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
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:
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
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.
FIELD: experimental hydromechanics; designing of equipment for conducting hydrodynamic and ice searches of marine engineering facility models in model testing basins.
SUBSTANCE: proposed device includes towing trolley with frame rigidly secured on it; this frame is provided with bar which is connected with model through dynamometers and bearing plate. Dynamometers form three-support force-measuring system; they are provided in each support in form of two interconnected elastic members; one elastic member is made in form of five-rod member provided with longitudinal and lateral force sensors; it is located between two flanges. Second elastic member of dynamometer is made in form of membrane-type elastic member whose membrane is located between rigid rim and rigid central part of this member provided with threaded rod with elastic hinge mounted over vertical axis perpendicularly relative to membrane. Membrane, rim and rigid central part with threaded rod and elastic hinge are made integral. Rim of membrane elastic members is rigidly connected with one of flanges of five-rod elastic member in such way that threaded rod is located along vertical axis of support and is rigidly connected via elastic hinge with bearing plate secured on model. Membrane is provided with resistance strain gages forming vertical force measuring bridge. Second flange of each five-rod member is connected with additional bearing plate secured on bar.
EFFECT: enhanced accuracy of measuring forces and moments.
FIELD: transport, auxiliary ship equipment.
SUBSTANCE: proposed test pool comprises the bottom simulation plant including submerged suspended support made up of assemblage of identical support sections arranged across the channel and distributed over its length. Aforesaid sections are suspended with adjusting tie-rods jointed to their length adjustment devices arranged on the channel walls sides. False bottom is mounted and rigidly attached to the said suspended support. The bottom simulation plant can vary the false bottom inclination towards horizontal plane in both the channel lengthwise direction α° till , and crosswise direction β° till , where L is the length of assembled bottom simulator, B is the bottom simulator width, HB is channel water depth, HD is the deepest bottom point, α° and β° are the angles of inclination of false bottom in lengthwise and crosswise directions, respectively. The total area of sections across the channel of support sections of the bottom simulator makes, at least, 0.05 of false bottom area in plan, while the false bottom width does not exceed 0.75 of the channel width. The false bottom is arranged in the channel symmetrically relative to the channel lengthwise axis.
EFFECT: higher efficiency of using ice test pool.
3 cl, 2 dwg
FIELD: testing equipment.
SUBSTANCE: invention is related to the field of shipbuilding, namely to technical means of experimental hydromechanics, and may be used for hydrodynamic tests of surface vessel model. Device comprises area of water with free surface, model of surface vessel towed by rope, motion of which is carried out through falling liquid weight that fills metering reservoir, which has holes both for reception and drain of liquid weight. Reservoir is fixed to axis of movable unit. Water to reservoir is sent through nozzle, which, together with elbow, crossbeam and bar creating bearing structure, and water pump, develop continuous water flow for reservoir filling. Fixed unit is attached to crossbeam, which produces polyspast together with unit. In process of tests performance, vessel model is positioned in the end of metering section of water area, and at the same time empty reservoir is lifted upwards. After contact with hole, reservoir after filling with liquid weight till rated level starts evenly lowering vertically down, providing for even horizontal motion of vessel model. The main result of experiment is time of weight lowering from unit down to support plate.
EFFECT: reduced cost of pool equipment, increased accuracy of performed measurements, reduced labour intensity of experiments performance.
3 cl, 1 dwg
SUBSTANCE: in trial tank, model, for instance platform is rigidly joined to dynamometre, which is fixed to base on tank board on the other side. Bottom imitator is installed under model and is rigidly suspended to base with the help of stands, which are located in stern part beyond model borders, ice field is frozen, which is then pushed up to model by means of towing trolley, and parametres of experiment are registered. Bottom imitator in its front part is fixed to base by means of stands, which pass through tested model. With the help of all these stands, clearance is adjusted and established between imitator and model, and tests are carried out. Device for realisation of such method in trial tank comprises towing trolley with bulldoser for ice pushing up to model, for instance platform, and rigid base fixed on tank board. Tested model is connected to it via dynamometre, as well as bottom imitator with the help of stands arranged in stern extreme end behind model. Imitator in front part has stands, which are joined to rigid base and pass through tested model of platform. It has wells arranged for specified stands. Stands have facilities for adjustment and installation of clearance between imitator of bottom and model, preferably lanyards, in process of tests performance.
EFFECT: invention makes it possible to improve reliability and accuracy of experiment results by provision of accurate positioning of imitator versus model.
2 cl, 1 dwg
FIELD: test engineering.
