Research on Representative Engineering Applications of Anemometer Towers Location in Complex TopographyWind Resource Assessment

The typical location and number of anemometer towers in the assessed area are the key to the accuracy of wind resource assessment in complex topography.As calculation examples,this paper used two typical complex topography wind farms in Guangxi,Yunnan province in China.Firstly,we simulated the wind resource status of the anemometer tower in the Meteodyn WT software.Secondly,we compared the simulated wind resource with the actual measured data by the anemometer tower in the same situation.Thirdly,we analyzed the influence of anemometer tower location and quantity in the accuracy of wind resource assessment through the comparison results.The results showed that the range which the anemometer tower can represent is limited(<5 kilometers),and the prediction error more than 5%.Besides,the anemometer towers in special terrain areas(such as wind acceleration areas)cannot be used as a representative choice.The relative error of the simulated average annual wind speed by choose different number of anemometer towers is about 4%,and the grid-connected power generation more than 6%.The representative effect of anemometer towers is of crucial for improving the accuracy of wind resource assessment in engineering applications.

DATA PROCESSING ON LINEARIZATION OF HOT-WIRE ANEMOMETER

A method of data processing to determine the coefficients of linearization equations for 1050 anemometer (produced by Thermo-Systems Inc. -TSI, USA) with the sensors made of domestic hot wire using the program preferred in this Paper is described. By calculation and test, it is indicated that the error resulting from this method is about 0. 5% of the full scale and less than TSl's. By using this method we can set up the calibration curve according to the measurement range and the diameter of the hot wire at a certain accuracy.

Solar Driven Wind Speed Monitoring System Using Wireless or Wired Sensors

Instrumented towers are being constructed to characterize vertical wind profiles in order to improve the understanding and characterization of a desired environment up to 100 m. The site being measured is at a height of 2500 m over sea level, in one side of Sierra Madre Oriental, which crosses Mexico from North to South. As the site has no energy, it was powered by a photovoltaic system. Power consumption of two sets of sensors fixed at the tower was evaluated. The first sensor set consisted of a pulsed anemometer and a RH sensor having a 0 - 10 V output;these sensors used cables for transmitting the output signals. Three cup anemometers fixed at 25, 35 and 45 m high measured wind speed. Wireless sensors in the second set, requires of a power consumption and battery life study. Solar cells energized the sensors, becoming the installation and operation easier. The datalogger that acquired the RH and T measurements encountered an 11% voltage loss throughout the cable;cup anemometer measurements did not show variations due to its pulsed signals. Wireless sensors drew less energy from the PV system, resulting in battery overcharge. A dump regulator turned-on a 200 W lamp during the night when the battery voltage reached 14 V;the lamp was turned-off when the battery voltage felt beneath 11.5 V. Considering the high wind available, wireless sensors batteries were charged by small wind turbines combined with 5 W solar panels.

A new method of measuring optical turbulence of atmospheric surface layer at Antarctic Taishan Station with ultrasonic anemometer

To find the optimal location for large-aperture telescopes is a goal of astronomy. Chinese Antarctic astronomy has begun to flourish in recent years, and it is an urgent need in basic astronomical work to measure and analyze the optical turbulence spatiotemporal distribution in the Antarctic region. We analyzed turbulence data measured by a mobile atmospheric parameter measurement system from 30 December 2013 to 10 February 2014 at Antarctic Taishan Station. Because there is a discrepancy between the refractive index structure constant Cn2 measured by an ultrasonic anemometer with a single-point temperature structure function method and by micro-thermometer, a new method to measure C,2 with a temperature spectrum method is proposed herein. Through comparing long-term continuous Cn2 data derived from ultrasonic anemometer with those via the new method and micro-thermometer, trend, magnitude and measured weak turbulence of-2× 10-16m-2/3 are generally satisfactory. The reason for the discrepancy in Cn2 measurement between the ultrasonic anemometer with the old method and micro-thermometer is investigated.

