Random process-based stochastic analysis of multirotor hovering noise under rotational speed fluctuations

2021 ◽  
Vol 33 (12) ◽  
pp. 127107
Author(s):  
Jaeheon Jeong ◽  
Jeongwoo Ko ◽  
Huisang Cho ◽  
Soogab Lee
Keyword(s):  
Random Process ◽  
Rotational Speed ◽  
Stochastic Analysis ◽  
Speed Fluctuations

scholarly journals A novel vibration-based fault diagnostic algorithm for gearboxes under speed fluctuations without rotational speed measurement

2017 ◽  
Vol 94 ◽  
pp. 14-32 ◽  
Author(s):  
Liu Hong ◽  
Yongzhi Qu ◽  
Jaspreet Singh Dhupia ◽  
Shuangwen Sheng ◽  
Yuegang Tan ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Diagnostic Algorithm ◽  
Speed Measurement ◽  
Fault Diagnostic ◽  
Speed Fluctuations

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.

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.

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.

"Stochastic analysis of the concentration variability in a dimensional heterogeneous aquifer

1990 ◽  
Vol 26 (10) ◽  
pp. 2591-2602 ◽  
Author(s):  
Efstratios Vomvoris
Keyword(s):  
Stochastic Analysis ◽  
Heterogeneous Aquifer

Scheme of multiplicative linearization of a random process

2020 ◽  
Vol 0 (97) ◽  
pp. 103-109
Author(s):  
Zoya Nagolkina
Keyword(s):  
Random Process
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