JP4022580B2 - Apparatus and method for evaluating pressure response of liquid filled rigid container structure - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to an apparatus and method for evaluating a pressure response of a liquid-filled rigid container structure that contributes to the development of the container structure by appropriately evaluating the pressure response of a liquid-filled rigid container structure into which high energy is injected. More specifically, a liquid-filled rigid container structure for appropriately evaluating the pressure response of the rigid container structure when high-intensity charged particle beams are injected into the liquid inside from the outside of the container to contribute to the development of the container structure. The present invention relates to a pressure response evaluation apparatus and method.
[0002]
[Prior art]
There is a need to study the structural strength of rigid containers that receive or generate high-energy particle beams from the sun in outer space. In order to promote such research, it is preferable to manufacture a rigid test container and artificially prepare an environment in which particle beams are generated. In Europe, a neutron source development program ESS using a high-intensity proton accelerator is underway.
[0003]
When a large amount of scattered neutrons are generated by injecting a proton beam from the outside into a liquid metal sealed in a metal container and generating a large amount of scattered neutrons, a stress wave is generated in the container wall. At the same time, the temperature of the liquid that absorbs the other part of the incident energy rises momentarily and a shocking pressure wave is generated in the liquid. It is presumed that the two types of waves interact with each other on the wall surface to generate a new shock wave, and the two types of waves that are subsequently generated are added, so that repeated waves are generated periodically in the container.
[0004]
Such shock waves should cause cavitation in the liquid, and cavitation erosion should occur on the wall surface. Due to the synergistic effect of such a phenomenon and repeated stress, there is a possibility that the container will eventually be destroyed. In order to produce a container that can withstand such a severe environment, it is important to know the pressure response of the wall subjected to the shock wave.
[0005]
In order to measure the amount of displacement of an object that is displaced under pressure, a pressure sensor using a piezo element is commonly used. A Doppler interferometer is commonly used as a sensor for differentially knowing the speed change. Optical fibers are used to cause Doppler interference remotely in explosive environments. Although the piezo element is not useful in an environment where there are a large amount of drift electrons due to proton beam irradiation as described above, Doppler interference using an optical fiber can be measured safely even in an environment where a large amount of neutrons exist. Thus, a Doppler interferometer using an optical fiber may be used to enable dynamic pressure measurement in a container in the environment described above. That is, the possibility that the Doppler interferometer can be used to measure the pressure response of the heat input container structure in which high energy is instantaneously injected into the sealed liquid is recognized.
[0006]
[Problems to be solved by the invention]
The present invention has been made based on such a technical background, and achieves the following objects.
[0007]
An object of the present invention is to provide a pressure response evaluation apparatus for a liquid-filled rigid container structure and a method for evaluating the pressure response of a liquid-filled rigid container structure that enable measurement of the pressure response of the heat input container structure using a Doppler interferometer.
[0008]
Another object of the present invention is to provide a pressure response evaluation device for a liquid-filled rigid container structure and a method for evaluating the pressure response of a heat input container in which heat is input to both the container wall and the medium in the container. It is to provide.
[0009]
It is still another object of the present invention to provide a pressure response evaluation apparatus for a liquid sealed rigid container structure and a method for evaluating the pressure response of a heat input container that is exposed to charged particles.
[0010]
Still another object of the present invention is to provide a pressure response evaluation apparatus for a liquid sealed rigid container structure and a method for evaluating the pressure response of a heat input container having a large time density of injected energy.
[0011]
Still another object of the present invention is to provide a pressure response evaluation apparatus for a liquid-filled rigid container structure and a method for evaluating the pressure response of a heat input container having a large time density of energy to be injected by using a Doppler interferometer. There is.
[0012]
The more specific object of the present invention should become clearer through the embodiments.
[0013]
[Means for Solving the Problems]
In order to solve such problems, the pressure response evaluation apparatus and its evaluation method for a liquid-filled rigid container structure according to the present invention employ the following means. That is, a part of the container wall is designed to be displaceable (meaning displacement due to deformation). The amount of displacement of the displacement portion is designed to be at least one digit, preferably many orders of magnitude greater than the displacement due to expansion and contraction of the container itself. For example, the displacement portion is formed so that the wall of the container body is thinner or thinner. Alternatively, a part of the material of the container wall is made of a material that is more easily deformed than the other part.