A mobile polar atmospheric parameter measurement system:Ⅱ. First atmospheric turbulence observation at Antarctic Taishan Station

This is the second paper of a series devoted to atmospheric optical turbulence Cn^2 observation using a mobile polar atmospheric parameter measurement system. We present the initial results of Cn^2 measurement at Antarctic Taishan Station using micro-thermal sensors and a three-dimensional sonic anemometer at height -2.0 m above the snow surface. The site testing experiments were carried out during the 30th Chinese National Antarctic Research Expedition （CH1NARE）. We collected about 1 000 h of data between 30 December 2013 and 10 February 2014. The C,： curve exhibits clear daily structures, with two peaks around midnight and midday and two troughs around 7：30 and 17：00 local time （UTC＋5）. The mean C,2 is 2.7×10^-15 m^-2/3 and the 25th and 75th percentiles of the C,2 cumulative distribution are 9.6×10^-16 m^-2/3 and 6.2×10^-15 m^-2/3, respectively. Meteorological parameters such as temperature, relative humidity, wind speed, and air pressure are also presented.

Investigation of Stator Wake Variability in Single Stage Axial-Compressor

In this paper, we investigate the stator wake variability along the axial direction under different rotating speeds and mass flow conditions, in the terms of wake-core position, wake depth, wake width and wake velocity gradient. Experimental study is carried out in a single stage axial compressor by using Hot-wire Anemometer (HWA). Simultaneously, the numerical calculation is brought out in the same experiment rig. Firstly, we analyze the time-averaged velocity and radial vorticity at different axial positions, and explore the wake variability along the axial direction. Then, we present the effects of operation conditions on the wake-core position, and find out the inlet Mach number and incident angle are both the key influence factors of the wake-core position. Finally, we summarize four preliminary conclusions of the wake variability.

Wind Tunnel at LABINTHAP (Updated)

Flow behavior in the Thermal Engineering and Applied Hydraulics Laboratory (LABINTHAP) wind tunnel was investigated by measuring the velocity profiles, turbulence intensity and wall effects with a hot wire anemometer. Measurements were carried out under wind speeds 5, 15 and 30 m/s in planes located at 1.8, 2.6 and 3.4 m from flow inlet to the test section. The flow showed a good quality with a velocity variation less than 1%, turbulence intensity lower than 4% and the wall effects allow having an excellent work area in the test section for the velocities evaluated.

An Adaptive Response Compensation Technique for the Constant-Current Hot-Wire Anemometer

An adaptive response compensation technique has been proposed to compensate for the response lag of the constant-current hot-wire anemometer (CCA) by taking advantage of digital signal processing technology. First, we have developed a simple response compensation scheme based on a precise theoretical expression for the frequency response of the CCA (Kaifuku et al. 2010, 2011), and verified its effectiveness experimentally for hot-wires of 5 μm, 10 μm and 20 μm in diameter. Then, another novel technique based on a two-sensor probe technique—originally developed for the response compensation of fine-wire thermocouples (Tagawa and Ohta 1997;Tagawa et al. 1998)—has been proposed for estimating thermal time-constants of hot-wires to realize the in-situ response compensation of the CCA. To demonstrate the usefulness of the CCA, we have applied the response compensation schemes to multipoint velocity measure- ment of a turbulent wake flow formed behind a circular cylinder by using a CCA probe consisting of 16 hot-wires, which were driven simultaneously by a very simple constant-current circuit. As a result, the proposed response compensation techniques for the CCA work quite successfully and are capable of improving the response speed of the CCA to obtain reliable measurements comparable to those by the commercially-available constant-temperature hot-wire anemometer (CTA).

Effects of Orbital Motion on the Velocity Field of Boundary Layer Flow over a Rotating Disk

The purpose of this study is to investigate experimentally the effects of orbital motion on the velocity field of boundary layer flow over a rotating disk. The characteristics of velocity field at a fixed orbital angular section measured by a hot-wire anemometer show that the structure of the 3-dimensional boundary layer flow is deformed elliptically and displaced in a certain direction that is not in the orbital radial direction, but the direction of deformation depends on the combination of orbital and rotational directions. For coincide orbital and rotational directions, there are regions where the intensity of low-frequency disturbances increases rapidly in a certain central region (laminar region under pure rotation). The transient vortices, which form streaks on the coating film, are considered to be destroyed by low-frequency disturbances. However, for opposite orbital and rotational directions, the low-frequency disturbances are not observed in any section. As the adding orbital speed increases, the intensity of velocity fluctuations in the turbulence region becomes larger in the expected except in a certain region. This location of the region also depends on the direction of deformation or the combination of orbital and rotational directions.

