RU235034U1 - Device for tracer visualization of flows in a hydrodynamic pipe using the hydrogen bubble method - Google Patents

Abstract

A device for tracer visualization of flows in a hydrodynamic pipe is proposed. The device is one of two electrodes participating in the electrolysis process. The device is a rectangular frame installed in front of the working part of the hydrodynamic pipe, inside which metal wire strings are stretched horizontally and vertically, perpendicular to each other, each of which is made with the possibility of connecting to a visualization plane switching control mechanism, which is an electronic control unit, while the strings are located so that they do not touch each other, and the inner surface of the frame is made flush with the mating parts of the inner surface of the walls of the hydrodynamic pipe.

Description

The utility model relates to the field of hydrodynamics and is intended for use in hydrodynamic pipes in experimental studies of the processes of flow around objects of various geometric shapes, including for solving applied problems related to the optimization of the shape of aircraft, land and underwater vehicles in order to improve their operational characteristics, as well as when performing laboratory work during full-time or distance learning of the basics of experimental hydrodynamics in courses of additional professional education.

There are several ways to visualize flows in hydrodynamic pipes (HDP): 1) introducing streams of colored liquid from a special comb into the flow; 2) introducing solid microparticles into the flow.

Both of these methods are not very suitable for use in closed-loop gas turbines, as they contaminate the circulating fluid, which leads to the need for its frequent replacement or filtration.

Another method of tracer visualization of flows is the method of visualization using hydrogen bubbles (HB), which are formed during the electrolysis of water on the cathode. One electrode (cathode) is installed in front of the working part (WF), the second electrode (anode) is installed behind the WF. When the electrodes are connected to a DC source, the electrolysis process is started and a veil of hydrogen bubbles comes off the cathode, caught by the liquid flow.

With an ideal laminar flow in the RF, this veil looks like a flat sheet, but when flowing around the object (model) under study, the current lines are distorted, and the flow pattern changes accordingly, which is clearly visualized using this technology.

The bubble generators published in Hydrogen Bubble Visualization Chapter January 2012 (https://www.researchgate.net/publication/303784988 Access date: 01.11.2024) are taken as an analogue. These generators are a structure consisting of two elements: a U-shaped holder and an electrode fixed to it, on which bubbles are generated and, picked up by the flow, form a bubble plane. Depending on how it is supposed to position the electrode - in a vertical or horizontal plane, their design is slightly different. The disadvantage of such generators is that the holders, being in the flow, strongly disturb it, and to change the coordinate of the bubble generation plane, it is necessary to manually rearrange the holder or replace it.

The objective of this utility model is to create a device for tracer visualization of flows in a hydrodynamic pipe using the hydrogen bubble method, in which the coordinate of the bubble generation plane is changed by the operator from his automated workstation in automatic mode, and the design of the holder eliminates flow disturbance.

The technical result of the present utility model is a significant reduction in the time for changing the coordinate of the bubble generation plane and the uniqueness of its positioning both during one launch and from launch to launch.

The technical result is achieved by the features of a device for tracer visualization of flows in a hydrodynamic pipe, which is one of two electrodes participating in the electrolysis process. The device is a rectangular frame installed in front of the working part of the hydrodynamic pipe, inside which metal wire strings are stretched horizontally and vertically, perpendicular to each other, each of which is made with the possibility of connecting to a control mechanism for switching the coordinate of the visualization planes, which is an electronic control unit, while the strings are stretched so that they do not touch each other, and the inner surface of the frame is made flush with the mating parts of the inner surface of the walls of the hydrodynamic pipe.

The proposed device is illustrated by the following figures:

Fig. 1 – diagram of a device for tracer visualization of flows in a hydrodynamic pipe;

Fig. 2 – diagram of the working part of the hydrodynamic pipe.

The device is a rectangular frame (Fig. 1) installed in front of the working part of the hydrodynamic tube (Fig. 2, pos. 7), inside which, horizontally (Fig. 1, pos. 4) and vertically (Fig. 1, pos. 3), perpendicular to each other, strings made of metal wire are stretched, each of which is designed with the possibility of electrical connection by means of a cable (Fig. 1, pos. 5) to an electronic control unit (not shown in the figures) by switching the coordinates of the visualization plane, while the strings are stretched so that they do not touch each other. Thus, each string, connected at the moment, acts as an electrode from which a veil of bubbles comes off, which sets the coordinate of the visualization plane. And the inner surface of the frame (Fig. 1, pos. 2) is made flush with the mating parts of the inner surface of the walls of the hydrodynamic tube (Fig. 2, pos. 6). Such a design allows remote control of the coordinate of the PV source. The generated PV (Fig. 2, pos. 8), captured by the flow, in their entirety look like a flat sheet, oriented in a horizontal or vertical plane, depending on which of the electrodes (string) of the cathode is connected.

Considering that the PV have positive buoyancy, to obtain a reliable picture of the flow around the object under study, it is necessary to minimize the value of the vertical displacement of the PV. The speed of the rise of gas bubbles is affected by the size of the bubbles themselves and the presence of organized circulation of the electrolyte.

The size of the PV depends on the surface tension of the material from which the electrode is made and its geometric shape. The surface tension in turn depends on the electrode potential. If the electrode is made of a thin wire with a diameter of D _n , then the diameter of the PV will be (0.2÷0.5) D _n .

If the choice of material is made based on the above criteria, then the best material for cathode electrodes is platinum (Pt) wire with a diameter of D_n≤ 50 microns, but this does not exclude the possibility of using wire made of another metal. Platinum is a fairly expensive material and it is not always advisable to choose it.

The potential value on the electrode and the current are selected during the equipment setup process depending on the technical task at hand.

Final adjustment can also be done by moving the model vertically to the desired position relative to the horizontal rendering plane.

To control the change of coordinates of the formed bubble planes, including from horizontal to vertical and back, a mechanism is used, which is an electronic unit containing a controller with a module of electronic keys, the number of which corresponds to the number of electrodes on the electrode frame.

The device (Fig. 1) is installed on the horizontal section of the gas turbine engine before the RF (Fig. 2, pos. 7). The second electrode (anode) is located beyond the RF boundary (Fig. 2, pos. 9), and oxygen bubbles _O2 (Fig. 2, pos. 10) are generated on it, which are also picked up by the flow and carried beyond the RF boundary. The model under study (Fig. 2, pos. 11), fixed on the holder (Fig. 2, pos. 12), is located in the geometric center of the RF, in the core of the flow, with the possibility of vertical movement.

The operator, in accordance with the test program, selects a section using the control mechanism, in the plane of which the flow pattern around the object under study is recorded using photo and video equipment. This eliminates the need for manual rearrangement of the frame with a single electrode, which leads to a significant reduction in the time for changing the coordinate of the bubble generation plane and ensures the uniqueness of its positioning both during one start and from start to start.

The inner surface of the cathode electrode frame in the working position, i.e. after its installation in a special socket in front of the RF, forms a single surface with the inner surface of the working path of the gas turbine engine, thereby eliminating the turbulent effect on the flow.

Claims (1)

A device for tracer visualization of flows in a hydrodynamic pipe, which is one of two electrodes participating in the electrolysis process, characterized in that it is a rectangular frame installed in front of the working part of the hydrodynamic pipe, inside which metal wire strings are stretched horizontally and vertically, perpendicular to each other, each of which is designed with the possibility of connecting to a visualization plane switching control mechanism, which is an electronic control unit, while the strings are located so that they do not touch each other, and the inner surface of the frame is made flush with the mating parts of the inner surface of the walls of the hydrodynamic pipe.