KR20130019340A - Experimental method for testing vertical reaction resonance period and movement performance of multi supporters located in the sea with gravity base offshore structure - Google Patents

Abstract

PURPOSE: A method using a marine engineering aquarium for inspecting a vertical reaction resonance period and the movement performance of an underwater multi-supporter of a gravity-based marine structure is provided to obtain a safe and durable marine structure as designing the marine structure after inspecting the of an external force on the marine structure and the movement performance of the underwater multi-supporter in advance based on diverse marine information. CONSTITUTION: A method using a marine engineering aquarium for inspecting a vertical reaction resonance period and the movement performance of an underwater multi-supporter of a gravity-based marine structure is as follows. A marine structure model with a shape corresponding to a marine structure and reduced at a predetermined rate with respect to a real marine structure is manufactured. An external force caused by waves, tide, and wind generated in a real sea area, where the gravity-based marine structure is installed, is calculated. Sensors are installed in the lower part of the supporter and portions of the supporter above and below the water surface to that the vertical load which is actuated on the lower part of the supporter and the pressure of waves which is actuated on the supporter from on a water surface and above the water surface are measured. The marine structure model is seated in the marine engineering aquarium, and the external force is generated after installing a wind generator and a tide generator so that data measured by each sensor is obtained. [Reference numerals] (100) Wind power generator; (110) Gravity-fixed structure(fixed by own weight); (AA) Grasping tendency of slip and overturn due to an external force; (BB) Wind; (CC) Waves; (DD) Tide; (EE) Sand

Description

EXPERIMENTAL METHOD FOR TESTING VERTICAL REACTION RESONANCE PERIOD AND MOVEMENT PERFORMANCE OF MULTI SUPPORTERS LOCATED IN THE SEA WITH GRAVITY BASE OFFSHORE STRUCTURE}

The present invention implements the external force of the marine structure, especially the offshore structure for offshore wind power generation through an engineering tank, and then in the lower part of the support when the external force (waves, tides, wind) is generated against the support of the bottom of the surface of the marine structure In the marine engineering tank test method for the vertical load reaction resonant cycle and motion performance of multiple supports under the surface of gravity fixed marine structures that can quantitatively test the possibility of rolling and overturning by the load resonant reaction cycle and the load and external force. It is about.

Wind power is the most successful source of renewable energy. However, it is not easy to find a land for wind power generators in a country with a narrow country like Korea. Because of this, there is a growing interest in offshore wind power, with pillars in the sea and spinning windmills. In particular, the sea is abundant in the wind compared to the land has the advantage that it is advantageous for power generation.

Therefore, offshore wind power generation that converts kinetic energy of wind into mechanical energy using windmills and obtains electricity by turning generators is emerging as a clean energy source in the future.

In this regard, wind power plants are expanding rapidly in Europe, mainly in Germany. In Germany, 16,6543 wind turbines produce 16,628 kW (as of the end of December 2004). More than one wind farm was formed, producing electricity from as small as 3.6 kW to 100 kW in approximately one complex.

However, in case of Germany, due to the limitations of onshore wind power generation, recently, large-scale power generation facilities are being constructed through offshore wind farms, and this atmosphere is expanding throughout Western Europe.

The offshore wind power plant has a jack up system (Jack Up System) is used to easily install and handle the heavy objects because it is installed at sea.

Jack-up system is composed of jack-up part and locking part. Jack-up part is a means to lift a structure (offshore plant) having a weight of tens or hundreds of tons with rack and pinion, reducer and driving motor. The locking part is a means for positioning the lifting weight at a specific point.

The jack up method using this jack up system has the advantages of easy transport from the land to the installation site and easy construction. The effect is great. In addition, the upper and lower structures assembled on the land are shipped in a barge and transported to the site, and the legs are lowered and installed at the site. Will have

However, since the sea conditions vary from region to region, the term “jack-up platform structure” (hereinafter referred to as “sea structure”) is defined as the broadest concept that includes both offshore power plants and offshore plants. When designing, the area to be installed, that is, the coastal marine environment, that is, the wave, tide, wind, etc. must be thoroughly analyzed before design.

Therefore, based on this information, it is very important to test and predict their impact on the offshore structures to be installed in the future.

