The method of modeling a power impact of internal waves on submerged object

 

(57) Abstract:

Usage: in modeling techniques in laboratory conditions force impact of internal waves on underwater technical objects. Essence: static components of force and torque effects of internal waves on podwodny technical object from the cover of his other water density with the passage of internal waves get in a small stratified hydrolate (tub) without wavemaker by immersion (uplift) and the inclination of the model to the appropriate internal waves magnitude. Dynamic components of the interaction is determined in the large pool with a homogeneous fluid with large models by awakening surface waves and ensure dynamic similarity numbers fruda, Reynolds, to remove the model from the layer jump of the density and the surface with subsequent separate from the translation of the static and dynamic components in nature. 2 Il.

The invention relates to the field of experimental fluid mechanics and applies modeling techniques in laboratory conditions force impact of internal waves on underwater technical objects.

There is a method of modeling of power and control is ratified and normal hydrolate, observing the magnitude of the geometric and kinematic similarity and similarity to difference in density between field conditions and laboratory stratified hydrolock.

The disadvantages of the known method is not accurate modeling of power effect of internal waves on underwater technical objects and large economic costs.

The purpose of the invention improve the accuracy of modeling the force impact of internal waves on underwater technical objects and reducing the economic costs of the experiment.

This objective is achieved in that the statistical components of the force Fyear Stand torque Myear Stimpact of internal waves on submerged object from the cover of his other water density with the passage of internal waves get in a small stratified hydrolate (tub), without the use of veleprodaja, by immersing and lifting model from a given horizon ATacutemTHEaboutnWITHLat distanceacutemTHECCmWITHLwhereBBmmove stratified fluid in situ on the horizon Iaboutyear Stis selected from the minimum acceptable accuracy up to 0.7 of the length of the tray, as well as the consistent form of the model on the corners of the trimmand rollmequal to the angle of wave slope of the internal wave on the horizon Iaboutnwith the construction according to Fyear St( Yacutem<N>pmand Myear St( YaboutacutemmmDynamic components interact to determine the other models are usually larger pool of homogeneous fluid through the awakening of surface waves with providing dynamic similarity Frodo and Reynolds, for which the scale of the model, its removal from the surface and parameters of surface waves are associated with the density distribution of the vertical in-situ conditions (removal of h1layer jump from the surface and h2from the bottom, tight top1and subscript2layers). Geometric scale model for simulation of viscous forces of nature are assigned near:

C where =n/1+ +cthkCCh the relative difference in density, taking into account the finite thickness of the top layer;

nthe density of water at selected th/BR>mthe same, in terms of the model experiment.

In Fig.1 schematically depicts a full-scale hydrological odds with the scheme of the model, provided the model experiment of Fig.2 scheme of the full-scale motion in the presence of disturbances ( dnmwhere Vnthe displacement field of the object).

Hydrostatic forces underwater technical object and internal waves are simulated with the described method in a small stratified hydraulic channels receive (baths), and hydrodynamic components in traditional homogeneous hydraulic channels receive large volnoproektorom using surface waves.

Such separate simulation is based on the fact that existing in nature differential 3 kg/m3(at the average density of 1025 kg/m3) of less than 0.3% density, the phase velocity of internal waves do not exceed 1 m/s This allows us to consider the static and dynamic forces of nature as independently existing. Static from the cover object, balanced on a horizon other water density due to the passage of the CENTURIES. Dynamic wave motion at the interface, which, as the removal from it is decreasing with the law is whether the bottom axis of the pycnocline,

yioremoval of the horizon, where the object is located, from the pycnocline.

In the simulation of power impact of internal waves on underwater technical object static components are determined or calculated, or when the model experiment in a small stratified hydrolate (tub) without wavemaker by immersing the model to a certain depth with different trim.

Dynamic components of the simulated internal wave with its frequency and length for any horizon of finding the object in their field is determined by load experiment in hydrodynamic pool with a homogeneous liquid when generating it surface waves. The parameters of these waves must satisfy the conditions of similarity: (1)

The criteria geometric and kinematic similarity in this case allows us to provide in experiments with surface agitation is much more significant speed towing models than in the stratified environment, and due to this to come out even at full-scale Reynolds number.

Let us consider the terms of modeling the dynamic part of the impact of internal waves on underwater technical object surface wave and Uslar>aboutCCcos ( KBBx +aBBt ) KCC=CC= , (2) where .

Profile of progressive surface waves on the horizon Io: cos(KCCX+APWt); KPW= , (3) wherePWl -KROothe attenuation of the amplitude of surface waves at deptho.

The General expression for the dynamic part of the power impact of internal waves on underwater technical object:

F= ACCCC2inincfV(1+K22)cosCCt kACCCC+sinCCt (4)

A similar expression for the dynamic part of the impact of surface waves on a fully submerged to the depthounderwater technical object has the structure

FDeanOlaAPWPW2pinV(1+K22)cosPWt kAPWPW+sinPWt (5)

Let internal unrest in nature and surface roughness in the model experiment like and observed large-scale relationship between the size of the underwater technical object and waves. In this case, will be equal pressure ratiosCCPWand the angles of the wave slopeCCaboutTOCCANDCCPWaboutTo
FCR= Same for in-situ conditions this force is easily calculated theoretically (under hypothesis A. N. Krylov), if you know the field of the wave pressures. Therefore, the practical interest is the transfer of model data on nature in relation to the inertial-wave and high-speed (damping) components.