[0014]
The substance enclosed in the container is a liquid. For example, a liquid metal. This liquid metal receives protons and emits neutrons. For this reason, the circumference | surroundings of a container are surrounded by the electron which is an anion.
[0015]
The container wall receives a shock wave on the inner surface. Stress waves are generated in the container wall itself. This stress wave is generated, for example, when a wall material absorbs a high-energy particle beam. The particle beam transmitted through the wall gives a gradient to the temperature of the liquid. This gradient occurs both in the energy beam injection direction (hereinafter referred to as the axial direction) and in a two-dimensional direction orthogonal to this direction (hereinafter referred to as the radial direction). The assumption that the amount of heat input decreases to a quadratic curve such as an ellipse in the radial direction and decreases exponentially in the axial direction well reflects the reality. This approximate expression is considered to be optimal as a reference expression for structure evaluation.
[0016]
The pressure wave and the stress wave interact with each other near the wall inner surface to generate a new wave. It is estimated that shock waves are repeatedly generated from the heat input region. Shock waves in the liquid are repeatedly reflected by the walls. A pressure wave having a repeating cycle gives an impact to the container wall. This impact is thought to cause cavitation erosion on the wall. If a pinhole occurs, it can begin to crack through the wall and eventually destroy the wall. A new stress wave is generated in the wall that has received the shock wave, and the destruction of the wall is promoted.
[0017]
The strength of the rigid container can be more accurately evaluated by analyzing the pressure response of the rigid container structure by analyzing the pressure wave than by analyzing the stress of the wall itself. Examination of the dynamic pressure of the displacement part and the correspondence of the container structure can increase the speed of container development. The displacement of the displacement portion can be obtained by calculation by integrating the displacement speed. The displacement speed can be measured by a Doppler interferometer. This measurement is possible even in an environment exposed to electrical particles, and the measurement is performed safely in a remote place where radiation is not received by using an optical fiber. The maximum displacement portion can be displaced by using a condensing lens. This makes it possible to measure the displacement of a specific point with high accuracy.
[0018]
The stress of the solid layer caused by the liquid layer of the solid / liquid coupled structure in which the solid layer and the liquid layer are continuously connected sharing a boundary surface is a theoretical equation that is a wave equation that treats both layers as one body. The stress of the solid layer can be obtained by offsetting the experimental value of the liquid layer contribution from the theoretical value of the stress obtained from the above. According to the present invention, the direct measurement of the stress of the solid layer is performed in an environment where direct stress measurement is not possible, such as a piezo element, and when it is desired to know the stress of a rigid body for which direct displacement measurement is difficult. Indirect measurement is effective.
[0019]
The pressure response measured in this way is made to correspond to the actual container structure. Many samples with such a response are available. This many samples form a reference row for determining the proper rigid container structure.
[0020]
【The invention's effect】
The apparatus and method for evaluating the pressure response of the liquid-filled rigid container structure according to the present invention enables the creation of a new evaluation standard by constructing the correspondence between the pressure response of the heat input rigid container structure and its strength and durability. The development of new containers.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of a pressure response evaluation apparatus for a liquid-filled rigid container structure according to the present invention will be described. FIG. 1 shows the first embodiment. A part of the container wall 1 of the rigid container described later is formed as a window member 2. The window member 2 can be formed integrally with the container wall 1 but can also be integrated with the container wall 1 by welding. The window member 2 has a perforated disk-shaped window member side rod 3. A screw hole 4 is formed at a plurality of locations in the window member side rod 3.
[0022]
The shaft portion 7 of the sensor body 6 is inserted coaxially into the window hole 5 that is the center hole of the window member 2. The sensor body 6 has a body side rod 8. The main body side rod 8 has bolt holes 9 at positions corresponding to the plurality of screw holes 4. A packing (not shown) is inserted between the opposing surfaces of the window member side rod 3 and the main body side rod 8. A plurality of bolts (not shown) can be passed through the bolt holes 9 and screwed into the screw holes 4 to attach and fix the sensor body 6 to the window member 2.
