JP2007085795A - Wave characteristic measuring method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine ship speed from a measured value by a pressure gage installed on the bow, and to determine a wave characteristic by analyzing pressure fluctuation. <P>SOLUTION: A. A plurality of characteristic curves relative to pressure measured values by a plurality of pressure gages and inflow angles in each draft and each inflow angle are determined by a water tank test using a model ship or theoretical calculation. B. Ship speed through the water is determined based on the pressure measured values of an actual ship wherein the plurality of pressure gages are arranged on a position approximately on the hull center line on the hull outer plate surface under the bow water surface of the actual ship and on a position approximately at equal interval from the hull center line of the port and the starboard, a water density, and the plurality of characteristic curves. C. Relative water level fluctuation is determined based on the measured values by the pressure gages. D. A vertical displacement amount is determined based on outputs from upper and lower accelerometers arranged on the actual ship, and absolute water level fluctuation is determined based on the vertical displacement amount and the relative water level fluctuation. E. An encountered wave spectrum is determined based on the absolute water level fluctuation. F. A wave spectrum is determined based on the encountered wave spectrum, the ship speed through the water, and a wave encounter angle determined separately. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for measuring wave characteristics and a device therefor, and in particular, arithmetic processing for obtaining wave characteristics by obtaining a ship speed based on a measured value of a pressure gauge installed at the bow of a hull and analyzing pressure fluctuations. About.

Conventionally, as a device for measuring wave characteristics such as wave height, for example, “a device 3 that calculates the vertical displacement of the bow based on a signal from the vertical acceleration sensor 1 of the bow, a signal from the device 3, and a signal from the wave height meter 2” Receiving device 4 for calculating the absolute wave height, device 5 for calculating the power spectrum by accumulating signals from the device 4 for a certain period of time, and calculating the wave encounter angle by setting the wave direction from the ship's direction The device 6 for converting the power spectrum based on the encounter frequency obtained from the power spectrum calculation device 5 into the wave frequency base using the encounter wave angle calculated by the device 6, and the device 7 A device 8 for identifying a significant wave height and an average wave frequency in response to an output signal from the signal, and a final calculation device for calculating an average wave length, a wavelength and a frequency of a spectrum peak based on the signal from the device 8 Constructed equipped and. "It has been proposed (see Patent Document 1).
Japanese Patent Laid-Open No. 06-273198 (Summary, FIG. 1)

  In the above prior art (Patent Document 1), the wave spectrum of the absolute wave height is obtained from the vertical fluctuation at the wave height meter position obtained from the wave height meter and the vertical accelerometer, and by giving the value of the wave direction and the ship speed to this The wave spectrum is calculated, but there is a problem that the ship speed must be calculated and input by some other method.

  The present invention has been made in order to solve such a problem, and obtains a ship speed based on a measurement value obtained by a pressure gauge installed at the bow of a hull and analyzes a pressure fluctuation to thereby obtain a wave characteristic. It is an object of the present invention to provide a wave characteristic measuring method and apparatus capable of obtaining the above.

  In the wave characteristic measuring method according to the present invention, a plurality of pressure gauges are provided at a position on the hull center line below the bow water surface on a substantially hull center line, and at positions that are substantially equidistant from the hull center line on the port and starboard. A step of obtaining a plurality of characteristic curves related to pressure measurement values of the plurality of pressure gauges and the inflow angle for each draft and for each inflow angle by a tank test or theoretical calculation using the arranged model ship; The pressure measurement value of a pressure gauge of an actual ship in which a plurality of pressure gauges are arranged at a position on the hull center line of the hull outer plate surface at a position substantially equidistant from the hull center line on the port side and starboard side. , A step of obtaining a water speed based on the density of water and the plurality of characteristic curves, a step of obtaining a relative water level fluctuation based on a measurement value of the pressure gauge, and a vertical acceleration disposed on the actual ship Calculate the vertical displacement based on the output of the meter, A step of obtaining an absolute water level fluctuation based on the vertical displacement and the relative water level fluctuation; a step of obtaining an encounter wave spectrum based on the absolute water level fluctuation; the encounter wave spectrum; And a step of obtaining a wave spectrum based on a separately obtained wave meeting angle.

  In the wave characteristic measuring method according to the present invention, a plurality of pressure gauges are provided at a position on the hull center line below the bow water surface on a substantially hull center line, and at positions that are substantially equidistant from the hull center line on the port and starboard. A step of obtaining a plurality of characteristic curves related to pressure measurement values of the plurality of pressure gauges and the inflow angle for each draft and for each inflow angle by a tank test or theoretical calculation using the arranged model ship; The pressure measurement value of a pressure gauge of an actual ship in which a plurality of pressure gauges are arranged at a position on the hull center line of the hull outer plate surface at a position substantially equidistant from the hull center line on the port side and starboard side. Determining the ship speed based on the density of water and the plurality of characteristic curves; determining the encounter pressure spectrum based on the measured value of the pressure gauge; and determining the ship speed and the water separately. Pressure frequency as a function of measured wave angle Obtaining an encounter wave spectrum based on a response function and the encounter pressure spectrum, obtaining a wave spectrum based on the encounter wave spectrum, the speed of the water vessel, and the wave encounter angle; It is equipped with.