Development of Verification Device for Starting Lever Pressing Automation of DEM6 Portable Three-cup Anemometer

At present,the verification system of wind speed in national 3MS provincial automatic weather station has been automated,but the wind speed verification of the DEM6 portable three-cup anemometer by the straight road wind tunnel cannot be automated.In order to record the reading of this verification,it is necessary to manually move the starting lever at the wind speed field during each verification.For this problem,a set of verification device for the DEM6 portable three-cup anemometer is developed based on automatic verification system of wind speed in the 3MS provincial automatic weather station.This device uses the the driving board of starting anemometer to connect with the pressing starting lever by a bar-shaped gap,so as to realize the remote control of the starting lever.It is convenient to use,and measure multiple sets of data at the same place.The measuring results are more accurate,thereby realizing automatic pressing of wind speed starting lever.

Anemometer Modified

A four cup commercial anemometer is modified as follows. Two cups with arms extending from the pivot are removed. The other two half spherical cups are re-placed by identical double cones, each of which is composed of two cones of different altitudes joined at the bases that are the same size. There is a stiff wire connecting the two double cones to the pivot at the midpoint so they are free to spin in the horizontal plane. They are parallel but oppositely oriented. When a fan is turned on aiming an air stream toward the double cones, they constantly rotate. Increasing the distance between the long axes of the two double cones causes the rotation rate to increase for the same setting of the fan. These results are qualitatively explained by reaction forces of a flowing fluid acting on the surfaces of solid bodies with front to back asymmetry in accord with Newton’s 3rd law (action equals reaction) published by the author earlier. Besides calibrating the modified anemometer for measuring wind speed, another practical application of the concept may be the generation of electricity by the natural winds.

Anemometer Modified II

A commercial anemometer was modified by replacing the four cups with four identical two-dimensional blades, each with a circular arc side and a flat side. The flat sides are fixed to four arms radiating from a pivot so that they are parallel to the wind direction. The rounded sides all point in the same direction around a circle. When the wind blows, there is a lift force on the rounded side of each blade and they unite in causing rotation about the pivot with the curved sides leading. The more blades the faster the rotation is a prediction.

Sensitivity-Enhanced Hot-Wire Anemometer by Using Cladding-Etched Fiber Bragg Grating

A sensitivity-enhanced hot-wire anemometer based on a cladding-etched optical fiber Bragg grating(FBG)coated with a layer of silver film and optically heated by using a 1480nm laser diode is demonstrated.The silver film absorbs the laser power to heat the FBG to a certain high temperature and the airflow cools down the FBG hot-wire with the cooling effect and hence the Bragg wavelength of the FBG is determined by the airflow velocity.Experimental measurement results show that the heating efficiency of the FBG hot wire is improved by 3.8times in magnitude by etching the fiber cladding from 125μm down to 73.4μm,and the achieved airflow velocity sensitivities,under a laser power of 200mW,are–3180pm/(m/s),–889pm/(m/s),–268pm/(m/s),and–8.7pm/(m/s)at different airflow velocities of 0.1m/s,0.5m/s,1.5m/s,and 17m/s,respectively.In comparison,the sensitivities are only–2193 pm/(m/s),–567 pm/(m/s),–161 pm/(m/s),and–4.9pm/(m/s)for the reference anemometer without cladding etching even at a much higher heating laser power of 530mW.These results prove that the method by using a cladding-etched FBG to improve sensitivity of FBG-based hot-wire anemometers works and the sensitivity is improved significantly.

Performance of a vehicle-mounted anemometer under cross wind: Simulation and experiment

Environmental wind measurements are essential for ensuring the operational safety of rail vehicles.In our previous work,al anemometer that can be mounted on the top of a train to achieve real-time measurements of wind speed and direction was proposed based on the pressure distributions around the cylindrical anemometer.However,the flow field on the top of the train is significantly influenced by the train;thus,the measured data might differ from the actual environmental wind parameters,particularly when trains are subjected to windbreak walls.In this study,simulations considering flow fields around trains installed with the proposed anemometer were conducted,and an improved delayed detached eddy simulation approach was adopted.Through simulations,the flow feld at the top of the train was analysed,and the aerodynamic characteristics of the anemometer were investigated.Accord-ingly,relationships between the measured wind characteristics and environmental wind characteristics are presented under various situations herein.Field experiments were performed for the proposed anemometer installed on a certain type of high-speed train along the Nanjiang Railway in China.The results obtained from both the numerical and experimental studies show that the proposed method has high accuracy for measuring environmental wind speed and direction when mounted on the top of a train.