[0023]
The pressure receiving surface 11 that is the inner surface of the shaft portion 7 is formed on the same cylindrical surface or plane as the inner surface of the container wall 1. A hollow hole 12 that is closed from the outside is formed in the inner portion of the shaft portion 7. A displacement portion 14 having the reflecting surface 13 and the pressure receiving surface 11 which are the inner surfaces of the hollow hole 12 as front and back surfaces is formed as a part of the sensor body 6.
[0024]
The displacement portion 14 that completely blocks the liquid in the container wall 1 from the outside of the container can be considered to form a part of the container wall 1. The displacement portion 14 is designed to be at least one digit more than the displacement amount when the wall member 1 that receives the same pressure is deformed. That is, the displacement part 14 is a part which deform | transforms with respect to a container main body.
[0025]
One optical waveguide 15 is passed through the center axis of the sensor body 6 and fixed to the sensor body 6. As the optical waveguide 15, a commercially available optical glass fiber for communication is used as it is.
[0026]
The tip surface of the optical waveguide 15 is formed in a mirror surface that is perpendicular to the optical axis of the optical waveguide 15, that is, the center line. Alternatively, the laser can be condensed on the reflecting surface 13 by forming on the Fourier plane instead of the plane. It is preferable to form the reflecting surface 13 in a mirror surface (plane). The hollow hole 12 may not be a vacuum.
[0027]
The length of the optical waveguide 15 may reach several tens of meters. The other end of the optical waveguide 15 having this length is connected to the laser interference optical system 16. In order to detect the displacement amount or the displacement speed of the displacement portion 14, the laser interferometer is technically a Doppler interferometer. A Doppler laser interferometer is a conventional means for detecting the instantaneous velocity and acceleration of an object.
[0028]
FIG. 2 illustrates a Doppler laser interferometer. Since this is a known and commonly used means, the wavelength stabilized laser light source 21 is used as the light source. The laser beam emitted from the light source 21 is divided into two light beams by the first polarizing beam splitter 22, converged into one light beam by the total reflection prism 23 and reflected by the displacement portion 14, and is forwarded by the second polarizing beam splitter 24 in the return path. The interference light separated from the light enters the light receiver 27 as the intensity distribution light 25 and the signal light 26. One light beam 28 on the return path is modulated by an acousto-optic modulator 29. The optical waveguide 15 is used in the optical path portion 31 of FIG. The objective lens 32 is not essential.
[0029]
FIG. 3 shows a second embodiment of the sensor. The second embodiment differs from the first embodiment only in that a condensing Fourier lens 32 that is an objective lens is used. In this case, the point is on the reflecting surface 13.
[0030]
FIG. 4 shows an embodiment of a rigid container. The container wall 1 is formed of a cylindrical shell portion 41 and a hemispherical shell portion 42. A pair of hemispherical shell portions 42 are provided to face each other. For both the cylindrical shell portion 41 and the hemispherical shell portion 42, various types of SUS can be used as test pieces. The hemispherical shell portion 42 is formed to be thinner than the cylindrical shell portion 41. The thin hemispherical shell portion 42 thus formed is also called a window.
[0031]
The sensors described in FIG. 1 are provided at positions indicated by circles 43 and 44 in FIG. A metal liquid is enclosed in such a rigid container. A typical example of the metal liquid is mercury. As the charged particle beam, one extracted from an existing proton accelerator can be used. A dedicated accelerator is used to obtain the proton electron volts (eV / W) required to obtain unit watts.
