Patent Application
20210122129
This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2019-0134999, filed on Oct. 29, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.
The following disclosure relates to a method of manufacturing an orifice and an orifice manufactured by the same, and more particularly, to a method of manufacturing an orifice capable of smoothly realizing desired pressure and flow rate conditions even in environmental conditions of which implementation is difficult, such as ultra-high pressure and low flow rate conditions, and an orifice manufactured by the same.
An orifice is a device provided on a channel through which a fluid flows and adjusting a pressure and a flow rate of the flowing fluid. In principle, the orifice is configured to adjust the pressure and the flow rate by changing a channel resistance of the channel through which the fluid flows. Generally, the orifice has the simplest form of realizing this principle, and has a form in which a vent hole is formed in a plate installed to block the channel. Alternatively, the orifice has a form in which a capillary tube having a small diameter and a large length enters the middle of the channel.
Meanwhile, currently, Korean space launch vehicles use an engine that uses liquid oxygen as an oxidant. Since such an engine may be stably ignited in a state where it is cooled to a level similar to the liquid oxygen, an oxidant recirculation process of cooling the engine and components such as pipes connected to the engine by allowing the liquid oxygen present in an oxidizer to flow to an engine main pipe is performed before the engine of the launch vehicle is ignited. The oxidant recirculation process will be described in more detail. The liquid oxygen is circulated to the engine until the engine is sufficiently cooled through a closed loop including a supply line supplying the liquid oxygen from the oxidizer tank to the engine and a circulation line returning the liquid oxygen from the engine to the oxidizer tank. In this case, a small amount of helium gas is injected and sprayed into the circulation line so that the liquid oxygen may more smoothly return to the oxidizer tank. By spraying the helium gas into the circulation line, a flow of the liquid oxygen returning to the oxidizer tank is further activated by kinetic energy and buoyancy of the helium gas, such that a recirculation flow may be more smoothly performed.
The helium gas used in the oxidizer recirculation process has ultra-high pressure and very low temperature states of about 22 MPa and 90K (−183° C.), and a flow rate of the helium gas supplied to the circulation line is appropriately about 1 g/s. In order to spray a fluid having an ultra-high pressure and a very low temperature by a very small amount, a design in which an orifice having a very small hole whose diameter is about 0.1 mm needs to be used is derived. However, it is very difficult to manufacture such a small orifice, and it is likely that the orifice will be blocked by foreign materials due to the very small diameter. Particularly, it is likely that ice particles will be generated due to a small amount of residual gas such as carbon dioxide or moisture included in the pipe or helium gas in a very low temperature environment, and a risk that the orifice will be blocked by such ice particles is further increased.
When it is not smooth for a single orifice to spray a fluid having a high pressure by a low flow rate, a multi-stage orifice in which a plurality of orifices are arranged in series is used or an orifice having a capillary pipe form is used. Korean Patent Registration No. 1778118 (entitled “Steam Generator of Printed Circuit Heat Exchanger Type Having Orifice and filed on Sep. 14, 2017) discloses a technology in which a pressure and a flow rate are adjusted using a multi-stage orifice implemented by a concave-convex structure formed on a channel using a chemical etching method, and Korean Patent Registration No. 1831303 (entitled “Viscometers and Method of Measuring Liquid Viscosity” and filed on Feb. 14, 2018) discloses a technology of adjusting a pressure and a flow rate using a long capillary tube.
However, even with such multi-stage orifice or capillary pipe, in order to realize all of the ultra-high pressure, very low temperature, and very low amount conditions, the number of stages or a length of the capillary pipe is excessively increased, which may cause other problems. Actually, a multi-stage orifice manufactured in a form in which twenty orifices having a hole diameter of 0.5 mm are arranged in series has been currently used in an oxidizer recirculation line of the launch vehicle described above. It has been known that an entire length of the multi-stage orifice is about 200 mm, an entire diameter of the multi-stage orifice is about 50 mm, and a weight of the multi-stage orifice is about 1 kg. In a case of using such a multi-stage structure, hydraulic performance can be satisfied, but a problem that a volume and a mass of an orifice component itself are excessively increased occurs. In a case of using an orifice having a capillary pipe form, a length of the capillary pipe is significantly increased, such that a volume increase problem becomes more serious. Particularly, in a case of the launch vehicle, the necessity to reduce a volume and a mass of each component is very high, and such an excessive volume and mass increase problem needs to be solved.
1. Korean Patent Registration No. 1778118 (entitled “Steam Generator of Printed Circuit Heat Exchanger Type Having Orifice and filed on Sep. 14, 2017)
2. Korean Patent Registration No. 1831303 (entitled “Viscometers and Method of Measuring Liquid Viscosity” and filed on Feb. 14, 2018)
An embodiment of the present invention is directed to providing a method of manufacturing an orifice capable of spraying a very small amount of fluid in ultra-high pressure and very low temperature environments and reducing a volume and a mass, and an orifice manufactured by the same. More specifically, an embodiment of the present invention is directed to providing a method of manufacturing an orifice capable of manufacturing an orifice effectively realizing a desired hydraulic performance by a simple manufacturing method of allowing a channel region having a cross section close to a rectangular shape to be formed by pressing a part of a capillary pipe, and an orifice manufactured by the same.
