CN105021791A - Method and device for simulating variable roughness factor ice cover in ice water dynamic test - Google Patents

Abstract

The invention relates to a method and device for simulating a variable roughness factor ice cover in an ice water dynamic test. The device comprises a simulated ice cover plate which is matched with a simulated river course is width, the simulated ice cover plate is made of polyethylene boards, multiple fixing holes are formed in the simulated ice cover plate uniformly, rough blocks for simulating the roughness factor are fixed in the fixing holes correspondingly according to test requirements, and the rough blocks are made of polyethylene bars. According to the method and device, the ubiquitous material, namely the polyethylene, serves as the material for simulating the ice cover, the ice cover plane is simulated by boards, the long-strip-shaped polyethylene materials are erected on the board for simulating the rough surface of the ice cover, and simulated ice covers of different roughness factors are formed. Due to the fact that the long-strip-shaped materials which are different in length and density can be replaced in various simple ways, the ice covers of different roughness factors can be simulated, the test can be accelerated, and the test cost can be reduced greatly.

Description

Variable roughness ice sheet analogy method and device in a kind of frozen water dynamic test

Technical field

The present invention relates to variable roughness ice sheet analogy method and device in a kind of frozen water dynamic test, is a kind of hydraulic test method and apparatus, is a kind of method and apparatus of frozen water dynamic experiment.

Background technology

After entering the winter, temperature reduces, and water body loss of heat, when water temperature is down to below 0 DEG C, just can produce frost flower in river course, and along with water body constantly loss of heat, water surface occurs floating ice further.Affect by flow condition, topographic condition and wind direction etc., the floating ice of water surface mutually can be piled up and form ice, and the existence of ice sheet can substantially increase wetted perimeter and resistance, even if the constant remarkable reduction that also can cause river course discharge capacity of discharge section area.Because the field prototype measurement of ice condition has certain danger, therefore the important means that modeling effort becomes frozen water dynamics research is carried out in room by experiment.Experimental simulation research nature relates to the problem of modelling of ice sheet and ice sheet roughness.Roughness is the integrated coeficient of the factor such as the roughness on irregular, the border weighing limit wall shape and neat degree, is the important parameter in frozen water mechanics study.The ice sheet analogue technique mainly artificial slotting bamboo let on cystosepiment that current laboratory is conventional, the degree of roughness of artificial increase cystosepiment, the degree of depth and the density of inserting bamboo let because artificial are difficult to control, therefore the method randomness in the control of ice sheet roughness is comparatively large, brings difficulty to regular campaign.And if the Density Distribution of bamboo let is uneven, causes the velocity flow profile of testing section uneven, affect experimental precision, even accuracy.

Summary of the invention

In order to overcome the problem of prior art, the present invention proposes a kind of for the variable roughness ice sheet analogy method in frozen water dynamic test and device.Described method provides a kind of ice sheet and roughness analogy method thereof, can need adjustment roughness degree according to different, and reusable.

The object of the present invention is achieved like this: variable roughness ice sheet analogy method in a kind of frozen water dynamic test, described method uses polyethylene board as the material of simulation ice sheet, coarse piece of many long axis directions strip vertical with board plane is arranged in the one side of described polyethylene board, utilize coarse piece that length length is different, and various different roughness bottom the different arrangement mode simulation ice sheet of coarse piece of density.

A kind of variable roughness ice sheet analogue means according to described method design, comprise the simulation ice sheet plate adapted with simulating riverway width, the material of described simulation ice sheet plate is polyethylene board, the multiple fixed orifice of uniform distribution on described simulation ice sheet plate, need coarse piece of fixed-analog roughness in described fixed orifice according to test, the material of described coarse piece is polyethylene bar.

Further, the fixed orifice on described simulation ice sheet plate is for being staggered.

Further, fixed orifice on described simulation ice sheet plate is manhole, described coarse piece of being is the circular bar that diameter and fixed orifice adapt, one end of described circular bar is fixed with the disk that a diameter is greater than bar diameter, and described disk is removably connected by fixation means and simulation ice sheet plate.