  In the wave characteristic measuring method according to the present invention, a plurality of pressure gauges are provided at a position on the hull center line below the bow water surface on a substantially hull center line, and at positions that are substantially equidistant from the hull center line on the port and starboard. A step of obtaining a plurality of characteristic curves related to pressure measurement values of the plurality of pressure gauges and the inflow angle for each draft and for each inflow angle by a tank test or theoretical calculation using the arranged model ship; The pressure measurement value of a pressure gauge of an actual ship in which a plurality of pressure gauges are arranged at a position on the hull center line of the hull outer plate surface at a position substantially equidistant from the hull center line on the port side and starboard side. Determining the speed of the watercraft based on the density of the water and the plurality of characteristic curves, the measured value of the pressure gauge disposed substantially on the center line of the hull, and the port side and starboard side of the actual ship. Measured values of multiple pressure gauges arranged respectively A step of determining the pressure cross spectrum based, pressure frequency response function as a function of the ship's speed relative to the water, in which a step of obtaining the direction wave spectrum on the basis of said pressure cross spectrum.

  The wave characteristic measuring apparatus according to the present invention includes a plurality of hull outer plate surfaces below the bow surface at positions substantially on the hull center line and positions at substantially equal intervals from the hull center line on the port and starboard. The pressure gauge, the vertical accelerometer placed almost on the hull centerline on the surface of the hull skin below the bow, and the tank test or theoretical calculation using a model ship, A plurality of characteristic curves relating to the pressure measurement value of the pressure gauge and the inflow angle are obtained, and the speed of the water vessel is determined based on the pressure measurement value of the pressure gauges, the density of water, and the plurality of characteristic curves. Processing to determine, processing for determining relative water level fluctuation based on the measured value of the pressure gauge, vertical displacement based on the output of the vertical accelerometer arranged on the actual ship, the vertical displacement and the relative water level fluctuation The absolute water level fluctuation is calculated based on A wave spectrum is obtained based on the process of obtaining the encounter wave spectrum based on the absolute water level fluctuation, the encounter wave spectrum, the speed of the water vessel, and the separately obtained wave encounter angle. And a control unit that performs processing.

  The wave characteristic measuring apparatus according to the present invention includes a plurality of hull outer plate surfaces below the bow surface at positions substantially on the hull center line and positions at substantially equal intervals from the hull center line on the port and starboard. A plurality of characteristic curves relating to pressure measurement values and the inflow angles of the plurality of pressure gauges are obtained for each draft and for each inflow angle by a water tank test or theoretical calculation using a pressure gauge and a model ship, and the plurality of pressures A process for obtaining a water speed based on the pressure measurement value of the gauge, a density of water, and the plurality of characteristic curves, a process for obtaining an encounter pressure spectrum based on the measurement value of the pressure gauge, A process of obtaining an encounter wave spectrum based on a pressure frequency response function having a function of a water vessel speed and a separately obtained wave encounter angle and the encounter pressure spectrum, the encounter wave spectrum, and the anti-water vessel Based on the speed and the wave meeting angle There are those comprising a control unit that performs a process for obtaining the wave spectrum.

  The wave characteristic measuring apparatus according to the present invention is arranged at a position on the hull center line below the bow surface substantially on the hull center line, and at a position substantially equidistant from the hull center line on the port side and starboard side. A plurality of pressure gauges, a second plurality of pressure gauges arranged on the port side and the starboard side of the ship, and a tank test or a theoretical calculation using a model ship, for each draft and inflow angle, A plurality of characteristic curves relating to the pressure measurement value of the pressure gauge and the inflow angle are obtained, and the speed of the water vessel is determined based on the pressure measurement value of the pressure gauges, the density of water, and the plurality of characteristic curves. A pressure cross based on a desired treatment, a measured value of a pressure gauge arranged substantially at a position on the center line of the hull among the first plurality of pressure gauges, and a measured value of the second plurality of pressure gauges Processing for obtaining a spectrum and pressure as a function of the speed of the watercraft A frequency response function, in which a control unit that performs a process of determining the direction wave spectrum on the basis of said pressure cross spectrum.

  As described above, in the present invention, it is possible to obtain the ship's speed based on the measured value by the pressure gauge installed at the bow of the hull, and to obtain the wave spectrum by analyzing the pressure fluctuation, There is no need to obtain a separate speed, and the equipment can be simplified.

  The inventors have developed a measurement method for obtaining a water flow velocity (= water vessel speed) / flow direction flowing into the hull by installing a plurality of pressure gauges at the bow and analyzing their pressure measurement values. Since the ship navigates in the waves in the actual sea area, the measured pressure also fluctuates with time due to the waves and the hull motion caused by the waves. The ship speed is obtained from the average value of these fluctuation amounts, but it is possible to analyze the waves that cause the pressure fluctuation amount on the contrary. When wave analysis becomes possible, the incident wave can be determined simultaneously with the average (vs. water) ship speed.

