Fiber anemometer

Summary The described fiber anemometer permits measuring small constant and variable discharges and velocities of liquid and gas, direction of currents, and the characteristics of turbulence. The lower limit of measurable velocities is fractions of mm · sec^–1. The special features of this anemometer are insensitivity to electrical and magnetic disturbances, and the possibility of taking measurements in chemically agressive media. It can be useful for measurements in hydrodynamics, meterology, oceanography, pneumatics, chemical technology, and low-speed aerodynamics.Translated from Izmeritel'naya Tekhnika, No. 6, pp. 42–44, June, 1968.     

Errors of digital methods of measuring the frequency of the single-frequency signal of a laser Doppler anemometer

An error analysis is made for the electronic processor a laser Doppler anemometer (LDA), using digital methods of measuring the frequency of the Doppler signal. We consider a method for evaluating the period of the high-frequency filling of the LDA signal from the coordinates of the zero of the process and a method for estimating the signal frequency from the position of the maximum value of the spectral density. The results reported show that the limiting values of the total error of measurement of the LDA signal frequency can be decreased to 0.1–0.3%.Translated from Izmeritel'naya Tekhnika, No. 10, pp. 43–46, October, 1993.     

A laser-type anemometer for measuring the velocities of air streams

A laser-type anemometer is described which measures the mean velocity and velocity fluctuations in turbulent streams.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 5, pp. 888–890, May, 1973.     

A virtual instrument for automatic anemometer calibration with ANN based supervision

A fully automatic anemometer calibrator intended for performing fast and accurate calibrations has been developed to fulfill the increasing demand and strict requirements of the wind energy industry. Different sensors are connected to a computer where a virtual environment acquires and processes the incoming signals and controls a wind tunnel, allowing the calibration of the anemometer at the pre-selected air speed values. An important part of the resulting complex virtual environment is a supervising system, based on artificial neural networks and able to check and handle the possible malfunctions and deviations within the calibration process.     

超声波风速仪的理论建模及分析

深入分析了超声波在空气中的传播特性,研究了基于传播时间和声强变化的超声波风速仪理论模型,从传播时间和声强两个方面描述了超声波风速仪的基本原理,并在不同风速和相对风向的条件下进行了实验,取得了和理论模型一致的结果,为研制超声波风速仪提供了理论基础。     

Pressure dependence of hot-wire anemometer readings

Translated from Izmeritel'naya Tekhnika, No. 5, pp. 21–23, May, 1991.     

Thermoelectric anemometer for measuring air flow speeds

Conclusions The thermoelectric anemometer was tested under mining conditions for measuring the speed of air along underground workings. The tests have shown that the instrument is more accurate than existing impeller or cup-type anemometers and is suitable for measuring low air speeds. It is also possible to measure air depressions by means of this instrument, thus providing depression surveys by means of one instrument instead of two, namely, a microammeter and an anemometer which are normally used in mines. The instrument has three ranges: 0.001–0.3; 0.1–6 and 1–20 m/sec; its error is 1.5% and its over-all dimensions are 90×110×130 mm, with a weight of 1.2 kg.     

Intelligent heating control of a new ice-free anemometer

The wind industry has grown over the years along with the collective desire to produce clean energy. High wind potential sites are often located in northern regions where harsh climatic conditions arise. The performance of anemometers, which provide essential measurements to wind turbine operation and wind resource assessment, is then jeopardized by ice build-up and snow accumulation. These conditions result in the need for heated instruments able to remain ice-free regardless of weather conditions while minimizing energy consumption. The main objective of this work was to develop an intelligent heating control for a new generation of ice-free anemometers. The controller is based on vision recognition of ice build-up on the cups of the anemometer using a neural network. Heating power is applied according to the icing state and the icing history of the instrument. Primary results have shown that, for a completely ice-free performance, the developed controller uses an average of less than two thirds of the energy consumed by common control systems similar to those used by other ice-free anemometers available on the market.     

Hot-wire anemometer with temperature compensation using only onesensor

In conventional constant temperature hot-wire anemometers, the compensation for the fluid temperature is done by using two sensors. In this paper, the analysis of an anemometer circuit using only one sensor, operating alternately at two different temperatures is presented. The effect of the amplifier input offset voltage is taken into account, and its influence on the measurement of fluid velocity is quantified. Preliminary experimental results are also presented     

A digital hygrometer

A digital hygrometer using a polyimide capacitive humidity sensor is developed. The capacitance change of the sensor due to adsorption of water vapor in the atmosphere is detected by a switched-capacitor digital capacitance bridge controlled by a one-chip microcomputer and is displayed as relative humidity with 0.1% resolution. The accuracy of the hygrometer calibrated by a two-point method is solely determined by the temperature dependence and the long-term drift of the dielectric sensitivity of the sensor and is estimated to be 2%     

Response of phase Doppler anemometer systems to nonspherical droplets

The Phase Doppler Anemometer (PDA) technique measures particle diameter assuming sphericity. A means for detecting nonsphericity has usually been implemented in commercial PDA systems to avoid sizing errors if the sphericity assumption is not valid. In the present research the response of standard and planar PDA systems is examined experimentally in more detail by passing nonspherical droplets of known shape through the measurement volume. The effectiveness of nonsphericity detection schemes can be evaluated, and furthermore the influence of the droplet oscillations on the frequency and phase evolution of individual signals can be quantified. The light scattering from such particles has been simulated by using geometric optics, and the computed response of standard and planar PDA systems agrees well with the experimental observations. We conclude with some remarks concerning the possibilities of characterizing the nonsphericity with PDA systems.     

A microprocessor-based digital flickermeter

A flickermeter is an instrument able to simulate and measure the human optical sensation caused by illumination variations due to small-amplitude, low-frequency changes of mains power supply voltage. A flickermeter that has been designed, constructed, and found to meet the internationally agreed performance specifications set out by the IEC (International Electrotechnical Commission) is described. The system, already in commercial service, has been implemented around a microprocessor and presents a full range of I/O interfaces for possible applications in a variety of operational environments. Several unique and demanding design obstacles are related, along with experiences in achieving their solutions. Particular attention is directed to the matter of a nonlinear-phase filter design, task that required a novel Darwinian evolutionary approach which exploits non-equispaced frequency sampling in order to simultaneously satisfy both harsh step response and frequency response accuracy constraints     

A digital coincidence method

A digital coincidence method is described in which the amplitude is digitized and the time of each pulse from the ionizing radiation detectors is recorded. The features of the processing of the digital amplitude-time measurement data are described in detail. It is shown that the digital coincidence method has a time resolution defined solely by the resolving power of the detectors.Translated from Izmeritelnaya Tekhnika, No. 12, pp. 53–58, December, 2004.This revised version was published online in April 2005 with a corrected cover date.