Further, described fixation means is the pressing plate be threaded with simulation ice sheet plate, and described disk is clipped between simulation ice sheet plate and pressing plate.

The beneficial effect that the present invention produces is: the present invention adopts this very general material of tygon as the material of simulation ice sheet by theory calculate, and use sheet material to simulate ice sheet plane, and use the polythene material of strip to stand on sheet material, the rough surface of simulation ice sheet, forms different roughness simulation ice sheet.Various simple mode can be used to change length difference owing to using, the strip material that density is different, the ice sheet of various different roughness can be simulated with this, the cost of experiment is reduced greatly, use simple substitute mode, significantly can also reduce the non-cutting time of experiment, the various requirement namely meeting experiment also ensure that the precision of experiment simultaneously, accelerate test speed, and cost is then obviously declined.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the invention will be further described.

Fig. 1 is the structural representation of device described in embodiments of the invention two;

Fig. 2 is staggered fixed orifice schematic diagram described in embodiments of the invention three;

Fig. 3 is the schematic shapes of described in embodiments of the invention four coarse piece;

Fig. 4 is apparatus structure schematic diagram described in embodiments of the invention five.

Embodiment

Embodiment one:

The present embodiment is variable roughness ice sheet analogy method in a kind of frozen water dynamic test, described method uses polyethylene board as the material of simulation ice sheet, coarse piece of many long axis directions strip vertical with board plane is arranged in the one side of described polyethylene board, utilize coarse piece that length length is different, and various different roughness bottom the different arrangement mode simulation ice sheet of coarse piece of density.

The foundation of method described in the present embodiment is:

1, the selection gist of ice sheet simulation material:

The frozen water dynamic experiment demand fulfillment prototype in laboratory is similar with the floating ice movement of model, that is:

${\left(\frac{V}{\sqrt{2g\frac{{\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i}{{\mathrm{\ρ}}_w}t}}\right)}_p={\left(\frac{V}{\sqrt{2g\frac{{\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i}{{\mathrm{\ρ}}_w}t}}\right)}_m$

$\frac{{\left(V\right)}_p}{{\left(V\right)}_m}=\frac{\sqrt{{\left({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i\right)}_p{t}_p}}{\sqrt{{\left({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i\right)}_m{t}_m}},{\left(V\right)}_r=\sqrt{\frac{{\left({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i\right)}_p}{{\left({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i\right)}_m}{t}_r}$

That is:

${\left(L_r\right)}^{1/2}=\sqrt{\frac{{\left({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i\right)}_p}{{({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i)}_m}}\sqrt{\left(L_r\right)},{({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i)}_p={({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_i)}_m$

(ρ _i) _p＝(ρ _i) _m

In formula: subscript p represents prototype, subscript m represents model, and subscript r represents guide; V is flow velocity; G is acceleration of gravity; ρ _wfor the density of water; ρ _ifor the density of ice; T is ice thickness.

Above formula shows the equal density of ice in floating ice movement requirement of similarity prototype and model.Because the density of ice is about 917kg/m ³, therefore the present embodiment adopts density to be 920kg/m ³the tygon material of simulating as ice sheet, density meets the similarity requirement needed for frozen water dynamic experiment.

2, the simulation of ice sheet roughness n:

Current flowing in river all meets energy equation

$Z_1+\frac{P_1}{\mathrm{\γ}}+\frac{V_1^2}{2g}=Z_2+\frac{P_2}{\mathrm{\γ}}+\frac{V_2^2}{2g}+h_w$

Z in formula ₁and Z ₂be respectively the elevation of upstream and downstream section, P ₁and P ₂be respectively the pressure of upstream and downstream section, V ₁, V ₂be respectively the mean flow rate of upstream and downstream section, h _wfor the loss of flood peak.

From above formula, the isoparametric calculating of the water level in river, flow all needs first to determine loss of flood peak h _wthis parameter, and loss of flood peak h _wexpressed by roughness n.