[0032]
The incident direction of the charged particle beam is indicated by an arrow 45. This incidence establishes a heat input region 46 in the liquid. A physical quantity in an axisymmetric rigid cylindrical container can be expressed in cylindrical coordinates. The incident center line 47 is taken as the z axis. The z axis coincides with the center line of the cylindrical shell portion 41. An intersection point of the incident center line 47 and the hemispherical shell portion 42 is defined as an origin O. For the z-axis, the direction toward the inside is the positive direction. In the cylindrical coordinate system zr, r is a distance between a point on a plane orthogonal to the z axis and the z axis. The temperature of the liquid rises due to the irradiation of the particle beam. The heat input density Q (kcal, kilocalories / unit volume) can be considered to decrease in a quadratic curve, for example, an elliptic curve, in the radial direction, and decrease exponentially in the axial direction (z-axis direction), Approximately given by
[0033]
[Expression 1]
The macroscopic cross-section of mercury is 0.07 / cm for 1.3 GeV protons. FIG. 6 is a figure obtained by disassembling the previous equation into elements and visualizing them. The heat input density is maximized at the center position where z is smaller than 14 cm. When one pulse heat input is 60 kJ, the maximum temperature change ΔT is calculated from ΔT = Q (z, r) / Cρ (C is the specific heat of mercury, ρ is its density), and is about 50 degrees C.
[0034]
As shown in FIG. 5, such a temperature gradient generates a shock wave 48 in the liquid (in order to show that the waveform is a wave abstractly), and the shock wave 48 is quickly (about 1.5 km / s). ) Reach the wall surface and generate a stress wave 49 in the wall. At the same time, the instantaneous heat generation by the energy acquired by the hemispherical shell portion 42 which is a window generates a stress wave in the hemispherical shell portion 42.
[0035]
In order to develop a strong container structure, it is indispensable to feedback such mathematical analysis in the vicinity of the wall surface of these two pressure waves and stress waves and the experimental results. The present inventors are based on a one-dimensional wave basic equation relating to an arbitrary physical quantity (a wave equation in which a second partial derivative relating to spatial coordinates is equal to a second derivative relating to time coordinates), a one-dimensional beam (straight bar), a disc ( By conducting mathematical analysis for shell elements and solid elements with respect to (axisymmetric), it was confirmed that it is appropriate to use the above heat input density formula as a standard formula.
[0036]
Theoretical example:
The actual container has a liquid circulation loop for liquid cooling. Although the liquid has such a velocity, the flow velocity is much smaller than that of the time scale of stress wave propagation, so the liquid is treated as a stationary object. An example of the container has a thickness of 3.0 mm, a diameter of 20 cm, and a length of 40 cm. The internal fluid is modeled by a four-node solid element and the cylindrical container is modeled by a two-node shell element, and the coupled response between the solid metal container wall and the metal fluid is studied by this embodiment. The analysis results are as follows.
[0037]
An energy of 100 kJ per pulse is irradiated with a spatially wide proton beam as shown in FIG. Heat of 60 kJ is generated in the cylindrical region 46 of 10 cm, 10 cm, and 30 cm. The maximum value of the temperature rise of mercury is 47 degrees C, and the average temperature of the heat generating part is 16 degrees C. This temperature distribution is input as the node temperature of the finite element model shown in FIG. 6, and the generated and propagated stress is calculated. Here, when determining the node temperature, the parameters of the thermal input distribution function Q in the previous equation were λ = 6.5 cm and a = 1.77 cm.
[0038]
The temperature of the SUS304 material of the spherical shell portion that receives proton irradiation was obtained from Q (z, r) / (C · ρ) by dividing the exothermic temperature in the adjacent mercury by the specific heat and density of SUS304. As shown in FIG. 7, the evaluation points of stress generated in the shell element modeled on SUS304 are positions indicated by arrows in the drawing at z = 0, 0.1, 0.2, 0.3, and 0.4 m. Is a point. 8 and 9 show the state of stress waves propagating in the solid of SUS304. FIG. 8 shows a stress wave in the meridian direction, and FIG. 9 shows a circumferential stress wave perpendicular to the meridian direction. The meridian stresses point in the two nodal directions of the axisymmetric two-node shell element.
[0039]
As can be seen in FIGS. 8 and 9, at the point where z = 0, that is, the incident center on the hemispherical shell portion 42, both directions vibrated vigorously. The stress generated at this time was −200 to 600 MPa because the incident beam cross-sectional shape was axisymmetric, and the stress values in the meridian direction and the circumferential direction coincided. It turns out that it takes 0.22 ms until the stress wave arrives at the end of the SUS container with a certain time delay when it leaves the proton incident position in the z direction. Therefore, the influence of the reflected wave appears on the stress wave after 0.11 ms.