When using the scale geometric similarity and With the introduction of the scale of the frequencies of the waves C= C-i0,5time and Ct= C-1C0L,5transforming the expression (4). At this field strength values minus the force of suction exerted through the geometric dimensions and values of the model variables in a homogeneous fluid from surface disturbances:

C nthe tab time you must submit aBBH=MVPC-L0,5and to stretch the process over time, for which tn= tmC (7).

Conditions of simulation of the viscosity forces cross flow underwater technical object without stroke internal waves and surface waves, is provided when ReBBM=ReMVP: BBH= MVP(8) allow us to determine the maximum, minimum scale of similarity, providing modeling the Reynolds: C= (9) for example, assumingnm2 kg / m3n1025 kg / m3BB250 m h180 m CLmin103

This means that the modeling power effects of internal waves on underwater technical object can be carried out in homogeneous hydraulic channels receive using surface waves on a relatively small models with respect to the similarity on the forces of viscosity. Since the distance from the boundary between the main contribution to the damping force contributes viscosity (friction and eddy components), the damping force in a more rational way to determine the impact on the model of the underwater technical object surface waves, shooting with the experimental curve FOLAin phases /2 and 3 /2, where the inertial-wave sostavlyajushie and model of Reynolds number and thereby dramatically improve the accuracy of high-speed components of the power impact of internal waves on underwater technical object, what is the main purpose of the present invention.

The order of implementation of the invention is as follows.

Accepted minimum scale models capable of modeling the Reynolds C= , so when

nm2 kg / m3n1025 kg / m3BB250 m h180 m CLmin103

Is the determination of the hydrostatic components of the force action of internal waves by testing the model on the load device in stratified tub with target values and h1at various horizons above the layer jump, in the layer jump. The stratification variables are measured synchronously with submersible model pornografa placed in alignment with it.

For cases, the longitudinal effects of internal waves on adopted levels of testing are performed for a range of pitch angles from 0 to 12o< / BR>
The model previously subject to the sign and experienced krizovany in fresh water. According to the results of static tests are based accordingm( U ) and FgSTM( U )

Accepted parameters of surface waves generation in homogeneous hydrolock on the basis of the similarity conditions

;

Proizvoditel model sunk to a depthaboutin terms of surface commotion specified parameters, recording the total hydrodynamic forces FOlamand characteristics of the excitement with two vynogradov: one placed at the level of calm water surface in the target model, and the second out of the stream relative to the first by the value of l smaller than the wavelength.

Processing of the experimental results this calculates the power of suction as the difference between the measured forces in phases 0 and Fmpp= Recalculates on the nature of the inertial-wave and s-components, obtained in a homogeneous fluid from the surface of excitement minus the force of suction on the nature of surface waves:

F= F(tmC3L,

To translate measured in the experiment forces in the natural time scale must submit theBBHMVPWITHLand to stretch the process over time, for which: tn=tmWITHL0,5< / BR>
Is determined by the total force of internal waves for nature by adding hydrodynamic components of FOWNIand static components of FGSTN(Y) obtained by the result of the, on the basis of dependencym( U ) and Fgstm( U )

Thus, with the use of small inexpensive stratified hydraulic channels receive no volnoproektorom and existing large marine basins can be obtained perturbing effect of internal waves on the model of underwater objects in compliance with the basic criteria of hydrodynamic similarity numbers froda and Reynolds.

Using the proposed method is already known hardware and respect in him the main criteria of similarity provides a lower cost and higher accuracy of the coefficients of the interaction model with internal waves.

The METHOD of MODELING a POWER IMPACT of INTERNAL WAVES ON SUBMERGED OBJECT, including conducting a laboratory experiment in stratified and conventional hydraulic channels receive with respect to the scale of the geometric and kinematic similarity and similarity to difference in density between natural conditions and in laboratory stratified hydrolate, wherein the statistical components of the force Fg:withtand torque Mg.withtimpact of internal waves in stratified hydrolate (tub) without using wavemaker by immersing and lifting model from a given horizon YmwithTr= YnaboutCLpin the distance

Yvaboutp= YvBBCLp,

where YvBB- move stratified fluid in natural conditions on the horizon Ynaboutfrom an imaginary axis of the layer of field spike density, and CLwithtpgeometric scale model for stratified hydrolock, the length of which is for a more precise definition of Fg.withtis selected from the minimum acceptable accuracy up to 0.7 of the length of the tray, as well as the consistent form of the model on the corners of the trimmand rollmequal to the angle of wave slope of the internal wave on the horizon Yyaboutwith the build dependencies Fyear St= (Yvaboutp, YvwithTrand Myear St(Yvaboutp,m,m), and dynamic components interact to determine the other models are usually larger pool of homogeneous fluid through the awakening of surface waves with providing dynamic similarity Frodo and Reynolds, for which the scale of the model, its removal from the surface and settings destruction of h1layer jump from the surface and h2from the bottom, the density of the upper1and subscript2layers), while the geometric scale model for simulation of viscous forces of nature are assigned near

< / BR>
where

< / BR>
the relative difference in density, taking into account the finite thickness of the top layer;

n- the density of water at the selected horizon finding object;

n- kinematic coefficient of viscosity of water in natural conditions;

m- the same, in terms of the model experiment.

 

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