Digital Rotational Speed Measurement.

1995 ◽  
Author(s):  
Ronald J. Fischer
Keyword(s):  
Rotational Speed ◽  
Speed Measurement

Design of New Automobile Rotational Speed Measuring Device

2011 ◽  
Vol 383-390 ◽  
pp. 325-328
Author(s):  
Gui Yin Yu ◽  
Lu Zhang
Keyword(s):  
Rotational Speed ◽  
Phase Locked Loops ◽  
Frequency Division ◽  
Measurement Device ◽  
Measuring Device ◽  
Speed Measurement ◽  
Information Collecting

The automobile rotational speed measurement device, consisting of information collecting and processing, phase-locked loops, wave shaping, frequency division and display, can be applied for measurement of the rotational speed of automobiles with various cylinders.

A Research of High Precision Rotational Speed Measurement System Based on Infrared Sensor and Microcontroller

2013 ◽  
Vol 278-280 ◽  
pp. 680-683
Author(s):  
Zi Qin Ma ◽  
Ren Zhang ◽  
Da Li Kang ◽  
Wu Yang
Keyword(s):  
High Precision ◽  
Measurement System ◽  
Rotational Speed ◽  
Pulse Signal ◽  
Measuring Method ◽  
Infrared Light ◽  
Infrared Sensor ◽  
Flip Flop ◽  
Speed Measurement ◽  
Photoelectric Sensor

With the deep analysis on the rotational speed measurement and the error existed in the measurement process at present, this paper introduces a high precision rotational speed measurement system based on infrared sensor and microcontroller. This system combines with improved measuring method. The sensor is an infrared photoelectric sensor, and uses its characteristics of the autocollimator ensured accuracy of measurement. The photoelectric sensor outputs weak voltage pulse signal when it receives the reflected infrared light. And then the signal is processed by double-reversed amplification and twice pulse shaping circuit. The system uses the relevant logic functions of a D-type flip-flop to control two 16-bit microcontroller chip timing/counter turned on and off simultaneously, and calculates the rotation speed. At last, the result is displayed on LED by Microcontroller. This measurement system has high accuracy, fast sampling speed and wide measuring range.

Influence of Gas Feeding Position on the Performance of Radial-Inflow Hydrostatic Gas Ultra-Short Journal Bearings

2016 ◽  
Author(s):  
Chao Nie ◽  
Xiaojun Yan ◽  
Xia Chen
Keyword(s):  
Rotational Speed ◽  
Cfd Simulation ◽  
Journal Bearing ◽  
Maximum Speed ◽  
Test Rig ◽  
Thrust Bearings ◽  
Axial Stability ◽  
Speed Measurement ◽  
Gas Leaks ◽  
Better Than

To investigate the influence of gas feeding position on the performance of radial-inflow hydrostatic gas ultra-short (with a L/D value as 0.1) journal bearing two rotor-bearing system test rigs with two different feeding positions (central feeding and bottom feeding) for the journal bearing were designed. A rotor measurement system with an original rotational speed measurement program is built. Rotation experiments to measure the maximum rotational speed of rotors under different inlet pressure of journal bearing were conducted. It was found that, the rotor supported by the central feeding journal bearing worked better, and achieved a maximum rotational speed of 40000 rpm, (83.74m/s for the tip speed). While the test rig with bottom feeding journal bearing could not function well. To verify the reasons behind the failure mentioned above, the flow condition in the journal clearance and the rotor bottom clearance was analyzed by the CFD simulation. It shows that most of the journal bearing gas “leaks” into the rotor bottom clearance in the bottom feeding bearing test rig, disarranging the axial stability of the rotor and the normal functioning of the thrust bearings. In conclusion, the central feeding radial-inflow journal bearing is better than the bottom feeding one, for the better operability and higher maximum speed. And an ideal feeding position is supposed to make the journal bearing does not influence the axial stability of the rotor and the functioning of the thrust bearings.

scholarly journals Video-Tachometer Methodology for Wind Turbine Rotor Speed Measurement

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7314
Author(s):  
Francesco Natili ◽  
Francesco Castellani ◽  
Davide Astolfi ◽  
Matteo Becchetti
Keyword(s):  
Wind Turbine ◽  
Rotational Speed ◽  
Wind Farm ◽  
Turbine Rotor ◽  
Rotating Machinery ◽  
Speed Estimation ◽  
Rotor Speed ◽  
High Rotational Speed ◽  
Speed Measurement ◽  
Wind Turbine Rotor

The measurement of the rotational speed of rotating machinery is typically performed based on mechanical adherence; for example, in encoders. Nevertheless, it can be of interest in various types of applications to develop contactless vision-based methodologies to measure the speed of rotating machinery. In particular, contactless rotor speed measurement methods have several potential applications for wind turbine technology, in the context of non-intrusive condition monitoring approaches. The present study is devoted exactly to this problem: a ground level video-tachometer measurement technique and an image analysis algorithm for wind turbine rotor speed estimation are proposed. The methodology is based on the comparison between a reference frame and each frame of the video through the covariance matrix: a covariance time series is thus obtained, from which the rotational speed is estimated by passing to the frequency domain through the spectrogram. This procedure guarantees the robustness of the rotational speed estimation, despite the intrinsic non-stationarity of the system and the possible signal disturbances. The method is tested and discussed based on two experimental environments with different characteristics: the former is a small wind turbine model (with a 0.45 m rotor diameter) in the wind tunnel facility of the University of Perugia, whose critical aspect is the high rotational speed (up to the order of 1500 RPM). The latter test case is a wind turbine with a 44 m rotor diameter which is part of an industrial wind farm: in this case, the critical point regards the fact that measurements are acquired in uncontrolled conditions. It is shown that the method is robust enough to overcome the critical aspects of both test cases and to provide reliable rotational speed estimates.

Sign in / Sign up

Export Citation Format

Share Document