A hot jet device and method for controlling flow-induced noise of an underwater airfoil

Abstract

The application discloses a kind of hot jet device and method for controlling underwater airfoil flow-induced noise, it relates to the field of acoustic measurement.It solves the problem of traditional flow-induced noise.The device of the present application is connected in order from the inlet pipe, the inlet ball valve, the hot jet tank, the jet ball valve from the heating tank to the outlet end direction, then connected into jet pipe, the outlet of jet pipe is connected with temperature sensor and flowmeter, the bottom of hot jet tank is connected with driving motor through steel wire rod, driving motor is connected with motor drive controller, finally water is ejected from the trailing edge area of underwater airfoil.The hot jet of the present application not only supplements the momentum of boundary layer and uses temperature to change the viscosity of water, can further stabilize flow field, effectively improve the sound stealth performance of underwater vehicle with airfoil structure.

Description

Technical Field

[0001] This invention belongs to the field of acoustic measurement, specifically relating to a thermal jet device and method for controlling the flow-induced noise of underwater airfoils. Background Technology

[0002] Currently, airfoil structures are widely used in underwater vehicles. Under the influence of viscous resistance and adverse pressure gradients, the airfoil boundary layer separates, generating numerous boundary layer separation vortices and inducing intense velocity and pressure fluctuations. These large turbulent fluctuations not only generate flow noise but also excite the shell structure to produce high levels of flow-induced noise, posing significant challenges to the acoustic stealth performance of underwater vehicles and the overall detection performance of sonar systems. Compared to passive flow control technologies, which cannot adapt to the complex and ever-changing marine environment, active flow control technologies offer greater controllability and are more suitable for flow-induced noise control.

[0003] Underwater jets can inject momentum into the airfoil boundary layer, resisting boundary layer flow separation and reducing the scale of boundary layer separation vortices. However, conventional jet sources use pump-driven excitation, which, while achieving ideal jet velocities, introduces additional noise due to the periodic pulsation excitation, severely impacting control performance and making them unsuitable for underwater flow-induced noise control. Some jet devices utilize gravity drive, eliminating line spectrum noise from the drive unit, but these devices require specific height differences, and the jet velocity cannot be kept stable, limiting their practical application in engineering. Therefore, it is necessary to explore jet devices suitable for engineering applications. The viscosity of water is highly correlated with temperature; for every degree Celsius increase in temperature, the viscosity decreases by approximately 2%. Underwater thermal jets can raise the water temperature near the wall, significantly reducing the water viscosity and consequently decreasing wall shear stress. Under the temperature effect of the thermal jet, the sudden initiation of turbulent vortices decreases, and pressure pulsations in the flow field become less intense. Therefore, underwater thermal jets not only inject momentum into the boundary layer but also, through their temperature effect, further stabilize the flow field, potentially leading to better control performance. Summary of the Invention

[0004] This invention addresses the problem of high flow-induced noise generated by boundary layer flow separation in underwater airfoils by proposing a thermal jet device and method for controlling such noise. Facing challenges such as the additional pulsation and noise generated when the underwater jet is driven by a pump, and the instability of jet velocity and high engineering difficulty when driven by gravity, this invention provides a thermal jet device and method for controlling flow-induced noise in underwater airfoils. The technical solution adopted to solve the above problems is as follows:

[0005] This invention discloses a thermal jet device for controlling the flow-induced noise of underwater airfoils, comprising a first heating tank, a second heating tank, a water inlet to the first heating tank, a water inlet to the second heating tank, a first heating element, a second heating element, a first inlet pipe, a second inlet pipe, a first inlet ball valve, a second inlet ball valve, a first thermal jet tank, a second thermal jet tank, a first jet ball valve, a second jet ball valve, a first lead screw, a second lead screw, a drive motor, a motor drive controller, a jet pipe, a flow meter, a temperature sensor, a piston, and an insulation layer. The first heating tank is connected to the first thermal jet tank via the first inlet pipe and the first inlet ball valve. The first and second hot jet tanks are connected to each other via a second inlet pipe and a second inlet ball valve. The first and second hot jet tanks are connected to the jet pipe via a first jet ball valve and a second jet ball valve, respectively. A flow meter and a temperature sensor are installed at the top of the jet pipe. The first and second heating elements are installed in the first and second hot jet tanks, respectively. The output end of the drive motor is connected to the first and second lead screws. The drive motor is connected to the motor drive controller. The piston is connected above the first and second lead screws. The outer walls of the first and second hot jet tanks are provided with a heat insulation layer.

[0006] A method for controlling the flow-induced noise of a thermal jet in an underwater airfoil, comprising the following steps:

[0007] Step 1: Fill the first heating tank and the second heating tank with water, connect the first heating element and the second heating element to the power supply, and heat the water in the first heating tank and the second heating tank to 65-75 degrees Celsius.

[0008] Step 2: Close the first and second jet ball valves, open the first and second inlet ball valves, and start the motor drive controller to control the drive motor to draw hot water into the first and second hot jet tanks by piston. When the hot water in the first and second hot jet tanks reaches the spraying requirements, close the first, second, and second inlet ball valves and open the first jet ball valve. The drive motor will step forward to inject the hot water in the first hot jet tank into the jet pipe and out from the tail of the underwater airfoil. At the same time, the flow meter reads the corresponding hot jet velocity and the temperature sensor reads the corresponding hot jet temperature.

