RU2488835C2 - Method for contact measurement of wind speed and current profiles in perturbation zone - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method of measuring wind speed profile is realised using a system of anemometers vertically distributed on a rigid mast and connected to a multichannel recording device and a data storage, wherein the anemometers are arranged such that the lowermost of them lies lower than the minimum level of wave troughs and the uppermost lies higher than the maximum wave crest height. The same mast is fitted with an electronic water level gauge, which is switched with an additional electric signal switch such that the signal from each of the anemometers is recorded into the data storage only when the water level gauge indicates that said anemometer is in air, and its signal is not detected when in water. The method of measuring the current profile is realised using a system of current metres vertically distributed on a rigid mast and connected to a multichannel recording device and a data storage. The current metres are arranged such that the lowermost of them lies lower than the minimum level of wave troughs and the uppermost lies higher than the maximum wave crest height. The method of switching the current metres with the electronic water level gauge and the switch is such that signals from current metres are recorded in the data storage only when the current metres are located in water.

EFFECT: enabling measurement of wind speed and current profiles in a perturbation zone, high measurement accuracy and simple measurement process.

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Description

The present invention relates to methods for measuring hydrometeorological environmental parameters. In particular, the proposed method relates to measuring the vertical distribution (profile) of the air velocity (wind) and the flow of water (current) in the area of the excited air-water interface. Such measurements are mainly of scientific interest. The results obtained are used to solve practical problems (coastal construction, shipping safety, offshore oil and gas industry, etc.).

If the measuring instruments are in contact with the measuring medium, this measurement method is called contact. If the measuring devices are far from the measuring medium, and the information is obtained using video or radio observations, then the method is called remote (for example, remote measurement of the Earth's surface temperature). In this case, the method of contact measurement of air or water flow velocities is considered.

State of the art

At present, it is customary to use a special meter, an anemometer, to measure the vertical profile of the wind speed at a given geographical point on land or in water (lake, sea, etc.). [1, 2]. There is a wide variety of anemometers, differing in methods of measuring wind speed, inertia, accuracy and size. For our purposes, small-sized and low-inertia anemometers are acceptable, which are insensitive to moisture, for example, Wind Sonic type [3].

To measure the speed of water flows, propeller flow meters of various designs are used [1, 2], which are structurally known to be moisture resistant.

When performing wind profile measurements, anemometers are usually located on a rigid mast installed at a specified geographical point in the terrain. When measuring wind speed at one given height (the so-called horizon), it is enough to use only one anemometer. If necessary, measure the vertical wind profile using several anemometers 2, distributed vertically and located on a single mast 1 (Figure 1) [4]. (Several masts located next to each other can be used constructively, provided that they do not interfere with measurements). The measurement results recorded by anemometers, in a certain way (via electric wires) are transmitted to the information storage receiver 3 (Figure 1). Further, this information is subject to the processing required by the measurement objectives.

If you select a measurement point located in the water area (lake, sea, etc.), the lower boundary of the air flow is mobile due to the presence of wind waves at the air-water interface. Above the excited interface between media, measurements of the wind profile are complicated for a number of reasons, the main one being a moving water surface, because The movement of the media interface limits the vertical position of the meters. In this case, usually, the lowest meter is located at a sufficient distance from the highest possible position of the water surface, which is primarily due to the safety objectives of the meter, as well as the reliability of its readings [5].

A known method of contact measurement of the profile of wind speed, based on the use of vertically distributed on a rigid mast anemometers connected to a multi-channel recorder and storage of wind information [6].

One of the problems of measuring the wind profile over an excited surface of the water is the impossibility of applying known wind measurements in the region of small horizons, i.e. in the altitude zone, where water and air are alternately present. This zone will hereinafter be called the wave zone. In wave mechanics, it is generally accepted that the wave zone 4 vertically occupies the space between the deepest troughs and the highest wave crests (Figure 2).

The following is a solution to this problem, namely, a method of contact measurement of the wind profile in the wave zone. The same method is generalized to the case of measuring the current profile in the wave zone by replacing the anemometers with current meters and changing the switching of the meters.