In one general aspect, a method of manufacturing an orifice includes: a body portion preparing step of preparing a body portion in which a hollow having a circular cross section is formed; a stress value calculating step of calculating a stress value required for a predetermined desired flow rate value according to the following relationship equation: {dot over (m)}=C1 exp(C2S) (here {dot over (m)}: Flow rate, S: Stress, C1: Positive constant, and C2: Negative constant) between a flow rate and a stress; and a pressed portion manufacturing step of manufacturing a pressed portion in which the hollow becomes a slit by pressing at least a partial region of the body portion with a pressing force corresponding to the stress value calculated in the stress value calculating step.
In the stress value calculating step, values of C1 and C2 may be determined by at least one selected among an outer diameter, a thickness of a wall, and a material of the body portion.
In the pressed portion manufacturing step, an area value of the pressed portion may be calculated according to the following relationship equation: A=WL=(2t+ΠDi/2)L (here, A: Area of pressed portion, W: Width of pressed portion, L: Length of pressed portion, t: Thickness of wall of body portion, and Di: Inner diameter of body portion), and the pressing force value may be calculated from the following relationship equation: F=SA (here, F: Pressing force, S: Stress, and A: Area of pressed portion).
In another general aspect, an orifice is an orifice 100 manufactured by the method of manufacturing an orifice as described above, includes: the body portion 110 in which the hollow 111 through which a fluid passes and which has the circular cross section is formed; and the pressed portion 120 formed by pressing at least the partial region of the body portion so that the hollow 111 becomes the slit 121.
The pressed portion 120 may be formed in a region between both ends of the body portion 110. The pressed portion 120 may be formed from one end portion of the body portion 110 to the other end portion of the body portion 110.
The body portion 110 may have a linear shape. Alternatively, the body portion 110 may have a non-linear shape.
Here, a method of manufacturing an orifice according to the present invention and an orifice manufactured by the same having the configuration as described above will be described with reference to the accompanying drawings.
Basic Configurations of Orifice and Method of Manufacturing the Same According to the Present Invention
In addition, the pressed portion 120 may be formed in a region between both end portions of the body portion 110, that is, a partial region, as illustrated in
A basic configuration of a method of manufacturing the orifice 100 will be briefly described below.
That is, in short, a portion of a raw material formed in a general capillary pipe shape, that is, a circular tube shape having the hollow 111 through which a fluid passes and which has the circular cross section is pressed, such that a pressed region becomes the pressed portion 120 and the remaining region that is not pressed and maintains an original shape becomes the body portion 110. As a shape of the pressed portion 120 becomes a flatly pressed shape, the hollow 111 in a region corresponding to the pressed portion 120 is also flatly pressed in a pressing process even though it originally has the circular cross section, such that the hollow 111 becomes the slit 121 having a cross-sectional shape close to a rectangular shape that is thin and elongated.
The slit 121 manufactured in the rectangular cross-sectional shape that is thin and elongated as described above becomes an element serving to control a fluid pressure and a flow rate of the orifice 100. As well-known, the orifice changes a speed and a flow rate by increasing a channel resistance using a structure in which a channel shape is rapidly changed in principle. Also in the orifice 100 according to the present invention, when a fluid flows through the hollow 111 formed in the body portion 110 and having the circular cross section and then flows to the slit 121 formed in the pressed portion 120, a channel shape, a channel cross-sectional area, and the like, are changed, such that a flow velocity and a flow rate are naturally reduced. In this case, the orifice 100 according to the present invention may obtain hydraulic performance similar to that of a multi-stage orifice according to the related art, that is, a multi-stage orifice manufactured by connecting several orifices having circular holes to each other in series only by forming the pressed portion 120 in which the slit 121 is formed (This will be described in more detail in a paragraph ‘[3] Confirmation of Performance of Orifice According to the Present Invention’).
As such, in the method of manufacturing an orifice according to the present invention, the orifice effectively realizing a desired hydraulic performance may be very easily and smoothly manufactured through a simple manufacturing of forming a channel region having a cross section close to a rectangular shape by pressing a part of the capillary pipe. It has been described above that the orifice according to the related art used in order to spray the very small amount of fluid in the ultra-high pressure in the oxidant recirculation process of the launch vehicle needs to use the multi-stage structure in order to obtain the desired hydraulic performance. Conventionally, in a process of manufacturing such a multi-stage orifice, processes such as an assembling process, an aligning process, and the like, have been required, and there was a problem such as an excessive increase in a volume and a mass. However, in the present invention, the orifice is formed of a single component, and a volume and a mass of the orifice may thus be reduced as compared with the multi-stage orifice according to the related art. Therefore, miniaturization and lightness of the orifice may be easily realized. Furthermore, since the orifice is formed of the single component, processes such as an assembling process, an aligning process, and the like, are not required at the time of manufacturing the orifice, such that the number of components and the number of processes may be minimized and economical efficiency and productivity are maximized. That is, in a case where the orifice according to the present invention is applied to a device such as a system that conventionally has to endure difficult processes and an excessive volume and mass in order to obtain the desired hydraulic performance, for example, an oxidizer recirculation system of the launch vehicle described above, all the problems occurring by applying the multi-stage orifice according to the related art may be basically solved.