Nevertheless, in the field, methods for experimentally evaluating the safety, durability, and the like of marine structures based on information on the marine environment generated offshore in Korea are not suggested.

The present invention was created in view of the limitations of the prior art as described above, the external force generated in the sea based on the marine environment information of the domestic coast in advance, such as waves, tides, wind, etc. The vertical load reaction resonant resonant cycle of multiple supports under the surface of gravity-type fixed offshore structures to maximize the durability and safety by evaluating the impact on the structure and the resulting performance of the offshore structures in advance and reflecting the results. Its main purpose is to provide a marine engineering tank experimental method for athletic performance.

The present invention is a means for achieving the above object, a marine model structure manufacturing step of producing a marine model structure to have a shape corresponding to the gravity-type fixed offshore structure and reduced in a certain proportion to the actual size and weight, weight distribution; An external force calculation step of calculating an external force due to waves, tides, and winds generated in an actual sea area in which the gravity-fixed offshore structure is to be installed; A sensor installation step of installing a sensor on a support in an upper and lower position centering on the bottom and the surface of the support so that the vertical load on the support bottom of the marine model structure and the pressure of the wave on the support on the water surface and the water surface can be measured; The model installed on the marine model is installed in the marine engineering tank, and the wind force generator and the tidal current generator are installed to generate the external force calculated in the external force calculation step. After acquiring and expanding to the real sea by using the Froude analogy law, the marine model structure installation and measurement step of calculating the load resonance reaction period, the load value according to the frequency, and the wave pressure value that the offshore structure will receive in the real sea; It provides a marine engineering tank experimental method for the vertical load reaction resonant resonant period and the movement performance of the multiple support under the gravity fixed offshore structure, characterized in that it comprises a.

At this time, in the external force calculation step, the wave is an irregular wave to generate a target spectrum in order to generate a spectrum similar to the TMA spectrum suitable for the coast of Korea, after the wave, measuring the wave height using a wave height measuring instrument and performing the FFT analysis to verify Determined in a manner; The wind speed determines the maximum wind speed by applying Beaufort Scale on the basis of the determined wave height; The algae are also characterized by determining the maximum possible algal velocities in the sea area where the marine structures will be installed, based on statistics from the Meteorological Administration.

In addition, in the sensor installation step, the sensor for measuring the reaction force to the vertical load of the support is a calorimeter including a strain gauge, the sensor for measuring the pressure of the wave is characterized in that the wave pressure sensor.

In addition, between the bottom of the support and the calorimeter is placed a support box filled with sand so that the support can determine the possibility of falling or overturning due to waves or tides, the bottom of the support is provided to be seated on the sand It also has its features.

According to the present invention, based on a variety of marine information generated from the domestic coast, before the design of the offshore structure, the external force generated in the sea on the offshore structure and the design of the offshore structure after the test of its motion performance in advance to design a safer and more durable offshore The effect of enabling the construction of the structure can be obtained.

1 is an exemplary conceptual diagram of a marine structure in accordance with the present invention.
Figure 2 is a schematic diagram showing the installation of the marine model structure according to the present invention.
3 to 5 are graphs exemplarily showing an FFT analysis result for two-dimensional irregular waves using a calorimeter according to the present invention.
Figure 6 is an exemplary photograph showing an example being tested after the marine model structure is installed in the marine engineering tank according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Before describing the present invention, the following specific structural or functional descriptions are merely illustrative for the purpose of describing an embodiment according to the concept of the present invention, and embodiments according to the concept of the present invention may be embodied in various forms, And should not be construed as limited to the embodiments described herein.

In addition, since the embodiments according to the concept of the present invention can make various changes and have various forms, specific embodiments are illustrated in the drawings and described in detail herein. However, it should be understood that the embodiments according to the concept of the present invention are not intended to limit the present invention to specific modes of operation, but include all modifications, equivalents and alternatives falling within the spirit and scope of the present invention.

The marine structure described in the present invention is a gravity fixed marine model structure.

It is installed in an offshore engineering tank (a model tank that is scaled down to realize an environment similar to the actual marine environment), so that the actual offshore structure is scaled down to a certain size to perform the tests required under conditions similar to the actual marine environment. It is.