[0040]
In the meridian direction stress, the evaluation point excluding r = 0.4 m is −50 to 200 MPa, but at z = 0.4 m, the maximum value is doubled to 400 MPa. This indicates that the propagated stress wave is reflected at the container end, the phase is shifted 180 degrees, and the amplitude is doubled. On the other hand, the stress in the circumferential direction was -20 to 250 MPa before 0.11 ms, which overlaps with the reflected wave. The point that overlaps at the reflection end is the same as the meridian stress.
[0041]
It is not yet clear why the stress of z = 0 vibrates vigorously due to a calculation error or a dynamic vibration of the shell structure. At the point of z = 0.1 m, no large vibration is observed, and even if examined in detail, it is limited only to the shell element within the proton incident radius of 5 cm and does not seem to propagate as a stress wave. Therefore, there is a possibility that it is related to the natural vibration of the container. FIG. 10 shows the result of evaluating the stress acting on the container by Mises stress from the viewpoint of structural design.
[0042]
The maximum value other than z = 0.4 m was 200 MPa with z = 0.1 m within the range of the evaluation points. This suggests that the influence of reflected waves should be considered in the design of rigid structure containers. The stress waves shown in FIGS. 8 and 9 are superimposed on the propagation in the container solid and the pressure wave propagated in the liquid exerted on the container. In order to separate the effects of the two waves, FIGS. 11 and 12 show calculation examples when the temperature condition is kept as it is and there is no mercury.
[0043]
The intense vibration seen at z = 0 disappeared, but a slight vibration was seen after the stress reversed from compression to tension. It was found that when moving away from the proton incident point (0.1 <z), the stress wave became stable and the stress wave was generated at a period of about 0.1 ms. The range of the generated stress is −200 to 100 MPa at z = 0, and −50 to 50 MPa or less at other points. Compared with the results of FIGS. 9 and 10 carefully, the stress wave seen without mercury is It can be seen that they are superimposed. This is a characteristic of the coupled body.
[0044]
The diameter dependence of the rigid container was further investigated. Analysis was performed for three cases of container diameters of 150 mm, 200 mm, and 250 mm using the same temperature distribution and the same analysis model of FIG. FIG. 13 shows a comparison of the allowable maximum stress value with respect to the container diameter of the two most representative representative sites (window center and cylindrical part) in the rigid container design with respect to the beam pulse pressure wave. The design allowable stress of HT-9, one of the candidate materials for rigid containers, is described by Bauer (K. Skala, GS Bauer "On the pressure wave problem in liquid metal targets for pulsed-Spallation-Neutron-Souces" proc.ICANS -XIII, Switzerland, PSI-Proc. 95-02 (1995) p559-576), which is about 180 to 200 MPa in the region of operating temperature of 400 ° C. or less, which can be referred to at this time.
[0045]
Assuming that the high cycle component of the stress is an error in calculation for the window part, the container diameter may be about 250 mm or less than the allowable stress when evaluated with the low cycle component. Similarly, with respect to the container cylindrical portion, it is likely that the container diameter is about 250 mm or less than the allowable stress.
[0046]
In such an embodiment based on theoretical analysis, a safe rigid container can be produced only after comparison with actual experimental values. It is demanded that the response analysis of the solid-liquid complex is actually performed by a Doppler laser interferometer.
[0047]
In this specification, JAERI-Tech 97-037 published by Japan Atomic Energy Research Institute, “Structural evaluation of liquid metal target for neutron scattering facility (1st report)-Preliminary study of stress wave by proton beam pulse heat input” Created by reference to.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing an embodiment of a pressure response evaluation apparatus for a liquid-filled rigid container structure according to the present invention.
FIG. 2 is an optical circuit diagram showing a known example of a Doppler laser interferometer.
FIG. 3 is a front sectional view showing another embodiment of the pressure response evaluation apparatus for a liquid-filled rigid container structure according to the present invention.
FIG. 4 is a front sectional view showing an embodiment of a test container.
FIG. 5 is an oblique axis projection diagram in which a heat input density model is visually abstracted.
FIG. 6 is a cross-sectional view showing a visual abstraction of the generation of waves due to heat input.