  By the way, the wave period of waves found here is the wave period of encounters affected by ship speed. For example, in the case of a direction wave, the wave period of encounter is shortened due to the influence of the ship speed. This is called the encounter wave cycle. In addition, the irregular fluctuation distribution of waves corresponding to this encounter wave period is called an encounter wave spectrum. What we really want is the spectrum of waves that the ship encounters (enters the ship) (the wave spectrum without the effect of ship speed), which is the encounter wave period, wave encounter angle, It can be determined if the ship speed is known. According to the present invention, since the encounter wave cycle and the speed of the ship against water can be obtained, it is possible to specify the waves (wave spectrum) encountered by the ship using these.

  In the following description, an example in which the ship speed is obtained based on the measurement value of the pressure gauge that is the basis of the present invention is referred to as Embodiment 1, and an example in which the wave spectrum is obtained by using the ship speed is described as an embodiment. It demonstrates as 2-4.

Embodiment 1. FIG.
The present invention has been made based on the fact that the ship speed can be obtained based on the measured value by the pressure gauge installed at the bow of the hull. Focusing on the measurement of ship speed, it will be described as Embodiment 1.

FIG. 1 is a block diagram showing the configuration of a ship speed measuring apparatus which is the basis of the present invention. This ship speed measuring device is composed of pressure sensors 1 ₁ to 1 ₃ , a control unit 2, a storage unit 3, a display unit 4 and an operation unit 5. Although the vertical accelerometer 6 is illustrated in FIG. 1, this is used in the second embodiment described later, and is ignored in the first embodiment.

The pressure sensor 1 ₁ to 1 ₃ supplies, for example, external implantable or stainless is made from those electronic such as a piezoelectric element, each pressure measurement P _c, the P _p and P _s to the control unit 2 . Capacity of the pressure sensor ₁ 1 to 1 _3, for example, when the boat speed is 10 m / s (about 20 knots or equivalent), since the stagnation pressure is about 5.1Maq = about 50 kPa, stagnation in equivalent about 100 kPa (1 atm It is sufficient if the boat speed is about 27 knots in terms of pressure. As shown in FIG. 2, the pressure sensor 1 ₁ is bow underwater hull center line disposed hull surface near the position (see a broken line in FIG. 2), the pressure sensor 1 ₂ and 1 ₃ are bow under water respectively Are arranged on the hull outer plate surface which is almost equidistant from the hull center line of the port and starboard.

  The control unit 2 includes a CPU (Central Processing Unit), a digital signal processor (DSP), a sequencer, and the like. Based on a characteristic curve creation program, a ship speed measurement program, and the like stored in the storage unit 3, the characteristic curve creation is performed. The entire ship speed measuring device is controlled by executing processing, ship speed measuring process, and the like. That is, for example, when the characteristic curve creation program is read out, it is read into the control unit 2 and controls the operation of the control unit 2. When the characteristic curve creating program is started, the control unit 2 executes a characteristic curve creating process described later under the control of the characteristic curve creating program.

  The storage unit 3 includes a semiconductor memory such as a RAM, a ROM, or a flash memory, an FD drive to which an FD (floppy (registered trademark) disk) is mounted, an HD drive to which an HD (hard disk) is mounted, and an MO (optical MO disk drive to which a magnetic disk is mounted, or CD (compact disk) -ROM, CD-R (Recordable), CD-RW (ReWritable), DVD-ROM, DVD-R, DVD-RW, etc. CD / DVD drive. The storage unit 3 stores in advance a characteristic curve creation program to be executed by the control unit 2, a ship speed measurement program, and other various programs, and the control unit 2 performs the above-described characteristic curve creation program and ship speed measurement program. Used for work when executing various other programs. The display unit 4 includes a CRT display, a liquid crystal display (LCD), an electroluminescence (EL) display, a plasma display panel (PDP), or the like. The operation unit 5 includes a keyboard including a numeric keypad, an enter key, or a function key, a pointing device such as a mouse, a touch pad, or a pen device.

Next, the operation of the above ship speed measuring device will be described. First, by conducting a water tank test in which the ship speed measurement device of this example is mounted on a model ship, a characteristic curve used when the ship speed measurement device of this example is mounted on an actual ship is created. Here, mounting the ship speed measuring device on the model ship means mounting the pressure sensor in the ship speed measuring device, and other devices are not necessarily mounted. Hereinafter, the creation of the above characteristic curve will be described with reference to the flowchart shown in FIG. When the ship speed measuring device of this example is set to the characteristic curve creation mode, the control unit 2 sets the draft change number n (n is a natural number), which is the number of times to change the draft, and sets the draft change number n. Set 1 to a variable k for counting. Further, the speed V against water input by the inspector operating the operation unit 5 is stored in a predetermined storage area of the storage unit 3 (step SP1). Here, to change the draft, the pressure measurement P _c which is output from the pressure sensor 1 ₁ to 1 _3, since P _p and P _s is affected by draft changes in the vessels, the characteristic curve of each draft This is because it needs to be created. Moreover, the reason for setting the anti-watercraft speed U is that it is necessary when the control unit 2 creates a characteristic curve described later.