In addition, gravitational fixation is one of the basic facilities of offshore wind power generation, which is fixed and fixed by the weight of the offshore structure. In the southwest coast of Korea, the depth of the offshore is less than 60m. It is easy to transfer, easy to construct, and low cost.

More specifically, the marine engineering tank experimental method for the vertical load reaction resonant resonant cycle and the movement performance of the multiple support under the gravity-type fixed offshore structure according to the present invention is the gravity fixed offshore model structure manufacturing step, external force calculation step, sensor installation step, This includes the installation and measurement of marine model structures.

At this time, the sea model structure manufacturing step is a step that is produced in a reduced state to a certain ratio compared to the actual size of the sea structure using acrylic and synthetic resin.

In addition, the manufactured marine model structure is designed to be distributed according to the weight and weight distribution reduction ratio, it can be illustrated in the form as shown in FIG.

According to Figure 1, the marine model structure of the present invention is configured such that the three support is penetrated through the jack-up platform to which the wind turbine is fixed and fixed by the jack-up method by its own weight.

For ease of understanding, reference is made to FIG.

As shown in FIG. 2, three supporters 120 are installed in the jack-up platform 110 on which the wind power generators 100 are installed, respectively, so that the supporters 120 descend and are fixed to the bottom of the sea. Therefore, the jack-up platform 110 is supported, and the wind generator 100 installed thereon can perform wind power generation.

In the present invention, since the model structure for the experiment, the measurement equipment required for the experiment should be mounted.

To this end, as shown in Figure 2, the bottom of the support 120 to support and make a support box 130 filled with sand to create an environment corresponding to the actual sea floor, and the lower portion of the support box 130 A calorimeter 140 is installed to calculate the reaction force generated in the vertical direction.

In particular, sand is a method that can measure the force in the vertical direction of the marine structure overturning, overturning and the support 130 at a time that can occur in the actual marine environment, so that it can be configured to perform more accurate experiments do.

Of course, the above content is a part that must be described in the sensor installation step, but will be described in advance because it is closely related to the construction of the offshore structure.

In addition, it is difficult to precisely implement soil sedimentation due to Froude's similarity law (soil loss occurs during waves and tidal currents). In order to determine the possibility of rollover, it is desirable to set conditions that are more likely to fall and roll over than existing design conditions.

Thereafter, the external force calculation step is performed.

The external force calculation step is to create an environment similar to the actual marine environment, it is divided into wave determination process, wind speed determination process, tidal current determination process.

First of all, in the wave determination process, waves are irregular waves, and in particular, in order to generate a spectrum similar to TMA (Texel Storm, Marsen and Arsloe) spectrum suitable for the coast of Korea, the target spectrum is generated and waved, The wave is determined by measuring and verifying it by performing a Fast Fourier Transform (FFT) analysis.

For example, as shown in the experimental graph below, wave heights were measured for 102.4 and 2,048 seconds of 2D irregular waves fully developed in a marine engineering tank, and then FFT analysis was performed to acquire wave amplitude spectra for each frequency. After applying the weight to the spectrum and calculating the wave energy value for each frequency using the spectrum on which smoothing was performed, it was confirmed that application to a desired external force, particularly waves is possible.

At this time, the red part TMA spectrum in the graph is the value according to the empirical formula of wave energy spectrum suitable for the coast of Korea, and the green part TMA spectrum is the wave energy spectrum value measured in the marine engineering tank, and the wave energy in the empirical formula (red) as much as possible. It is preferable to use the irregular wave when approaching the proximity.

Next, the wind speed determination process determines the maximum wind speed by applying Beaufort Scale based on the determined wave height.

Under normal sea conditions, following the Beaufort wind class, where the height of the crest for each wind speed is determined, is the closest approach to the general sea conditions.

Here, the Beaufort Wind Scale is also referred to as the Beaufort Wind Scale as a measure of the wind speed. Invented by British Admiral F. Beaufort in 1805, this wind class classifies winds according to their degree of influence on voyages, with a tranquillity of zero and a typhoon of more than 120 kilometers per hour. In the meantime, it has been graded serially. Initially classified from sea conditions, it was later improved for use on land. The Beaufort wind tables currently in use were determined by the World Meteorological Organization (WMO) in 1962. The relationship between class B and wind speed V (m / sec) is based on empirical formula V = 0.836B3 / 2. It also shows contrast with land trees and building conditions on land, and is also widely used in nautical charts.