FIG. 7 is a diagram for element analysis.
FIG. 8 is a graph showing time-varying waveforms of meridian direction stress waves;
FIG. 9 is a graph showing a time-varying waveform of a circumferential stress wave.
FIG. 10 is a graph showing a time-varying waveform of Mises equivalent stress.
FIG. 11 is a graph showing time-varying waveforms of meridian stress waves.
FIG. 12 is a graph showing a time-varying waveform of a circumferential stress wave.
FIG. 13 is a graph showing the maximum stress of a cylindrical container.
[Explanation of symbols]
1 container wall 2 window member 6 sensor body 11 pressure receiving surface 12 hollow hole 13 reflecting surface 14 displacement portion 15 optical waveguide 16 Doppler laser interference optical system 21 wavelength stabilization laser light source 32 objective lens 41 cylindrical shell portion 42 hemispherical shell portion 46 Heat input area Q Heat input density

Claims (8)

An optical waveguide for guiding the laser to irradiate the laser toward a displacement portion formed as a part of the container wall of the rigid container in which the liquid is enclosed;
Fixing means for fixing the distal end of the optical waveguide toward the displacement portion with respect to the displacement portion;
A Doppler interferometer for detecting the displacement velocity or the displacement amount of the displacement portion using the reflected light of the laser reflected from the displacement portion;
The reflected light is guided to the waveguide and returned to the Doppler interferometer,
A pressure wave generated in the liquid and a stress wave generated in the container wall interact with each other on the inner surface of the container wall, and the pressure exerted on the container wall by repeated shock waves is determined by the displacement speed of the displacement portion and A pressure response evaluation device for a liquid-filled rigid container structure that measures the displacement amount and evaluates the pressure response of the container structure. In claim 1,
A pressure response evaluation apparatus for a liquid-filled rigid container structure, wherein a Fourier lens is interposed between the displacement portion and the distal end of the waveguide. In claim 1,
The fixing means includes
A fixing portion for fixing the optical waveguide;
An apparatus for evaluating pressure response of a liquid-filled rigid container structure, comprising: a fixed part fixed to the container wall. A pressure response evaluation method for a liquid-filled rigid container structure for evaluating the pressure response of a container wall subjected to a strong pressure of shock wave from the inside by performing pressure analysis.
Forming a displacement portion that deforms under the pressure as part of the container wall, substantially enclosing a liquid in the container wall;
Injecting high energy into the liquid in the container to generate heat and shock waves in the liquid and simultaneously generate stress waves in the container wall;
A method for evaluating a pressure response of a liquid-filled rigid container structure, comprising: measuring a periodic displacement amount of the displacement portion using a Doppler interferometer. In claim 4,
The method for evaluating pressure response of a liquid-filled rigid container structure, wherein the high energy is injected semi-transparently from the outside of the container to the inside thereof. In claim 5,
The high energy is that of a particle beam;
The method for evaluating a pressure response of a liquid-filled rigid container structure, wherein the liquid is a metal. A pressure response evaluation method for a liquid-filled rigid container structure for evaluating the pressure response by analyzing the pressure of a container wall that receives a strong shock wave pressure from the inside.
A pressure wave generated in the liquid by heat input distribution in the liquid when energy is injected from outside the container;
A stress wave generated by receiving a part of the energy in the container wall during the injection;
Irradiating a laser from the outside to a displacement part that is deformed and deformed by receiving a pressure of a periodic repeated wave in the container due to a reflected wave generated between the liquid and the container wall;
The pressure fluctuation inside the unit body as one object formed from the liquid and the container wall is measured by measuring the displacement speed or the displacement amount of the displacement portion from the Doppler shift of the reflected light reflected by the displacement portion. A method for evaluating a pressure response of a liquid-filled rigid container structure. In claim 7,
The container is axisymmetric, and when a cylindrical coordinate system is set in which the z coordinate is a one-dimensional coordinate r on the axis perpendicular to the axial direction,
As the heat input density Q indicating the heat input distribution in the liquid, the following formula:

Is adopted as a reference formula for structural response evaluation. A pressure response evaluation method for a liquid-filled rigid container structure.

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