Then, the water tank, the bow underwater hull pressure sensor as shown in FIG. 2 to the surface 1 ₁ to 1 ₃ model ship arranged in the optimum position with the oblique Wataru angle at a constant rate Towing. The skew angle corresponds to the inflow angle β, and the speed corresponds to the watercraft speed U set in step SP1. Thus, pressure measurement values P _c from the pressure sensor 1 ₁ to 1 _3, since P _p and P _s is supplied, the control section 2 stores in a predetermined storage area of the storage unit 3, the display unit 4 Display (step SP2). Since the characteristic curve to be created is a function of the inflow angle β, as will be described later, the model ship is changed at a constant speed by changing the skew angle, for example, every 5 degrees from -30 degrees to +30 degrees. Towing. Accordingly, the control unit 2, each oblique Wataru angle, i.e., a predetermined storage area of the pressure measurement values P _c, P _p and P _s to the storage unit 3 from the pressure sensor 1 ₁ to 1 ₃ of each inflow angle β And displayed on the display unit 4.

The pressure measurement P _c of each inflow angle β from the pressure sensor 1 ₁ to 1 _3, the P _p and P _s is supplied all, the control unit 2, the inflow angle β from a predetermined storage area of the storage unit 3 The pressure measurement values P _c , P _p and P _s for each and the speed V of the watercraft are read out, and the values (P _p −P _s ) / (P _c −P _s ) and values (P _c− P _s ) / ρU ² is calculated and then stored in a predetermined storage area of the storage unit 3 and displayed on the display unit 4 (step SP3). ρ is the density of water filled in the aquarium. The value (P _p −P _s ) / (P _c −P _s ) is a parameter for calculating the actual inflow angle β of the actual ship on which the ship speed measuring device of this example is mounted. For example, the value P _p > P _s for the flow from the starboard and (P _p −P _s )> 0, whereas P _p <P _s for the flow from the starboard (P _p− P _s ) <0. Further, the value (P _c −P _s ) / ρU ² is a parameter for calculating the actual water speed U of the actual ship on which the ship speed measuring device of this example is mounted. Note that the value (P _p −P _s ) / (P _c −P _s ) and the value (P _c −P _s ) / ρU ² are both dimensionless. In the case of similar shapes having different sizes but the same shape, the same value can be used.

Next, the control unit 2 creates a first characteristic curve of the inflow angle β and the value (P _p −P _s ) / (P _c −P _s ), and then stores it in a predetermined storage area of the storage unit 3. At the same time, it is displayed on the display unit 4 (step SP4). That is, the control unit 2 reads the inflow angle β and the corresponding value (P _p −P _s ) / (P _c −P _s ) from a predetermined storage area of the storage unit 3, and the inflow angle is plotted on the horizontal axis of the graph. A first characteristic curve indicated by a curve a in FIG. 4 is created by placing β and placing the value (P _p −P _s ) / (P _c −P _s ) on the vertical axis and connecting the points. Next, the control unit 2 creates a second characteristic curve of the inflow angle β and the value (P _c −P _s ) / ρU ^2, and then stores the second characteristic curve in a predetermined storage area of the storage unit 3 and the display unit 4. (Step SP5). That is, the control unit 2 reads the inflow angle β and the corresponding value (P _c −P _s ) / ρU ² from a predetermined storage area of the storage unit 3, A value (P _c −P _s ) / ρU ² is placed on and connected to create a second characteristic curve indicated by a curve b in FIG.

  Next, after incrementing the variable k by 1 (step SP6), the control unit 2 determines whether the variable k is greater than the draft change number n. If the determination result is “NO”, the control unit 2 returns to Step SP2 and repeats the processing of Steps SP2 to SP6 described above. And if the variable k becomes larger than the draft change number n, the judgment result of step SP7 will be "YES", and the control part 2 will complete | finish a series of processes. By repeating the processing of steps SP2 to SP5 described above n times, a first characteristic curve and a second characteristic curve for each draft are created, and each is stored in a predetermined storage area of the storage unit 3, It is displayed on the display unit 4. Note that the first characteristic curve and the second characteristic curve can be expressed by mathematical formulas by applying them to polynomials.

  Here, the basis for creating the first characteristic curve and the second characteristic curve will be described. When an object with a blunt shape, such as a sphere, is placed in a flow of water or the like, the pressure is greatest at a point directly in front of the flow of water or the like, and the pressure drops rapidly as the point moves away from the point. It is known to go. The relationship between the flow of water and the pressure applied to the object can be expressed theoretically in the case of an object with a structurally simple shape such as a sphere, but it can be represented by a general shape such as the shape of a bow. This object cannot theoretically be expressed by mathematical formulas. Therefore, it is necessary to investigate what characteristic curve tendency the relationship between the flow of water or the like and the pressure applied to the object shows by using an experiment or a numerical analysis method. The first characteristic curve and the second characteristic curve tend to change greatly and monotonously even with a slight change in the inflow angle β (for example, change almost linearly with respect to the change in the inflow angle β and have a large gradient). ) Is desirable.