Detailed construction of method of manufacturing orifice according to the present invention and derivation principle
Hereinafter, a derivation principle of the relationship equation between the flow rate and the stress in the stress value calculating step described above will be described in detail.
It may be seen from the result as described above that when the pressing force, the length of the pressed portion, or the like, is adjusted, a desired flow rate of the fluid passing through the slit in the manufactured orifice may be adjusted. On the basis of such a tendency, in the present invention, a relationship equation between a flow rate of the fluid passing through the orifice and a stress acting at the time of manufacturing the orifice was derived.
{dot over (m)}=C1exp(C2S)
(here, {dot over (m)}: Flow rate, S: Stress, C1: Positive constant, and C2: Negative constant).
In an equation based on an actual experimental value, C1 is 4.0437 and C2 is −3*10−9, but the present invention is not limited thereto. That is, specifically, values of C1 and C2 may be changed depending on an outer diameter, a thickness of a wall, a material, and the like, of the tube used to manufacture the orifice. However, in a case where the material of the tube is stainless steel, the outer diameter of the tube is 1.588 mm ( 1/16 inch), and the thickness of the wall of the tube is 0. 4 mm, the values of C1 and C2 may be used as they are.
When the relationship equation between the flow rate and the stress as described above is derived by a result graph as illustrated in
A=WL=(2t+ΠDi/2)L
(here, A: Area of pressed portion, W: Width of pressed portion, L: Length of pressed portion, t Thickness of wall of body portion, and Di: Inner diameter of body portion).
When the area of the pressed portion calculated as described above is used, the pressing force value may be easily calculated from the following relationship equation:
F=SA
(here, F: Pressing force, S: Stress, and A: Area of pressed portion).
As described above, in the present invention, the stress value required in order to obtain the desired flow rate value may be calculated and determined from the relationship equation between the flow rate and the stress having the exponential function form as illustrated in
Confirmation of Performance of Orifice According to the Present Invention
In order to test hydraulic performance of orifices of several standards manufactured as described above, test systems having forms as illustrated in
The following equations are to calculate an effective cross-sectional area in a condition in which a flow velocity of the helium gas reaches at a sound velocity, such that a speed and a mass flow rate are not increased any more, that is, a choking condition. Here, the calculation of the effective cross-sectional area means calculation of an area when a capillary pipe orifice elongated in a length direction is replaced by an orifice formed in a simple hole shape
(here, A: Effective cross-sectional area (mm2), {dot over (m)}:
Flow rate (kg/s), R: Gas constant, T: temperature (K) in Absolute pressure (MPa) in front of orifice).
When taking into consideration of such several experiment results, the following interesting tendency is found. That is, the orifices according to the present invention manufactured while changing the force pressing the tube having a predetermined length, a predetermined ratio exists between a cross-sectional area and an effective cross-sectional area.
The present invention is not limited to the abovementioned exemplary embodiments, but may be variously applied. In addition, the present invention may be variously modified by those skilled in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims.
According to the present invention, the orifice effectively realizing a desired hydraulic performance may be very easily and smoothly manufactured through a simple manufacturing method of forming a channel region having a cross section close to a rectangular shape by pressing a part of the capillary pipe. In addition, according to the present invention, geometric numerical values of an orifice to be manufactured, a force required for manufacturing the orifice, and the like, may be very easily calculated using given hydraulic conditions and a desired hydraulic performance, such that design and manufacturing easiness are maximized. Further, according to the present invention, the orifice itself may be very easily manufactured, and the orifice itself is formed of the single component, such that processes such as an assembling process, an aligning process, and the like, are not required at the time of manufacturing the orifice. Therefore, the number of components and the number of processes are minimized, such that economical efficiency and productivity are maximized. Therefore, a volume and a mass of the orifice are reduced, such that miniaturization and lightness of the orifice may be easily realized.
Particularly, according to the present invention, when the orifice according to the present invention is manufactured to have the same channel resistance as that of a general orifice, the orifice according to the present invention is formed to have a cross section much larger than that of the general orifice. Therefore, a problem occurring in a case of spraying a very small amount of fluid in ultra-high pressure and very low temperature environments, that is, a risk that the orifice will be blocked by foreign object particles or ice particles generated due to freezing of the residual gas may be significantly reduced as compared with a case of using the general orifice.
As described above, according to the present invention, the very small amount of fluid may be sprayed in the ultra-high pressure and very low temperature environments, and the orifice whose miniaturization and lightness are realized may be easily manufactured, and the orifice may thus be very smoothly applied to a severe and extreme environment such as a launch vehicle, or the like. In addition, since the orifice itself according to the present invention has a high economical efficiency and productivity, a production cost of an entire device such as the launch vehicle or the like to which such an orifice is applied may also be reduced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2019-0134999 | Oct 2019 | KR | national |