SUMMARY OF THE INVENTION

To solve the problem, in contrast to the known method of contact measuring the profile of wind speed [6], the anemometers are positioned so that the lowest of them is below the minimum levels of the soles of the waves, and the highest is located at a height exceeding the maximum height of the wave crests (Fig .3). In this case, to implement the measurement of wind speed in the wave zone, an electronic water level meter 5 is installed on the same mast (Figure 3), which is switched with anemometers 2 using a standard multi-channel switch of the electric signal 6 so that the signal from each of the anemometers is recorded in information storage device 3 only when the water level meter indicates that the anemometer is in the air, and when the anemometer enters the water, its signal is not recorded.

In order to simplify the described process of measuring the wind profile in the wave zone, instead of a water level meter, small-sized capacitive sensors for the presence of water are used, rigidly attached directly under the housings of each of the anemometers, while maintaining the switching of the signals of the anemometers, water level sensors and a chopper, which ensures recording only in the information store, when for each anemometer its water sensor indicates that the anemometer is in the air.

In order to improve the accuracy of measuring wind speed, air humidity meters 7 are rigidly attached to the body of each anemometer (Figure 4), the signal from which is recorded through the switch into separate channels of the information storage device by analogy with the recording of signals from anemometers.

In order to measure the velocity profile of currents in the wave zone, the same set of meters is used (Figure 3) and the same method of recording information, only instead of anemometers 2, current meters are used, and the switching of the current meters with a water level meter and a breaker is set so that it provides recording of current measurements in the information storage device only when each of the current meters is in water.

In order to simplify the process of measuring the flow velocity profile in the wave zone, instead of a water level meter, small-sized capacitive water presence sensors are used that are rigidly mounted directly above the housings of each of the water flow meters, while maintaining the switching of the flow meters with water sensors and a chopper, providing recording of current measurements in the information storage device only when each of the flow meters is in water.

Possibility of implementation

An example of the implementation of the method for measuring the wind profile in the wave zone is illustrated in Figure 4, which shows: 1 - mast, 2 - anemometers, 3 - information storage device, 4 - wave zone, 5 - string water level meter, 6 - signal switch-switch, 7 - moisture meters.

All of the listed system elements are well-known devices that are widely used in various fields of measurement technology [1]. In particular, acoustic anemometers of the ATE-1034 type [7] can be used as low-inertia and small-sized anemometers that are insensitive to moisture, and a capacitive-type string meter can be used as a water level meter [1].

In order to increase the accuracy of measurements on all anemometers 2 falling into the wave zone, small-sized and low-inertia air moisture meters 7 (type НМР-233) are rigidly strengthened, the information from which is fed to individual channels of the storage device 3. This information allows taking into account the dependence of air density on its humidity , used to recalculate data obtained from anemometers 2 located in wave zone 4, which ensures the refinement of measurements of wind speed.

The proposed method for measuring the profile of wind speed is implemented as follows. Several anemometers 2 are located on a rigid mast rigidly fixed in vertical position 1, occupying vertically a wide range of heights, covering the wave zone 4, which is possible in this series of measurements. Each anemometer 2, located on some fixed horizon, measures the instantaneous wind speed at this horizon. To achieve the goal of taking measurements in the wave zone, on the same mast with anemometers (or very close to it), a water level meter 5 is located that measures the position of the water level along the vertical where the anemometers are located (Figure 4).

All wind speed meters and a water level meter in a certain way electrically commute with a multi-channel switch-switch 6, the operation of which is to turn on the anemometers only in those time periods when one or another of the anemometers 2, located at a fixed height, is above a constantly changing water level . Otherwise, i.e. when the anemometer enters the water, the switch turns off the anemometer, and its signal does not go to drive 3. Thus, only in the case when each specific anemometer 2, according to the readings of the water level meter 5, is in the air, the signal of this anemometer is controlled through the switch-switch 6, is fed to a multi-channel storage device 3.

As a result, information from each anemometer is collected on drive 3 into its own separate information channel only at those time periods when the water level meter 5 indicates that each given anemometer 2 is in the air. It turns out a multi-channel recording of a signal about the wind speed according to the number of horizons of the location of the anemometers (with a separate record for each anemometer). Then this information is subjected to standard processing (time averaging for each horizon). As a result, for each fixed horizon on which there is an anemometer, only when it is in the air a specific wind value is recorded. In total, this gives the vertical wind profile in the height range that is overlapped by the system of anemometers 2.

