provided by the manufacturer. In addition, in passenger cars applications, it is usually difficult to optimize turbocharger operating conditions because of the lack of information about pressure/temperature in turbine upstream/downstream circuits and turbocharger rotational speed. This work presents a methodology suitable for instantaneous turbocharger rotational speed determination through a proper processing of the signal coming from an accelerometer mounted on the compressor diffuser or a microphone faced to the compressor. The presented approach can be used to evaluate turbocharger speed mean value and turbocharger speed fluctuation (due to unsteady flow in turbine upstream and downstream circuits), which can be correlated to the power delivered by the turbine. The whole estimation algorithm has been developed and validated for a light-duty turbocharged common-rail diesel engine mounted in a test cell. Nevertheless, the developed methodology is general and can be applied to different turbochargers, both for spark ignited and diesel applications.

An Electromagnetic Energy Harvester for Rotational Applications

2017 ◽  
Author(s):  
Ben Gunn ◽  
Stephanos Theodossiades ◽  
Steve Rothberg ◽  
Tim Saunders
Keyword(s):  
Energy Harvester ◽  
Harmonic Component ◽  
Industrial Applications ◽  
Mean Value ◽  
Operating Conditions ◽  
Vibration Energy Harvester ◽  
Operating Bandwidth ◽  
Rotating Shafts ◽  
Speed Fluctuations ◽  
Excessive Noise

Many industrial applications incorporate rotating shafts with fluctuating speeds around a desired mean value. This often harmonic component of the shaft speed is generally undesirable, since it can excite parts of the system and can lead to large oscillations (potentially durability issues), as well as to excessive noise generation. On the other hand, the addition of sensors on rotating shafts for system monitoring or control poses challenges due to the need to supply power to the sensor and extract data from the rotating application. In order to tackle the requirement of powering sensors for structure health monitoring or control applications, this work proposes a nonlinear vibration energy harvester design intended for use on rotating shafts with harmonic speed fluctuations. The essential nonlinearity of the harvester allows for increased operating bandwidth, potentially across the whole range of shaft’s operating conditions.

scholarly journals A Nonlinear Concept of Electromagnetic Energy Harvester for Rotational Applications

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
B. E. Gunn ◽  
S. Theodossiades ◽  
S. J. Rothberg
Keyword(s):  
Energy Harvester ◽  
Harmonic Component ◽  
Industrial Applications ◽  
Mean Value ◽  
Operating Conditions ◽  
Vibration Energy Harvester ◽  
Operating Bandwidth ◽  
Rotating Shafts ◽  
Speed Fluctuations ◽  
Excessive Noise

Many industrial applications incorporate rotating shafts with fluctuating speeds around a required mean value. This often harmonic component of the shaft speed is generally detrimental, since it can excite components of the system, leading to large oscillations (and potentially durability issues), as well as to excessive noise generation. On the other hand, the addition of sensors on rotating shafts for system monitoring or control poses challenges due to the need to constantly supply power to the sensor and extract data from the system. In order to tackle the requirement of powering sensors for structure health monitoring or control applications, this work proposes a nonlinear vibration energy harvester design intended for use on rotating shafts with harmonic speed fluctuations. The essential nonlinearity of the harvester allows for increased operating bandwidth, potentially across the whole range of the shaft's operating conditions.

Diesel Engine Crankshaft Rotational Speed Fluctuation Analysis

2003 ◽  
Author(s):  
Jouji Kimura ◽  
Takashi Yamashita
Keyword(s):  
Diesel Engine ◽  
Rotational Speed ◽  
Fuel Injection ◽  
Fluctuation Analysis ◽  
Moments Of Inertia ◽  
Speed Fluctuation ◽  
Water Pumps ◽  
Speed Fluctuations ◽  
Engine Crankshaft

Crankshafts drive many accessories such as fuel injection pumps, camshafts, oil- and water pumps, compressors, fans, alternators etc. by using either gears or belts. Since crankshaft rotational speed fluctuates and engine accessories have moments of inertia, belts slip on pulleys and gears hit other gears, which results in noise and wear. This paper describes the mechanism of the rotational speed fluctuations of crankshafts by separating rotational speed fluctuations into those for a rigid and those for a torsional crankshaft for a V-type six-, eight- and ten-cylinder diesel engine. After that, crankshaft rotational speed fluctuations at crankshaft locations are discussed.