However, in the present invention, the wind pressure center point of the wind blade is located higher than the sea level due to the characteristics of offshore wind power generation, and because the influence of the wind speed acts as an important factor on the structure, by applying a weight higher than the wind speed shown in the Beaufort wind class chart It is desirable to decide.

In addition, the algae determination process is preferably to determine the maximum possible algal velocities of the sea area where the marine structures will be installed based on statistical data of the Korea Meteorological Administration.

When the external force is calculated in this manner, the sensor installation step is then performed.

The sensor installation step, the hydrometer (140, see Fig. 2) for measuring the vertical load described above, and the wave pressure sensor for measuring the pressure of the support (120, Fig. 2), that is the pressure of the wave at the surface of the water and above the surface of the water (150, see FIG. 2).

At this time, the calorimeter 140 uses a strain gauge, the reason for installing the calorimeter 140 is that the structure is perpendicular to the seabed ground when various external forces (waves, tides, wind) is generated in the marine model structure In order to measure the reaction force against the pressing force in the direction, and also the force in the vertical direction entering the calorimeter 140 is irregularly entered in time series (time) by various external forces, so interpreting such irregular data by frequency domain If (FFT) is performed, the load reaction resonance period and the load value for the period can be found.

For example, FIGS. 3 to 5 show the results of the FFT analysis on the two-dimensional irregular blue wave using the calorimeter 140 as an example. It is attached. This is only to show an example of using the sensor tensometer 140.

In addition, the wave pressure sensor 150 is for measuring the pressure of the wave when the period and the wave height of the wave is different, through which the relationship between the load received by the support 120 for the pressure of the wave.

Finally, the marine model structure installation and measurement step is performed.

In the marine model structure installation and measurement step, after attaching and installing the sensor for the support 120, the marine model structure is installed in the planned position of the marine engineering tank as shown in FIG. 6, and the algae generator and the wind generator are also planned. After installing at the position, apply the determined external force to acquire the measured data from each sensor, and then use Froude's similarity law to expand it to the actual sea, and load value according to the resonant reaction cycle and frequency that the sea structure will receive at the sea. And the pressure value of the wave are calculated.

The calculated values are reflected in the design of offshore structures.

By doing so, it is possible to check in advance what will happen when the offshore structure is actually installed, and it is expected that more safe and durable offshore structures can be designed and constructed.

In addition, to confirm the feasibility of the method of the present invention, assuming a 5 MW offshore wind power substructure jack-up platform, the behavior of the center of gravity of the offshore structure in the marine environment, the wave pressure applied to the platform support, and the components of the three support bases Experiments to verify the model were carried out in a marine engineering tank using the marine model structure according to the present invention.

, 풍속

2차원 불규칙파

,

, 2차원 규칙파

,

이며, 입사각은

,

이고, 수심은 조석간만의 차이를 고려한

였다.At this time, the external force and experimental conditions assuming real resolution

, Wind speed

2D irregular wave

,

, Two-dimensional regular wave

,

Where the incident angle is

,

Depth, considering the difference between tides

Respectively.

In addition, the maximum wave height that can be operated at 2.5m depth of marine engineering tank is 32cm (16m real sea wave height), but at 1.1m water depth for experiment, the maximum wave height is 26cm (Ground wave 13m) due to the ground effect due to low depth. ), 26cm was chosen as the maximum crest, and the cycle was selected based on the maximum crest.

Therefore, the period was selected from 1.2sec (real resolution period 7.071sec) to 1.8sec (real resolution period 12.728sec), and the selection background was a wave breaking phenomenon in which the broken part was broken when 1.0sec, which is a short period with respect to the maximum crest, was broken. (Wave Breaking) is generated and the reliability of the experimental data to be obtained is lowered, so the breaking wave does not occur based on 1.2sec. The long cycle, 2.0sec, was not able to realize the maximum crest 26cm due to the limitations of the marine engineering tank sowing machine, so 1.8sec was chosen as the maximum cycle.