SUBMERGED IMPINGING JETS WITHIN A FINITE WATER DEPTH

By use of the sheet of laser light and the tracing particle technology, flow visualization tests of complex flow structures for submerged impinging jets within finite water depths are conducted. Typical flow patterns of submerged impinging jets are analysed by the singular topology method. In order to reveal the mechanism of these flows, the diffusive characteristics and turbulent fluctuations of submerged impinging jets are measured by the hot-film anemometer.

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF TURBULENT AIR-CUSHION-CASCADE

Experimental and numerical studies of air-cushion-cascade were conducted and described. The SIMPLE algorithm combined with the normal k-Ε turbulence model was adopted to simulate the air-phase flow. The experiment was carried out by an IFA 300 anemometer. The flow field was measured for different ratios of main-stream velocity to jet velocity, different numbers of gaps and a couple of gap widths. The contour of the air-cushion was obtained, and the numerical calculations gave a closed-form result. The results show that the air-cushion thickness would increase with the increase of the jet velocity, gap width and gap number mainly determined by the jet in the former half cascade. The possibility to achieve anti-erosion by the turbulent jet was examined and confirmed.

A Multifunctional Airfow Sensor Enabled by Optical Micro/nanofber

Fiber-optic anemometers have attracted an increasing attention over the past decade owing to their high sensitivity,wide dynamic range,low power consumption,and immunity to electromagnetic interference.However,expensive instruments may limit their practical applications.Herein,a new type of airfow sensor based on optical micro/nanofber(MNF)is proposed and realized.The sensing element is a fexible polydimethylsiloxane(PDMS)cantilever embedded with a U-shaped MNF.Upon exposure to airfow,the induced defection of the cantilever results in a bending-dependent transmittance variation of the embedded MNF.The performance of the sensor can be engineered by tuning the cantilever thickness and/or the MNF diameter.When four cantilevers are arranged in two orthogonal directions,the transmittance of each cantilever will be dependent on both fow speed and direction.By analysing the output signals of the four cantilevers,omnidirectional airfow with fow speed within 15 m/s were experimentally measured.In addition,a variety of voice and respiratory signals can be monitored and distinguished in real-time using an optimized cantilever with a resolution of 0.012 m/s,presenting great potential for health monitoring applications.

Solids behavior in dilute zone of a CFB riser under turbulent conditions

The behavior of the solid phase in the upper zone of a circulating fluidized bed riser was studied using a phase Doppler anemometer. Glass particles of mean diameter 107μm and superficial gas velocities UE covering the turbulent and the beginning of the fast fluidization regime were investigated. Three static bed heights were tested. Ascending and descending particles were found co-existing under all oper ating conditions tested, and at all measurement locations. Superficial gas velocity proved/happened to have a larger effect on descending particles at the wall and on ascending particles in the central region. Transversal particle velocities in both directions （toward the center and toward the wall） behaved rela- tively equivalently, with only slight difference observed at the wall. However, observation of the number of particles moving in either transversal direction showed a change in bed structure when increasing Ug. Furthermore, a balance was constantly observed between the core zone and the annulus zone where the mutual mass transfer between these two zones occurred continuously. Transition from a slow to a fast particle motion was accompanied by a transition to high levels of velocity fluctuations, and was found corresponding to the appearance of significant solid particle flow rate.

AN EXPERIMENTAL STUDY OF FLOW FIELD IN THE FLUID HOMOGENIZER

A Laser Doppler Anemometer (LDA) is used to measure and study the flow field in the working chamber of a homogenizer. Flow Patterns, distributions of mean and fluctuating velocities, shear rates are obtained in details. The characteristics of the flow field and the basic principles of homogenizing are presented. These results are very helpful for the improvement of fluid homogenizers.

AN EXPERIMENTAL INVESTIGATION ON DIVIDING FLOW THROUGH A CHANNEL BY LDA

A Laser Doppler Anemometer (LDA) is used to measure and study the dividing flows in channels which are straight and annular with single opening or multi-openings. Flow patterns, distribution of velocities and pressures, and allotment of now volumes are obtained in detail. Results show that dividingflow is very complicated.Dimensitons of the openings, shape o f the channel, and the backpressure in the channel affect the flow patterns of the dividing flow.