Tire Vibration Modes and Effects on Vehicle Ride Quality

1993 ◽  
Vol 21 (1) ◽  
pp. 23-39 ◽  
Author(s):  
R. W. Scavuzzo ◽  
T. R. Richards ◽  
L. T. Charek
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Operating Conditions ◽  
Modal Testing ◽  
Ride Quality ◽  
Vibration Modes ◽  
Inflation Pressure ◽  
Passenger Cars ◽  
Element Modeling ◽  
Road Surfaces

Abstract Tire vibration modes are known to play a key role in vehicle ride, for applications ranging from passenger cars to earthmover equipment. Inputs to the tire such as discrete impacts (harshness), rough road surfaces, tire nonuniformities, and tread patterns can potentially excite tire vibration modes. Many parameters affect the frequency of tire vibration modes: tire size, tire construction, inflation pressure, and operating conditions such as speed, load, and temperature. This paper discusses the influence of these parameters on tire vibration modes and describes how these tire modes influence vehicle ride quality. Results from both finite element modeling and modal testing are discussed.

scholarly journals A Numerical Investigation into the PAT Hydrodynamic Response to Impeller Rotational Speed Variation

2021 ◽  
Vol 13 (14) ◽  
pp. 7998
Author(s):  
Maxime Binama ◽  
Kan Kan ◽  
Hui-Xiang Chen ◽  
Yuan Zheng ◽  
Daqing Zhou ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Distribution Systems ◽  
Water Distribution ◽  
Production Efficiency ◽  
Operating Conditions ◽  
Energy Regulation ◽  
Speed Increase ◽  
Energy Field ◽  
Long Run ◽  
Study Results

The utilization of pump as turbines (PATs) within water distribution systems for energy regulation and hydroelectricity generation purposes has increasingly attracted the energy field players’ attention. However, its power production efficiency still faces difficulties due to PAT’s lack of flow control ability in such dynamic systems. This has eventually led to the introduction of the so-called “variable operating strategy” or VOS, where the impeller rotational speed may be controlled to satisfy the system-required flow conditions. Taking from these grounds, this study numerically investigates PAT eventual flow structures formation mechanism, especially when subjected to varying impeller rotational speed. CFD-backed numerical simulations were conducted on PAT flow under four operating conditions (1.00 QBEP, 0.82 QBEP, 0.74 QBEP, and 0.55 QBEP), considering five impeller rotational speeds (110 rpm, 130 rpm, 150 rpm, 170 rpm, and 190 rpm). Study results have shown that both PAT’s flow and pressure fields deteriorate with the machine influx decrease, where the impeller rotational speed increase is found to alleviate PAT pressure pulsation levels under high-flow operating conditions, while it worsens them under part-load conditions. This study’s results add value to a thorough understanding of PAT flow dynamics, which, in a long run, contributes to the solution of the so-far existent technical issues.

scholarly journals Impact of Operating Time on Selected Tribological Properties of the Friction Material in the Brake Pads of Passenger Cars

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 884
Author(s):  
Andrzej Borawski
Keyword(s):  
Tribological Properties ◽  
Operating Time ◽  
Friction Material ◽  
Operating Conditions ◽  
Direct Impact ◽  
Passenger Cars ◽  
Wear Factor ◽  
Brake Pads ◽  
Road Users ◽  
The Coefficient Of Friction

Braking systems have a direct impact on the safety of road users. That is why it is crucial that the performance of brakes be dependable and faultless. Unfortunately, the operating conditions of brakes during their operating time are affected by many variables, which results in changes in their tribological properties. This article presents an attempt to develop a methodology for studying how the operating time affects the value of the coefficient of friction and the abrasive wear factor. The Taguchi method of process optimization was used to plan the experiment, which was based on tests using the ball-cratering method. The results clearly show that the degree of wear affects the properties of the friction material used in the production process of brakes.

Measurement of Unsteady Flow in Pump-Turbine for Hydropower Using PIV Method

2009 ◽  
Author(s):  
Nobuhiko Fukuda ◽  
Satoshi Someya ◽  
Koji Okamoto
Keyword(s):  
Rotational Speed ◽  
Velocity Measurement ◽  
Numerical Procedure ◽  
Hydraulic Turbine ◽  
Operating Conditions ◽  
High Time ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Runner Blade ◽  
Wide Range