According to the above conditions, the accuracy of the experiment was improved by deriving the calibration of tidal current, wind speed and wave height, and the accurate gain value of wave pressure sensor and component sensor.

The two-dimensional regular wave was determined to be within 3% of the error range using the transfer function obtained by the researcher.

In addition, we secured random wave data spectrums at home and abroad through a number of experiments on marine structures. In the case of two-dimensional irregular waves, we generated 100 component waves and generated random waves of the target spectrum. The wave closest to the spectrum (ITTC, JONSWAP, TMA Spectrum) was determined to reproduce the accuracy of the real-world wave.

The tidal current and the wind speed were used for the tidal current generator and the wind speed generator, and in order to realize the target flow velocity and wind speed, a flowmeter and anemometer were installed 2.5m in front, and the data of close to the exact flow rate were derived using trial and error method within 5%. The error range of was confirmed.

In this way, the accuracy of the experimental environment and conditions were increased to minimize the uncertainty of the result of the model experiment, and the same experiment was performed from the beginning to the end of the experiment to reduce the uncertainty of measurement for the experimenter.

Through these experiments, it was possible to confirm all the objects of the present invention, and therefore, it was expected to be able to design, manufacture, construct, and operate the domestic type marine structures suitable for the characteristics of the Korean coast, especially the southwest coast, more durable and safe.

In addition, the main specifications for marine engineering tanks are as follows.

-Major specifications of offshore engineering tank: 28m 22m 2.5m (L B D)

-Experimental tank depth: 0.8 ~ 2.5m

-Sowing machine: Implemented sowing module linked with water depth

Maximum crest: about 0.32 m

Wind speed of wind generator: 10m / sec

Current generator flow rate: max.0.6m / sec

100: wind power generator 110: jack up platform
120: support 130: support box
140: component meter 150: wave pressure sensor

Claims (4)

A marine model structure manufacturing step of manufacturing a marine model structure to have a shape corresponding to the gravity-type fixed marine structure and to be reduced in a certain proportion to the actual size, weight, and weight distribution;
An external force calculation step of calculating an external force due to waves, tides, and winds generated in an actual sea area in which the gravity-fixed offshore structure is to be installed;
A sensor installation step of installing a sensor on a support in an upper and lower position centering on the bottom and the surface of the support so that the vertical load on the support bottom of the marine model structure and the pressure of the wave on the support on the water surface and the water surface can be measured;
The model installed on the marine model is installed in the marine engineering tank, and the wind force generator and the tidal current generator are installed to generate the external force calculated in the external force calculation step. After acquiring and expanding to the real sea by using the Froude analogy law, the marine model structure installation and measurement step of calculating the load resonance reaction period, the load value according to the frequency, and the wave pressure value that the offshore structure will receive in the real sea; Marine engineering tank experimental method for the vertical load reaction resonant resonant period and the movement performance of the multiple support under the gravity fixed offshore structure, characterized in that it comprises a.
The method according to claim 1;
In the external force calculation step, the wave is an irregular wave to generate a spectrum similar to the TMA spectrum suitable for the coast of Korea, and after generating the wave, the wave height is measured using a wave measuring instrument, and the FFT analysis is performed. Determined;
The wind speed determines the maximum wind speed by applying Beaufort Scale on the basis of the determined wave height;
The tidal current is an offshore engineering tank for vertical load reaction resonant resonant cycle and motion performance of multiple supports under gravity-type fixed offshore structures, which is determined based on statistical data from the Korea Meteorological Administration. Experimental method.
The method according to claim 1;
In the sensor installation step, the sensor for measuring the reaction force to the vertical load of the support is a calorimeter including a strain gauge, the sensor for measuring the pressure of the wave is a gravity fixed offshore water surface structure, characterized in that the wave pressure sensor Experimental method of marine engineering tank for vertical load reaction resonance period and motion performance of multiple supports.
The method according to claim 3;
Between the bottom of the support and the calorimeter is placed a support box filled with sand so that the support can determine the possibility of falling or overturning due to waves or tide, characterized in that the bottom of the support is provided to be seated on the sand Experimental method of marine engineering tank for vertical load reaction resonant resonant cycle and movement performance of multiple supports under gravity fixed offshore structures.

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