SUBSTANCE: invention refers to experimental studies in ice test pools and can be implemented for designing screw-steering complexes of vessels and facilities for their protection from ice by means of model experiment in pool under created conditions similar to natural. The procedure consists in preparing a field of model ice and in testing a model with operating propellers by means of towing the model or at its free motion at specified speed and at specified frequency of propeller rotation; testing consists in recording frequency of submerged ice cakes meeting a propeller-steering complex and other facilities external relative to the case of the model when ice protection of the model case is present or absent. Also density of model ice is measured. Further, the vessel model is towed in not destructed ice cover with turned off propellers and at speed determined by model-prototype relationship. There is measured average dimension of ice-cakes and width of channel behind the model formed at model passing through ice cover. Ice cover in not destructed ice field strip before the model, the width of which is equal to width of channel after the model, is cut into separate tightly adjoining blocks of ice. Dimensions of blocks are equal to measured average dimensions of ice cakes. The test is carried out in such made channel by means of towing the model with operating propellers. Notably, speed of model towing during the said test is less in comparison to model-prototype relationship speed determined with consideration of water and ice density. Frequency of propellers rotation is set to facilitate correspondence of speed of liquid in the stream behind the propeller to a value determined considering speed in the stream behind the propeller under natural conditions. During testing model under mode of free self-propelling rotation frequency of propellers is specified to ensure correspondence of speed of liquid in the stream behind the propellers under dockside mode to value determined with consideration of speed in the stream behind the propeller at dockside mode under natural conditions.
EFFECT: upgraded validity of test results by means of approaching them to natural conditions.
FIELD: testing equipment.
SUBSTANCE: invention is related to the field of experimental tests performance on models of ice breakers and ice ships in ice experimental pools. Method includes preparation of modeled ice field. Performance of model tests by means of its towing with a specified speed of vm. Registration of frequency of submerged ice debris ingress into propelling-steering complex, to ice boxes of ship model and to other external devices on model body with availability or absence of ice protection on model body. Density of modeled ice is identified as . In non-damaged ice cover they tow model of ship with a speed detected by ratio , where: νm and νf - speeds of model and full-sized vessels accordingly, λ is model scale. Average size of produced ice debris and channel width are measured behind model. In non-damaged ice field in front of vessel in width equal to width of channel behind model, ice cover is cut into separate adjacent ice floes. Size of ice floes equals measured average size of ice debris. Model towing in process of specified tests is carried out with speed ν'm, which is reduced in comparison with νm, which is identified by ratio ,
where: ρw - water density, - ice density required by technical task for performance of experiments.
EFFECT: provides for valid test results.
SUBSTANCE: method involves mounting a floating object model to the bottom of a tank through anchor connections and exposing the model to external wave effects and recording experiment parametres. The model under test is mounted to the bottom of the tank using two-branched flexible connection lines with which the model is movably joined through rollers freely hung to its housing. The paired branches of the flexible connection lines have different rigidity and the ends of the branches are attached to the base of the tank in points which are spaced apart. The device has truncated anchor connections through which the model under test is attached to the base of the tank. The anchor connections are in form of two-branched flexible connection lines between branches of which there are rollers mounted on the model, which are attached to its housing mainly on a flexible connection. The second branches of the flexible lines are also fitted with an elastic element, where the elastic elements of the paired branches of the flexible connection lines have different rigidity, and the other end of the branches of the said flexible lines is attached to the base of the tank at the corresponding point at a distance from the point of attachment of the first end.
EFFECT: approximation of simulated load in anchor connections to natural conditions.
3 cl, 2 dwg
SUBSTANCE: invention relates to ship building, namely, to safe operation of, mainly, gliding ships in shallow waters. Proposed method consists in optimising hydrodynamic characteristics of small-scale towed dynamically similar ship model in test pool in shallow depth prepared by using submerged screen and measuring model motion parameters. When model moves from deep water to shallow water, variations in draft and pitch angle are measured. This allows using experimental and computation procedures to define character of variations in position model hull bottom point at speed and at known tolerable depth for ship in shallow water and to evaluate ranges of safe speeds that make one of the basic elements in instructions for ships control in coastal navigation at water edges and in shallow waters.
EFFECT: possibility to define safe speed of ship model in move from deep water to shallow water.
FIELD: test equipment.
SUBSTANCE: invention refers to experimental flow dynamics of sea transport and deals with creation of laboratories for investigations of ice properties of ships. Ice experimental tank includes bowl with boards, handling dolly with equipment for water jets spraying at freezing of simulated ice cover. Outside the tank bowl parallel to one of its longitudinal boards there routed is a channel with the depth of not less than 0.5 m, which is interconnected with the bowl cavity via a pipeline. Perforated air supply tube to the channel is located at the channel bottom. Handling dolly is equipped with suction hydraulic pump for water supply to water jets spraying equipment, which is equipped with a connection pipe the receiving end of which is lowered into the above channel to the depth of not less than the half of its depth. Connection pipe of hydraulic pump is equipped with a rigid protective casing enclosing its housing and located so that it crosses free water surface in the channel and deepened with its lower end to the value of not less than 0.5 of the channel depth.
EFFECT: providing uninterrupted preparation of simulated ice for conducting the tests of ships models and engineering structures.
2 cl, 2 dwg
SUBSTANCE: invention relates to ship repair, particularly, to straightening of ship hull knuckle. Proposed method comprises measuring ship draught by all deadweight scales for ship fully loaded and empty. Results obtained allow calculating residual knuckle of the ship. Ship upper element cutting line is traced. Ship is placed in dock on dock floor to measure hull knuckle. Not here that hull center gives under gravity to reduce knuckle and eliminate clearances in supports pressed loosely to hull. Ship upper elements are cut along traced line. Cut edges at compressive stress converge. After convergence said edges are fitted in and welded together. Ship is launched and residual knuckle is measured to be eliminated, is required, by repetition of above jobs.
EFFECT: increased dead weight.