At hydraulically rough region, thank to just coefficient C only relevant to the R/ Δ of reflection relative roughness.And in rough region, $C=18\lg \left(\frac{12.2R}{\mathrm{\Δ}}\right),$ Again $C=\frac{1}{n}{R}^{1/6},$ Then roughness coefficien n can be expressed as

$n=\frac{R^{1/6}}{18\lg \left(\frac{12.2R}{\mathrm{\Δ}}\right)}=\frac{R^{1/6}}{19.55+18\lg \left(\frac{R}{\mathrm{\Δ}}\right)}$

In formula, R is hydraulic radius, and △ is absolute roughness height.

From above formula, when the hydraulic radius of river cross-section is constant, roughness and the absolute roughness height △ of ice sheet have direct relation, therefore in frozen water dynamic test, provide the ice sheet of different roughness height to become the main path of ice sheet roughness simulation.

Based on above-mentioned theoretical analysis, the present embodiment uses polyethylene board as the material of simulation ice sheet, and arrange coarse piece of many strips in the one side of sheet material, the material of coarse piece is all tygon.The length direction axis of coarse piece and simulation ice pressing plate material plane orthogonal, simulate the roughness bottom ice sheet with this.Preferably can dismantle very easily or be arranged on simulation ice sheet plate for these coarse piece.By coarse piece and different arrangements of different length, and the density of arrangement, form the analogue means of the various different roughness of simulation.

Embodiment two:

The present embodiment is a kind of variable roughness ice sheet analogue means of method design according to embodiment one, as shown in Figure 1.The present embodiment comprises the simulation ice sheet plate 2 adapted with simulating riverway 1 width, the material of described simulation ice sheet plate is polyethylene board, the multiple fixed orifice 201 of uniform distribution on described simulation ice sheet plate, need coarse piece 3 of fixed-analog roughness in described fixed orifice according to test, the material of described coarse piece is polyethylene bar.

The material of the present embodiment using polyethylene board as simulation ice cube, the ice cube of analog board bulk is floating or cover on the water surface.According to the calculating of embodiment one, density and the ice of polythene material are close, and therefore, polyethylene board completely can the ice cube floating state on the water of analog board bulk, comprise with the floating travelling speed of current and the amplitude etc. that moves up and down with wave.

Device described in the present embodiment is mainly applied to and carries out ice sheet experiment in the tank of simulating riverway.The size of simulation ice sheet plate is determined as required, its width can be in the same size with the width of the tank in simulation river, adapt in other words conj.or perhaps, its length then needs to determine according to the time, as: experimental needs intercept the simulation ice sheet plate of 5 meters long 1.2 meters wide in the tank of 10 meters long 1.2 meters wide, as length and the width of Experiment on Function sheet material.Described adapting refers to that the width dimensions of simulation ice sheet plate and tank is in the same size, but the width of simulation ice sheet plate is more slightly smaller than the width of tank, to simulate ice sheet plate putting into tank, and keep certain interval with tank both sides side board, simulation ice sheet plate can be swum on the water surface, and can rise and fall with the fluctuating of the water surface, too can not be stuck close to tank with because of size.In this case, simulation ice sheet plate, should Constrained in water (flow) direction, and conveniently method arranges in the downstream of simulation ice sheet plate the point of fixity that stops ice sheet plate flow further downstream, namely can achieve the goal.And need to simulate the ice sheet be frozen on river course in some experiments, then need simulation ice sheet plate to be fixed on simulating riverway, its height is identical with water level.Fixing mode can the various fixing means of flexible Application.

According to embodiment one go out calculate, be simulation ice bottom roughness, the present embodiment takes coarse piece of strip, and the material of coarse piece also should be tygon.Coarse block of can be cross sectional shape be circular bar also can be cross sectional shape is other shape bars of square or other regular polygons.

The object that simulation ice sheet plate is beaten fixed orifice be determine coarse piece in the upper position of simulating ice sheet plate, fixed orifice can be through hole also can be blind hole.The arrangement on simulation ice sheet plate of fixed orifice can be the array type arrangement alignd in length and breadth, or vertical alignment traversed by is wrong or staggered staggered arrangement is indulged in horizontal alignment, also can be other shapes arrangements such as the outside radiation arrangement in center.