  The quality of the characteristic curve tends to affect the accuracy of the inflow angle β and water speed U measured on the actual ship. It is necessary to keep. As for the optimal arrangement of the pressure sensor, as described above, it is desirable that the tendency of the first characteristic curve and the second characteristic curve changes substantially linearly with respect to the change of the inflow angle β, and the gradient thereof is large. For example, it is desirable to search for such a position by a prior calculation using the Hess & Smith method, and a position where the position is satisfied is an optimum arrangement position. Since the optimal placement position of the pressure sensor differs depending on the shape of the ship, as a general numerical value, the depth of the left and right placement positions cannot be limited to how many meters away from the hull center line. . In addition, even if the distance is long, the characteristic curves tend not to be good if they are arranged in parallel, so each pressure sensor should be arranged so that the normals of the arrangement positions of the pressure sensors intersect at as large an angle as possible. It is better to place it. Here, the Hess-Smith method (Hess & Smith) is a flow distribution that is one of the hydrodynamic singularities in fluid mechanics when an object is present in a flow. This is a method for analyzing the flow by obtaining the strength by numerical analysis.

Next, the measurement of the water speed U and the inflow angle β when the ship speed measuring device of this example is mounted on an actual ship will be described with reference to the flowchart shown in FIG. As the bow underwater hull surface of the pressure sensor 1 ₁ to 1 ₃ as shown in FIG. 2 cruising make at sea like the actual ship arranged in the optimum position. Thus, pressure measurement values P _c from the pressure sensor 1 ₁ to 1 _3, since P _p and P _s is supplied, the control section 2 stores in a predetermined storage area of the storage unit 3, the display unit 4 indicate. Further, the control unit 2 is supplied with the seawater density ρ measured by a density meter (not shown) and stores it in a predetermined storage area of the storage unit 3 and displays it on the display unit 4 installed in the bridge, for example ( Step SP11). The seawater density ρ may be a value converted from the measured water temperature or salt water concentration, or may be input by operating the operation unit 5 by the inspector.

Next, the control unit 2 reads the pressure measurement values P _c , P _p and P _s from the predetermined storage area of the storage unit 3 and calculates the value (P _p −P _s ) / (P _c −P _s ). Thereafter, it is stored in a predetermined storage area of the storage unit 3 (step SP12). Next, the control unit 2 reads the value (P _p −P _s ) / (P _c −P _s ) and the first characteristic curve from the predetermined storage area of the storage unit 3, and as shown in FIG. After obtaining the inflow angle β in the first characteristic curve when taking the value (P _p −P _s ) / (P _c −P _s ), the inflow angle β is stored in a predetermined storage area of the storage unit 3 and displayed on the display unit 4. Display (step SP13).

Next, the control unit 2 reads the value β and the second characteristic curve from a predetermined storage area of the storage unit 3, and as shown in FIG. 4, the value (P _c− P _s ) / ρU ² (this value is assumed to be A) and then stored in a predetermined storage area of the storage unit 3 (step SP14). Since the value (P _c −P _s ) / ρU ² is equal to the value A, (Equation 1) holds. Next, the control unit 2 reads out the pressure measurement values P _c and P _s and the seawater density ρ from the predetermined storage area of the storage unit 3 and substitutes (Equation 1) into the modified (Equation 2). After calculating the ship speed U against water, a series of processing is terminated (step SP15).
(P _c −P _s ) / ρU ² = A (Equation 1)
U = {ρA / (P _c −P _s )} ^1/2 (Expression 2)

Thus, in this embodiment, substantially the hull center line disposed hull surface, port and starboard hull bow underwater Each pressure sensor 1 ₂ and 1 ₃ under bow water pressure sensor 1 ₁ When placed on the surface of the hull skin that is approximately equidistant from the center line, the first characteristic curve and the second characteristic curve are obtained in advance by a tank test using a model, and when mounted on an actual ship, the pressure sensor 1 ₁ a pressure measurement value P _c, P _p and P _s from to 1 _3, a sea water density ρ from density meter, based on the first characteristic curve and the second characteristic curve, when the ship is sailing The ship's speed U and the inflow angle β are calculated. Since the first characteristic curve and the second characteristic curve can be created with high accuracy by a tank test using a model ship, the water speed U and the inflow angle β of the actual ship based on this can be calculated with high accuracy. it can.