It is thought that the pressure fluctuation can occur due to the interaction between flow through guide vanes and flow into runner blades, resulting in a vibration of turbine and a blade cracking, in a hydraulic turbine operated in a wide range for flexible power demand. High accurate velocity measurement with high time/spatial resolution can help to clarify the mechanism of the interaction and to provide good experimental data for the validation of numerical procedure. So the aim of present study is to estimate the unstable velocity field quantitatively in the area between guide vanes and runner blades, using high time-resolved particle image velocimetry (PIV). Two types of velocity measurements were carried out, i.e., phase-locked measurement and high time sequential velocity measurement, in a pump-turbine model with 20 guide vanes and 6 runner blades. The characteristic of the flow field varied corresponding to the operating conditions such as flow rate and rotational speed. Opening angles of guide vanes were kept uniform. A clockwise vortex was generated at inside of the runner blade under smaller rotational speed. A counterclockwise vortex was separated at the backside of the runner blade under higher rotational speed. At any operating conditions, the velocity between guide vanes and runner blades oscillated periodically at the blade passing frequency.

Rolling Bearing Parametric Excitation of a Jeffcott Rotor System

2020 ◽  
Author(s):  
Ghasem Ghannad Tehrani ◽  
Chiara Gastaldi ◽  
Teresa Maria Berruti
Keyword(s):  
Parametric Excitation ◽  
Rotational Speed ◽  
Input Parameter ◽  
Equations Of Motion ◽  
Harmonic Balance Method ◽  
Rolling Bearing ◽  
Mean Value ◽  
Hertzian Contact ◽  
Rolling Bearings ◽  
Jeffcott Rotor

Abstract Rolling bearings are still widely used in aeroengines. Whenever rotors are modeled, rolling bearing components are typically modeled using springs. In simpler models, this spring is considered to have a constant mean value. However, the rolling bearing stiffness changes with time due to the positions of the balls with respect to the load on the bearing, thus giving rise to an internal excitation known as Parametric Excitation. Due to this parametric excitation, the rotor-bearings system may become unstable for specific combinations of boundary conditions (e.g. rotational speed) and system characteristics (rotor flexibility etc.). Being able to identify these instability regions at a glance is an important tool for the designer, as it allows to discard since the early design stages those configurations which may lead to catastrophic failures. In this paper, a Jeffcott rotor supported and excited by such rolling bearings is used as a demonstrator. In the first step, the expression for the time–varying stiffness of the bearings is analytically derived by applying the Hertzian Contact Theory. Then, the equations of motion of the complete system are provided. In this study, the Harmonic Balance Method (HBM) is used to as an approximate procedure to draw a stability map, thus dividing the input parameter space, i.e. rotational speed and rotor physical characteristics, into stable and unstable regions.

Fractal Analysis for Vibrational Signals Created in a Ball-Screw Machine Operating in Short- and Long-Range Tribological Tests

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Min-Chi Chang ◽  
Jeng Luen Liou ◽  
Chin-Chung Wei ◽  
Jeng-Haur Horng ◽  
Yueh-Ling Chiu ◽  
...  
Keyword(s):  
Long Range ◽  
Fractal Analysis ◽  
Rotational Speed ◽  
Operating Conditions ◽  
Ball Screw ◽  
Frictional Torque ◽  
A Value ◽  
Vibrational Signals ◽  
Inner Surface ◽  
Range Test

In the present study, the vibrational and frictional torque signals acquired from the forward-backward movements of a commercial ball-screw system were considered via mono fractal analysis. The short-range tests were carried out in order to investigate the effects of operating conditions, a nut's inner surface roughness and the applied pretension (preload) on the fractal dimension (Ds) and topothesy (G). The long-range test was conducted to observe the variations of vibrational and frictional torque signals and thus the fractal parameters acquired from the ball-screw operations under the condition of no fresh grease supply during the testing process. The effects of the ball-screw rotational speed and pretension on the G parameter of vibrations were greater than the Ds parameter. In the backward movement, the highest G value always occurred at the highest rotational speed (3000 rpm in this study). The Ds parameter generated in the forward movement by the nut's inner surface before polishing produced a value greater than that by the nut with a polished surface. The G parameter related to vibrational amplitudes showed a value before polishing greater than that after polishing. The unusual vibrational signals are assumed to be related to ball passing behavior. Their experimental frequency was verified to be consistent with the frequency predicted by the ball pass theory. An increase in the rotational speed can bring a significant increase in the number of ball-pass signals. The G parameter and its skewness data, defined for the number distribution function of the G peaks, showed values that in general increased with the test time if the fresh grease was not supplied during the long-range test.

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