Since anemometers are usually calibrated for a specific air density, which substantially depends on its humidity, the accuracy of measurements of wind speed depends on air humidity. Since on a fixed horizon in the wave zone occupying a space where air and water are alternately present, air humidity can vary significantly, such variations in air humidity lead to a decrease in the accuracy of measurements of wind speed. Given this effect, the accuracy of measurements of wind speed in the wave zone can be improved by fixing small-sized humidity sensors 7 on the cases of anemometers 2 (Figure 4). At the same time, the switch-switch is switched with moisture meters 7 so that it passes their signals to the channels of the drive 3 only at that time when the anemometers and the moisture meters attached to them are above the water level. In this case, standard data processing for obtaining average wind is possible taking into account air humidity, which increases the accuracy of measurements.

In order to simplify the process of measuring the wind profile in the wave zone, instead of a water level meter 5, small-sized capacitive sensors for the presence of water are used, rigidly attached directly under the housings of each of the anemometers 2, while maintaining the switching of the anemometers, water sensors and a switch, which ensures the recording of the signal from each anemometer to the information storage device only when the water sensor indicates that the anemometer is in the air.

The described method is simply modified for the case of measuring the speed of currents. For the purpose of measuring the speed of currents in the wave zone, the anemometers 2 are replaced by current meters, leaving the rest of the instrument system unchanged (Fig 3). In this case, however, the switching of the water level meter 5 and the switch 6 with the current meters 2 is set so that the switch ensures that each of the current meters is turned on only when it is in the water. The method of accumulating information is performed by analogy with that for the case of measuring wind speed. In the case of measuring the profile of water flows, it is natural that humidity sensors are not needed.

In order to simplify the process of measuring the flow velocity profile in the wave zone, instead of a water level meter 5, small-sized capacitive water presence sensors are used that are rigidly mounted directly above the bodies of the water flow meters 2 (Figure 3), while maintaining the switching of flow meters, water sensors and a signal switch, providing a record of current measurements in the information storage device only when each of the current meters is in water.

Information sources

1. V.N.Kedrolivansky, M.S. Sternzat. Meteorological instruments. - L .; M: Hydrometeoizdat, 1953.

2. Kristensen, L., 1993: The cup anemometer and other exciting instruments. Tech. Rep. Risoe-R-615 (EN), Rise National Laboratory, 83 pp.

3.http: //www.gill.co.uk/products/anemometer/anemometer.htm

4. Bernstein, Abram B., 1967: A Note on the Use of Cup Anemometers in Wind Profile Experiments. J. Appl. Meteor., 6, 280-286.

5. A.Pena, S.-E. Gryning, Chamock's Roughness Length Model and Non-dimensionalWind Profiles Over the Sea. Boundary-Layer Meteorology (2008) 128: 191-203.

6. Patent of Russia No. 2030749.

7. http://www.aktakom.ru/kio/index.php?SECTION_ID=493&ELEMENT_ID=38092

Claims (3)

1. The method of contact measurement of the wind speed profile, based on the use of a system of anemometers vertically distributed on a rigid mast, connected by a signal switch to a multi-channel information storage device, characterized in that the anemometers are positioned so that the lowest of them is below the minimum levels of the soles of the waves, and the uppermost one is at a height exceeding the maximum height of the wave crests, and an electronic water level meter is installed on the same mast, which is connected to the anemometer with a signal and a switch so that the signal from each of the anemometers is recorded in the information storage device only when the water level meter indicates that this anemometer is in the air, and when it enters the water, its signal is not recorded. 2. The method of contact measurement of the wind velocity profile in the wave zone according to claim 1, characterized in that air humidity meters are mounted on the body of each anemometer and commutated with water level sensors and a signal switch, so that the signal of each moisture meter is recorded in the information storage device by analogy with the recording of the signal of the corresponding anemometer according to claim 1. 3. A method of contact measuring the profile of the current velocity, based on the use of a system of vertically distributed current meters on the rigid mast, connected by a signal switch to a multi-channel information storage device, characterized in that the current velocity meters are located so that the lowest of them is below the minimum levels soles of the waves, and the uppermost one is at a height exceeding the maximum height of the wave crests, and an electronic water level meter is installed on the same mast, They switch with the current meters and the signal switch so that the signal from each current meter is recorded in the information storage device only when the water level meter indicates that this current meter is in water, and if it enters the air, its signal is not recorded.

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