  In the above description, an example in which the first characteristic curve and the second characteristic curve are obtained by a water tank test using a model is shown, but the present invention is not limited to this. For example, the first characteristic curve and the second characteristic curve may be obtained by theoretical calculation using a numerical analysis method. Examples of the numerical analysis method include the above-mentioned Hess & Smith method based on the potential flow theory and a computational fluid dynamics (CFD) simulation for numerically solving a flow equation of motion. Further, the forms of the first characteristic curve and the second characteristic curve need not be limited to those described above, and it is sufficient that β and U can be obtained with high accuracy.

  From the above explanation, it became clear that the measurement of the speed of the watercraft was possible by using the measured value of the pressure sensor (pressure gauge). Next, based on the measured value of the pressure sensor (pressure gauge) Embodiments of a wave characteristic measuring apparatus for obtaining a wave spectrum or the like (wave characteristics) will be described as Embodiments 2 to 4.

Embodiment 2. FIG.
FIG. 6 is a flowchart showing a process of calculation processing of the wave characteristic measuring apparatus according to the second embodiment of the present invention, and FIG. 7 is an explanatory diagram thereof. The configuration of the wave characteristic measuring apparatus is basically the same as that shown in FIG. 1. In the second embodiment, the wave speed measuring apparatus shown in FIG. Used as a measuring device. And the control part 2 performs each calculation mentioned later (this is the same also in Embodiment 3 and 4 mentioned later).

Here, the measurement pressure by site measured ship's speed relative to the water (the position of the pressure sensor 1 ₁₎ P and p (t). Here, (t) represents a time variation value. Assuming that the pressure value is almost equal to the head, the relative water level fluctuation Z _r (t) is obtained by the following (Equation 3).

Further, the vertical displacement Z _p (t) at the position P is obtained by integrating the vertical acceleration measured by the vertical accelerometer 6 twice and by the following (formula 4).

Further, if the height of the part P from the water surface is h ₀ , the relationship between the relative water level fluctuation Z _r (t) and the absolute water level fluctuation ζ (t) has the following relationship (Equation 5). From the water level fluctuation Z _r (t), the height h ₀ and the vertical displacement Z _p (t), the absolute water level fluctuation ζ (t) can be obtained as shown in (Expression 6). h ₀ can be obtained from the difference between the draft and the mounting height of the part P from the ship bottom.

The absolute water level fluctuation ζ (t) obtained here is converted into an encounter wave spectrum S (ω _e ) by power spectrum calculation. Various methods such as Blackman-Tukey method, FFT method, and MEM method have been proposed and used for power spectrum calculation. For example, as shown in the following (Equation 7),

Thus, the autocorrelation function C (τ) is obtained, and the encounter wave spectrum can be obtained by performing the Fourier transform.

  Further, it is converted into a wave spectrum S (ω) by the following calculation.

The relationship between the encounter wave frequency ωe and the wave frequency ω is given as follows.

  Here, U is the ship speed, and is measured by the water speed measurement shown in the first embodiment. Λ is the wavelength, and χ is the encounter angle between the ship and the wave. This wave meeting angle χ is an angle when entering from an oblique direction with χ = 0 ° when entering from the front of the bow. For example, the transverse wave is χ = 90 ° and the following wave is χ = 180 °. The wave meeting angle χ is determined by visual observation on the ship, for example, the wave direction is obtained by image processing of the radar image on the ship, and the wave direction is estimated by wave estimation from the atmospheric pressure arrangement / wind speed / wind direction distribution. It shall be obtained separately by such methods.

From the obtained wave spectrum, the significant wave height H and the average wave period T of the encounter wave are obtained by (Equation 13).

Embodiment 3. FIG.
FIG. 8 is a flowchart showing a process of calculation processing of the wave characteristic measuring apparatus according to the third embodiment of the present invention. The configuration of the wave characteristic measuring apparatus is the same as that shown in FIG. As in the case of the second embodiment, the pressure fluctuation p (t) is obtained from the measured pressure at the site P, and the power spectrum calculation is performed on the pressure p (t) to include the influence of the hull fluctuation. A pressure spectrum S _p (ω _e ) is obtained. From this pressure spectrum S _p (ω _e ), the spectrum of the encounter wave can be obtained by the following equation.

Here, H _p (ω _e ; U, χ) is a frequency response function of pressure at the pressure gauge position, and can be obtained by theoretical calculation or model test using the ship speed U and the wave meeting angle χ as parameters. Practically, it is preferable to prepare a pressure frequency response function as a database by using several ship speeds and wave meeting angle waves as parameters in advance, and interpolate with the actual ship speed and wave direction. The actual ship speed is obtained from the water speed obtained from this apparatus, and the wave meeting angle is obtained by some method as in the second embodiment. The method for obtaining the wave spectrum from the obtained encounter wave spectrum and obtaining the wave parameters such as the significant wave height and the average wave period of the encounter wave is the same as in the second embodiment. In the third embodiment, it is not necessary to install a vertical accelerometer for removing the hull shaking effect.

