Hydrodynamic cavitation optical detector

Description

5 Optical hydrodynamic cavitation detector Field of invention

[001] The present invention relates to a hydrodynamic cavitation plume detector from fluid flow in a convergent-divergent tube and an orifice plate with predefined flow rate and pressure. An optical sensor, positioned at a specific point in the pipe, opposite a light source, is responsible for reading the interference of the cavitation plume formed, and subsequently identifying the intensity of the hydrodynamic cavitation produced. The support and light isolation of the transparent structure is achieved by a dark chamber developed in polymeric material with the dimensions of the cavitation device, being coupled to the tube by screws and nuts, containing specific openings for the installation of the light source and optical sensor. Fundamentals of the invention

[002] Hydrodynamic cavitation is a phenomenon formed from the formation and implosion of bubbles and microbubbles present in a liquid. The intensity of this phenomenon can be assessed by the number of bubbles formed, which cause the well-known cavitation plume. This phenomenon must be monitored to ensure the proper application of cavitation. For monitoring, the method of light scattering through the fluid can be used, which is applicable for identifying and quantifying the phenomenon.

[003] The efficiency of the hydrodynamic cavitation process is entirely dependent on the size and quantity of microbubbles formed, as well as their ability to collapse in a short period. Therefore, there is a search for devices and systems that amplify the cavitation plume, to increase the system's treatment capacity. For plume monitoring, an optical sensor is needed that can identify the different phases of the liquid / gas flow. Petition 870250017624, dated 06 / 03 / 2025, page 13 / 31 / 5

[004] In a system where there is a transparent pipe in the region where cavitation occurs, it is possible to position a light source on one side of the pipe, and on the diametrically opposite side position an optical sensor such as a photodiode, for example. This sensor, with its proper signal conditioning, is able to measure the intensity of the light transmitted as it passes through the pipe filled with cavitation bubbles. The bubbles in this medium will act as heterogeneities that will cause the light to spread along a distinct optical path depending on the intensity of the cavitation. Therefore, the sensor will capture a distinct light intensity for each cavitation configuration, thus generating a relationship between light intensity and cavitation intensity.

[005] When light propagates, it is possible that it may encounter particles and other objects along its path that can cause the phenomenon of light scattering. In general terms, this phenomenon consists of the change in the trajectory of light when encountering this type of obstacle. In multiphase flows, inside transparent pipes, the presence of air and water, and the bubbles formed in the region where cavitation occurs, is visible. In particular, if a light source directed at this location is switched on, the light will undergo scattering. Upon scattering, the intensity of the light transmitted in this multiphase medium where cavitation occurs is altered, and perceptible by an optical sensor. Therefore, by inserting a light source and a light sensor in a cross-section of a hydrodynamic cavitation system, with a transparent pipe, it is possible to relate the intensity of the light measured by the optical sensor to the amount of bubbles formed at that point, as well as the intensity of cavitation present in the medium.

[006] When using a system capable of measuring light intensity, it is necessary to know about any possible light noise present, or that the environment is only illuminated by a specific, controlled, and known source. To prevent interference from other sources, a black protective cover that acts as a dark chamber is used to isolate the area where the measurement will be taken. This cover, with a specific design manufactured from a 3D-printed polymeric material, is essential for the system to produce reliable results. Brief description of the drawings Petition 870250017624, dated 06 / 03 / 2025, page 14 / 31 / 5

[007] Figure 1 represents the cross-section of the support for the cavitation detection system, constructed of polymeric material, it has an inlet for an LED flashlight (1) and an inlet for the light sensor (8), a chamber for inserting the sensor and the flashlight (9) and a screw for fixing the equipment (3) as well as an inlet for inserting a nut (2). The dark chamber (4) has two sides and six points (7) for inserting six screws (5) and six nuts (6) for fixing and light isolation of the acrylic tube.

[008] Figure 2 shows a view of the left side of the apparatus representing the inlet for an LED flashlight (1), a chamber for housing the flashlight (9) and a screw for fixing the equipment (3) together with a passage for inserting a nut (2). The dark chamber (4) has six points (7) for inserting six screws (5) and six nuts (6), four on the top and two on the bottom of the chamber, for fixing and light isolation of the acrylic tube.

[009] Figure 3 shows the top view of the apparatus, composed of the space (3) for inserting the support screw for the light sensor and LED flashlight, the dark chamber that surrounds the entire transparent tubing (4). The set of supports (7), screws (5) and nuts (6) for closing and sealing the dark chamber, showing the four connection points. It is possible to observe in the figure the support chambers for the LED flashlight and the light sensor (9), and finally, the spaces (10) intended for the installation of pressure gauges and transducers directly on the transparent tubing (11).

[0010] Figure 4 shows the collected flow rate and light intensity data in the pipe. Note that as the flow rate increases, there is greater bubble formation, which scatters the light and causes the sensor to show a decreased light intensity compared to lower flow rates. With this device it is also possible to obtain the maximum and minimum cavitation points at varying flow rates.