Use different coarse tile heights and arrange that density can simulate different absolute roughness heights.The length (highly) of coarse piece experimentally roughness need intercept, use different coarse block lengths (highly) and layout density can simulate different absolute roughness heights.Need the roughness of simulation larger, then the length of the strip material intercepted is longer, otherwise then shorter.The bar that many intercept is fixed on the one side of simulation ice sheet plate, and faces down with one of fixing bar, the one side of not fixing bar upwards, makes bar insert in water, forms the form of simulation ice cube.Fixing how many coarse piece, and the density degree of coarse piece is also relevant with roughness.More than coarse piece, more intensive, then roughness is larger, otherwise less.The present embodiment takes the mode opening many fixed orifices on simulation ice sheet plate uniformly, in each fixed orifice, fix coarse piece by dismountable mode.Multiple coarse piece that preparation length is different, the length of coarse piece required for roughness computed in advance, quantity, density degree, selectively coarse piece is fixed in each fixed orifice of simulation ice sheet plate, that is: or in institute is porose coarse piece (roughness is maximum) is fixed, or hole, one, interval is fixed coarse piece (roughness takes second place), or Liang Ge hole, interval fixes one coarse piece etc.

Therefore, the connection between coarse piece and simulation ice sheet plate should be removably connect very easily.Connection between coarse piece and simulation ice sheet plate can have various ways.As: adopt and be threaded, screw connection etc.One connected mode very ingenious can also be used: by fixed orifice for beat as through hole, be T-shaped by each coarse blocks design, namely as bolt, a stub end is set at columniform one, when columniform main body is through fixed orifice, stub end limits columniform main body through fixed orifice.Meanwhile, stub end is designed to disc, uses a block pressur plate to coordinate with simulation ice sheet plate, the stub end of disc is clamped, makes whole coarse piece can not deviate from from fixed orifice, can not rock, play fixing effect.And pressing plate can be designed as and simulates ice sheet plate size and adapt, coarse piece that a block pressur plate can be pushed down insert in all fixed orifices.Certainly, the material of pressing plate also should be polyethylene board.

The ingenious part of fixing coarse piece is like this: only need limited several screws to fix between pressing plate and simulation ice sheet plate, no matter there be how many coarse piece, as long as insert in fixed orifice simple, limited several screws of screwing on just secure all coarse piece.This will facilitate many compared with coarse piece of being screwed one by one one by one.This point is very important in an experiment, because will constantly simulate various roughness in an experiment, and various coarse piece different in size of constant permutation and combination.Use above-mentioned mode can save a large amount of experiment non-cutting times, improve conventional efficient.

Embodiment two:

The present embodiment is the improvement of embodiment one, is the refinement of embodiment one about simulation ice sheet plate.Fixed orifice on simulation ice sheet plate described in the present embodiment for being staggered, as shown in Figure 2.

Simulation ice sheet plate is used for the fixed block of fixing coarse piece, the present embodiment is taking a kind of adjacent hole alternative arrangement mode, coarse piece of density enlarged relative of relative current (in Fig. 2 arrow A direction) upstream face, the object of staggered perforate is reached: namely use highly less coarse piece also can obtain larger roughness (relative to alignment in length and breadth), while saving material, also can reduce the coarse piece of impact on current fluidal texture with this.

Embodiment four:

The present embodiment is the improvement of above-described embodiment, is that above-described embodiment is about the refinement of simulation ice sheet plate with simulation coarse piece of combination.Fixed orifice on simulation ice sheet plate described in the present embodiment is manhole, described coarse piece of being is the cylindrical bar that diameter and fixed orifice adapt, one end of described bar is fixed with the disk that a diameter is greater than bar diameter, and described disk is removably connected by fixation means and simulation ice sheet plate.

Pole and circular hole are the shapes of the most easily processing, the fixed orifice described in the present embodiment and coarse piece of use circle, and pole section bar and circular hole are the most easily processed, and can save the expense of experiment, reduce costs.