Embodiment 4 FIG.
FIG. 9 is a flowchart showing a process of calculation processing of the wave characteristic measuring apparatus according to the fourth embodiment of the present invention, and FIG. 10 is an explanatory diagram thereof. In the fourth embodiment, each of the pressure gauges for water velocimeters (installed at the bow) and the pressure gauges installed at a distance sufficiently away from the pressure gauges (for example, installed at the left and right side of the ship near the center of the hull) ) Is used to obtain the wave spectrum. Now, P ₁ a pressure gauge, ..., as installed in M positions of the P _M, p _m (t) the pressure fluctuations measured by the respective pressure gauge, m = 1, ..., a M. From these pressure fluctuation measurement values, the cross spectrum S _mn (ω _e ), m, n = 1 _,. The following relationship exists between the cross spectrum S _mn (ω _e ) and the directional wave spectrum E (ω, χ).

Here, H _pm (ω, χ) is a pressure frequency response function in the pressure gauge m, and the ship speed V and the wave encounter angle χ can be obtained as parameters as in the third embodiment. H ^* _pm (ω, χ) is a conjugate complex number of _Hpm (ω, χ). Using the relationship of (Equation 16) above, the directional wave spectrum E (ω _e , χ) of the encounter can be obtained from the cross spectrum S _mn (ω _e ). Various methods such as a conventional parameter method, an extended maximum entropy method, an extended maximum likelihood method, a Bayes method, and a nonlinear programming method have been proposed for this analysis. The above (Formula 16) is an example. Further, the directional wave spectrum E (ω, χ) can be obtained from the directional wave spectrum E (ω _e , χ) of the encounter using (Equation 9). Since the obtained directional wave spectrum E (ω, χ) includes a wave direction component, the main direction of the wave encounter angle can be obtained. Further, from this directional wave spectrum, the significant wave height H and the average wave period T of the encounter wave can be obtained using (Equation 13). However, in this case,

である。この演算方法では、船体動揺影響を除去するための上下加速度計６の設置が不要になる。また、波出会角χも自動的に求めることができる。

It is. In this calculation method, it is not necessary to install the vertical accelerometer 6 for removing the influence of the hull shaking. In addition, the wave meeting angle χ can be automatically obtained.

  In the case of the fourth embodiment, it is necessary to additionally install a pressure gauge in the vicinity of the center of the hull in addition to the bow pressure gauge for the water velocimeter, but the additional pressure gauge position, the bow pressure gauge position, The distance may be specified from the resolution accuracy of the wavelength of the encounter wave. Moreover, when installing in the hull center vicinity, it is also possible to use the data measured with the existing pressure gauge used as a draft meter in the hull center part.

It is a block diagram which shows the structure of the ship speed measuring apparatus which is Embodiment 1 of this invention. It is a conceptual diagram which shows an example of arrangement | positioning of a pressure sensor. It is a flowchart for demonstrating the characteristic curve creation process of a control part. It is a figure which shows an example of a characteristic curve. It is a flowchart for demonstrating the ship speed measurement process of a control part. It is the flowchart which showed the process of the arithmetic processing of the wave characteristic measuring apparatus which concerns on Embodiment 2 of this invention. It is explanatory drawing of Embodiment 2 of this invention. It is the flowchart which showed the process of the arithmetic processing of the wave characteristic measuring apparatus which concerns on Embodiment 3 of this invention. It is the flowchart which showed the process of the arithmetic processing of the wave characteristic measuring apparatus which concerns on Embodiment 4 of this invention. It is explanatory drawing of Embodiment 4 of this invention.

Explanation of symbols

1 ₁ to 1 ₃ Pressure sensor, 2 control unit, 3 storage unit, 4 display unit, 5 operation unit, 6 vertical accelerometer.

Claims (6)