[0011] In addition to the variation in light intensity in relation to flow rate, the variation in pressure in the pipe and its relationship with light intensity were also observed, as shown in Figure 5. It can be seen that as the pressure decreases, the light intensity also decreases. It is also possible to observe points where there is no pressure. Petition 870250017624, dated 06 / 03 / 2025, page 15 / 31 / 5 sufficient for the formation of hydrodynamic cavitation, at points close to vapor pressure, i.e., close to -2.0 mca.

[0012] Tests were carried out with different wavelengths to determine if hydrodynamic cavitation was more sensitive to a particular wavelength in the visible spectrum. The results showed that there was no relationship between the different wavelengths and light intensity, as shown in Figure 6. Description of the invention

[0013] White light source in cylindrical shape, consisting of an LED lamp coupled to a power source;

[0014] Optical sensor consisting of a cylindrical silicon photodiode coupled to a computer for data acquisition;

[0015] Right side of the dark chamber, black in color, semicircular in shape, with four supports for cylindrical head screws with nuts on the upper edge and two on the lower edge, spaced at the same distance from each other for fixing to the transparent tubing. Three semicircles on the upper part for fitting pressure measuring instruments. Opening with support, in square shape, for installing the light source with a hexagonal screw and a nut for fixing.

[0016] Left side of the dark chamber, black in color, semicircular in shape, with four supports for cylindrical head screws with nuts on the upper edge and two on the lower edge, spaced at the same distance from each other for fixing to the transparent tubing. Three semicircles on the upper part for fitting pressure measuring instruments. Opening with support, in square shape, for insertion of the optical sensor and a hexagonal screw with nut for fixing. Examples of embodiments of the invention

[0017] In experiments conducted, hydrodynamic cavitation occurred at flow rates between 18.3 and 50.0 L / min. This result contributes to the application in low-flow systems, known as decentralized systems. The presentation of these results does not preclude application at higher flow rates, which can be tested and improved over time. Petition 870250017624, dated 06 / 03 / 2025, page 16 / 31 / 5

[0018] In the experiments performed, the system showed a pressure difference upstream-downstream of the nozzle in the range between 3.01 and 25.3 m. This range can define the model and power of the pump to be used.

[0019] Table 1 shows the pressure and pressure standard deviation data and the observed light intensity, which represent the formation of cavitation in different nozzles. For obtaining the best cavitation conditions, the triangular-shaped nozzle is the most efficient. Table 1: Data collected from the hydrodynamic cavitation system with different nozzles Parameter / Nozzle Flow Rate L / h Upstream Pressure m Downstream Pressure m Throat Pressure m Throat Pressure Standard Deviation m Luminous Intensity % Triangular 3.0 23.0 -1.066 -6.00 1.21 0.0465 Circular 2.7 23.0 -1.076 -5.92 0.75 0.0522 Pentagonal 2.8 23.0 -1.225 -5.86 1.23 0.1017 Square 2.9 23.5 -1.087 -5.70 1.05 0.0775 Hexagonal 2.85 24.3 -1.087 -5.53 1.13 0.0771

[0020] The collected data provides information on cavitation production in the system, and its detection is observed by light intensity. The detection system proves viable for application in hydrodynamic cavitation systems. Furthermore, the device is able to define cavitation intensity by detecting the number of bubbles present in the flow, as shown in Table 2. The greater the number of bubbles, the lower the light transmittance in the medium, also increasing the standard deviation of the mean. Table 2: Different flow rates and average light intensity (I) with respective standard deviation _______________________ Q [m3 / h] Average | Standard Deviation 1.2 0.7968 0.00034 1.5 0.7970 0.00501 1.8 0.7772 0.00288 2.1 0.6675 0.00873 2.3 0.5812 0.01462 2.4 0.4383 0.03183 2.6 0.2259 0.04466 2.8 0.1037 0.05525 3.0 0.0522 0.02937 Petition 870250017624, dated 06 / 03 / 2025, page 17 / 31

Claims

CLAIMS 1. Equipment for detecting hydrodynamic cavitation, characterized by an optical hydrodynamic cavitation detector, a light emitter and a receiver (photodiode) diametrically opposed and coupled in transparent tubing by supports, a dark chamber.

2. Optical method for detecting hydrodynamic cavitation, according to claim 1, characterized by a system for measuring and quantifying hydrodynamic cavitation by light intensity.

3. Equipment for detecting hydrodynamic cavitation, according to claim 1, characterized by components for light insulation of piping, comprising a dark chamber.

4. Equipment for detecting hydrodynamic cavitation, according to claim 1, characterized by coupling and support parts for the sensor and light emitter in transparent tubing. Petition 870250017624, dated 06 / 03 / 2025, page 31 / 31

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