Coarse piece of described diameter with the implication that fixed block diameter adapts is: the nominal diameter of coarse piece is equal with the nominal diameter of fixed orifice, but tolerance is distinguished to some extent, the diameter of coarse piece of diameter is slightly a little bit smaller, and the diameter of fixed orifice is micro-greatly a bit, make coarse piece can insert in fixed orifice very smoothly.

As shown in Figure 3, the cylindrical bar 302 of coarse piece is main body to the shape of coarse piece, and columniform one end is fixedly connected with a disk 301, and formed " major part ", the axial cross sectional shape of whole coarse block length is T-shaped.

The fixing enforcement be fixed on coarse piece on simulation ice sheet plate can have a variety of, as: fixing enforcement is a primary screw, the disk at coarse piece of top and simulation ice sheet plate is tightened, that is: each coarse piece is fixed on simulation ice sheet plate with a primary screw.But this fixed form has a problem, screw is too many, likely affects the proportion of whole device, the precision of impact experiment.Also the mode of the pressing plate as described in embodiment one can be used.

Embodiment five:

The present embodiment is the improvement of above-described embodiment, is the refinement of above-described embodiment about fixation means.Fixation means described in the present embodiment is the pressing plate 4 be threaded with simulation ice sheet plate, and described disk is clipped between simulation ice sheet plate and pressing plate.

The surrounding of simulation ice sheet plate arranges screw 5, for pressing plate being fixed on simulation ice sheet plate.During use, T-shaped coarse piece is placed in the hole of simulation ice sheet.The effect of pressing plate clamps coarse piece together with simulation ice sheet plate, makes it fixing, make it can not be subjected to displacement with the motion of current in process of the test.If coarse piece is shaken with the motion of current, ice sheet roughness will be caused to change, therefore, fixing coarse piece, avoid rocking very important.Simulation ice sheet, coarse piece and pressing plate are fixed together by the set bolt of corner during use, putting into tank can test, as shown in Figure 4.

The material of described pressing plate also should be polyethylene board, to meet the requirement of proportion.The benefit that of this fixed form is very large is, use limited several screws, the proportion affecting normal appts is very little, that is very little to the Accuracy of whole experiment.

Pressing plate can use poly reticular lamina, as long as former of the top can pushing down coarse piece.

Finally it should be noted that, below only in order to technical scheme of the present invention to be described and unrestricted, although with reference to preferred arrangement scheme to invention has been detailed description, those of ordinary skill in the art is to be understood that, can modify to technical scheme of the present invention (shape of such as tank and analogue means, each annexation and mode etc.) or equivalent replacement, and not depart from the spirit and scope of technical solution of the present invention.

Claims (5)

1. variable roughness ice sheet analogy method in a frozen water dynamic experiment, it is characterized in that, described method uses polyethylene board as the material of simulation ice sheet, coarse piece of many long axis directions strip vertical with board plane is arranged in the one side of described polyethylene board, utilize coarse piece that length length is different, and various different roughness bottom the different arrangement mode simulation ice sheet of coarse piece of density.

2. the variable roughness ice sheet analogue means of a method design according to claim 1, it is characterized in that, comprise the simulation ice sheet plate adapted with simulating riverway width, the material of described simulation ice sheet plate is polyethylene board, the multiple fixed orifice of uniform distribution on described simulation ice sheet plate, need coarse piece of fixed-analog roughness in described fixed orifice according to test, the material of described coarse piece is polyethylene bar.

3. device according to claim 2, is characterized in that, the fixed orifice on described simulation ice sheet plate is for being staggered.

4. device according to claim 3, it is characterized in that, fixed orifice on described simulation ice sheet plate is manhole, described coarse piece of being is the circular bar that diameter and fixed orifice adapt, one end of described circular bar is fixed with the disk that a diameter is greater than bar diameter, and described disk is removably connected by fixation means and simulation ice sheet plate.

5. device according to claim 4, is characterized in that, described fixation means is the pressing plate be threaded with simulation ice sheet plate, and described disk is clipped between simulation ice sheet plate and pressing plate.