Aquarium test using a model ship in which multiple pressure gauges are arranged at a position on the hull center line on the hull outer plate surface below the bow water surface and at a position that is substantially equidistant from the hull center line on the port side and starboard side Alternatively, by theoretical calculation, for each draft and each inflow angle, obtaining a plurality of characteristic curves related to the pressure measurement values of the plurality of pressure gauges and the inflow angle;
Pressure of the pressure gauge of an actual ship in which a plurality of pressure gauges are arranged at a position on the hull center line on the hull outer plate surface below the bow water surface and a position that is substantially equidistant from the hull center line on the port side and starboard side. Calculating the speed of the watercraft based on the measured value, the density of water, and the plurality of characteristic curves;
Obtaining a relative water level fluctuation based on the measured value of the pressure gauge;
Obtaining a vertical displacement amount based on an output of a vertical accelerometer disposed on the actual ship, and obtaining an absolute water level variation based on the vertical displacement amount and the relative water level variation;
Obtaining an encounter wave spectrum based on the absolute water level fluctuation;
A wave characteristic measurement method comprising: a step of obtaining a wave spectrum based on the encounter wave spectrum, the speed with respect to the water vessel, and a separately obtained wave encounter angle. Aquarium test using a model ship in which multiple pressure gauges are arranged at a position on the hull center line on the hull outer plate surface below the bow water surface and at a position that is substantially equidistant from the hull center line on the port side and starboard side Alternatively, by theoretical calculation, for each draft and each inflow angle, obtaining a plurality of characteristic curves related to the pressure measurement values of the plurality of pressure gauges and the inflow angle;
Pressure of the pressure gauge of an actual ship in which a plurality of pressure gauges are arranged at a position on the hull center line on the hull outer plate surface below the bow water surface and a position that is substantially equidistant from the hull center line on the port side and starboard side. Calculating the speed of the watercraft based on the measured value, the density of water, and the plurality of characteristic curves;
Obtaining an encounter pressure spectrum based on the measurement value of the pressure gauge;
Obtaining an encounter wave spectrum based on the pressure frequency response function and the encounter pressure spectrum as a function of the vessel speed and the separately obtained wave encounter angle;
A wave characteristic measurement method comprising: a step of obtaining a wave spectrum based on the encounter wave spectrum, the speed with respect to water, and the wave encounter angle. Aquarium test using a model ship in which multiple pressure gauges are arranged at a position on the hull center line on the hull outer plate surface below the bow water surface and at a position that is substantially equidistant from the hull center line on the port side and starboard side Alternatively, by theoretical calculation, for each draft and each inflow angle, obtaining a plurality of characteristic curves related to the pressure measurement values of the plurality of pressure gauges and the inflow angle;
Pressure of the pressure gauge of an actual ship in which a plurality of pressure gauges are arranged at a position on the hull center line on the hull outer plate surface below the bow water surface and a position that is substantially equidistant from the hull center line on the port side and starboard side. Calculating the speed of the watercraft based on the measured value, the density of water, and the plurality of characteristic curves;
A step of obtaining a pressure cross spectrum based on a measurement value of a pressure gauge disposed substantially at a position on the center line of the hull and a plurality of pressure gauges disposed on the port side and starboard side of the actual ship; and
A wave characteristic measuring method, comprising: a step of obtaining a directional wave spectrum based on a pressure frequency response function that is a function of the ship speed against water and the pressure cross spectrum. A plurality of pressure gauges arranged at a position on the hull center line of the hull skin plate surface below the bow water surface and at a position that is substantially equidistant from the hull center line on the port and starboard;
A vertical accelerometer arranged at a position on the hull centerline on the hull skin surface below the bow water surface;
By a water tank test or a theoretical calculation using a model ship, a plurality of characteristic curves related to the pressure measurement values and the inflow angles of the plurality of pressure gauges are obtained for each draft and each inflow angle, and the pressure measurements of the plurality of pressure gauges are obtained. Disposed on the actual ship, a treatment for obtaining the water speed based on the value, the density of water, and the plurality of characteristic curves, a process for obtaining the relative water level fluctuation based on the measurement value of the pressure gauge, and A process for obtaining a vertical displacement amount based on the output of the vertical accelerometer, a process for obtaining an absolute water level fluctuation based on the vertical displacement quantity and the relative water level fluctuation, and a process for obtaining an encounter wave spectrum based on the absolute water level fluctuation. A wave characteristic measuring device comprising: a control unit that performs a process for obtaining a wave spectrum based on the encounter wave spectrum, the speed with respect to water, and a separately obtained wave encounter angle . A plurality of pressure gauges arranged at a position on the hull center line of the hull skin plate surface below the bow water surface and at a position that is substantially equidistant from the hull center line on the port and starboard;
By a water tank test or a theoretical calculation using a model ship, a plurality of characteristic curves related to the pressure measurement values and the inflow angles of the plurality of pressure gauges are obtained for each draft and each inflow angle, and the pressure measurements of the plurality of pressure gauges are obtained. A process for obtaining a ship speed against water based on a value, a density of water, and the plurality of characteristic curves; a process for obtaining an encounter pressure spectrum based on a measurement value of the pressure gauge; A process for obtaining an encounter wave spectrum based on a pressure frequency response function that is a function of a separately obtained wave encounter angle and the encounter pressure spectrum, the encounter wave spectrum, the speed against water, and the A wave characteristic measuring apparatus comprising: a control unit that performs processing for obtaining a wave spectrum based on a wave encounter angle. A first plurality of pressure gauges disposed at a position on the hull center line of the hull skin plate surface below the bow water surface and at a position that is substantially equidistant from the hull center line of port and starboard;
A second plurality of pressure gauges disposed respectively on the port and starboard of the ship;
A plurality of characteristic curves relating to pressure measurement values and the inflow angles of the first plurality of pressure gauges are obtained for each draft and for each inflow angle by a tank test or a theoretical calculation using a model ship, and the plurality of pressure gauges Of the water pressure based on the measured pressure value, the water density, and the plurality of characteristic curves, and the first plurality of pressure gauges are arranged at a position substantially on the center line of the hull. A process for obtaining a pressure cross spectrum based on the measured values of the pressure gauges and the measured values of the second plurality of pressure gauges, a pressure frequency response function using the water speed as a function, and the pressure cross spectrum And a control unit that performs a process for obtaining a directional wave spectrum based on the wave characteristic measurement apparatus.

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