[0009] Step 3: When the hot water in the first hot jet tank is insufficient to meet the jetting requirements, close the first jet ball valve and open the first inlet ball valve to replenish the first hot jet tank with hot water. At this time, open the second jet ball valve and use the second hot jet tank as the hot jet source. Drive the motor to step forward and inject the hot water in the second hot jet tank into the jet pipe and out from the tail of the underwater airfoil. At the same time, the flow meter reads the corresponding hot jet velocity and the temperature sensor reads the corresponding hot jet temperature. Repeat the above steps to achieve uninterrupted hot jet to control the flow-induced noise of the underwater airfoil.

[0010] The beneficial effects of the thermal jet device and method for controlling the flow-induced noise of underwater airfoils according to the present invention are as follows: First, underwater jet sources are generally driven by pump sources. During the rotation of the blades in the pump, pulsating forces and noise are generated at the corresponding frequencies of shaft frequency and blade frequency, which seriously affects the control effect of the flow-induced noise of underwater airfoils. The jet velocity driven by gravity cannot be kept constant and requires a certain height difference to achieve, which is not very practical for engineering. The thermal jet device in this invention achieves underwater thermal jetting by driving a stainless steel screw at a constant speed using a drive motor. This avoids adding additional power sources and noise interference while ensuring the stability of the jet velocity, and is expected to have better control effects. Secondly, compared with ordinary underwater jets, this invention heats the water before jetting, which raises the water temperature in the tail region of the underwater airfoil. This not only utilizes the momentum effect of the jet to replenish the kinetic energy of the flow separation zone at the tail of the airfoil, delaying the occurrence of flow separation and reducing the degree of flow separation, but also takes advantage of the characteristic that the higher the water temperature, the lower the viscosity coefficient, further reducing the wall shear stress and the pulsation characteristics of the flow field, making the flow field more stable. Waste heat from ships, such as engine cooling water, can be used to provide the hot jet water source for the device. This not only further reduces flow-induced noise but also allows for the reuse of waste heat. Secondly, two sets of hot jet supply devices are arranged, and the supply source is controlled by ball valves. If the water supply in one hot jet tank is insufficient, the other hot jet tank can be used to supply water, and water can be replenished to the other hot jet tank during this period. This design ensures a stable and uninterrupted supply of hot jet water. The underwater hot jet device is driven by a screw-connected motor, resulting in a stable jet velocity without generating additional pulsation or noise interference. The ejected hot jet not only replenishes momentum to the boundary layer but also uses temperature to change the viscosity of the water, further stabilizing the flow field and effectively improving the acoustic stealth performance of underwater vehicles with airfoil structures. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the device of the present invention. Figure 2 yes Figure 1 Cross-sectional schematic diagram of the intermediate-heat jet tank. Figure 3 yes Figure 1 Cross-sectional schematic diagram of the heating tank. Figure 4 This is a flowchart of a thermal jet method for controlling flow-induced noise in underwater airfoils according to the present invention. 16 in the figure represents the tail section of the underwater airfoil. Detailed Implementation

[0012] Specific implementation method one: Combining Figures 1 to 3This embodiment describes an implementation. This embodiment comprises a first heating tank 1-1, a second heating tank 1-2, a first heating tank inlet 2-1, a second heating tank inlet 2-2, a first heating element 3-1, a second heating element 3-2, a first inlet pipe 4-1, a second inlet pipe 4-2, a first inlet ball valve 5-1, a second inlet ball valve 5-2, a first hot jet tank 6-1, a second hot jet tank 6-2, a first jet ball valve 7-1, a second jet ball valve 7-2, a first lead screw 8-1, a second lead screw 8-2, a drive motor 9, a motor drive controller 10, a jet pipe 11, a flow meter 12, a temperature sensor 13, a piston 14, and an insulation layer 15. The first heating tank 1-1 is connected to the first hot jet tank 6-1 via the first inlet pipe 4-1 and the first inlet ball valve 5-1. The second heating tank... The hot tank 1-2 is connected to the second hot jet tank 6-2 through the second inlet pipe 4-2 and the second inlet ball valve 5-2. The first hot jet tank 6-1 and the second hot jet tank 6-2 are connected to the jet pipe 11 through the first jet ball valve 7-1 and the second jet ball valve 7-2, respectively. The upper part of the jet pipe 11 is equipped with a flow meter 12 and a temperature sensor 13. The first heating element 3-1 and the second heating element 3-2 are respectively installed in the first heating tank 1-1 and the second heating tank 1-2. The output end of the drive motor 9 is connected to the first lead screw 8-1 and the second lead screw 8-2. The drive motor 9 is connected to the motor drive controller 10. The piston 14 is connected above the first lead screw 8-1 and the second lead screw 8-2. The tank walls of the first heating tank 1-1 and the second heating tank 1-2 are equipped with a heat insulation layer 15.

[0013] Specific Implementation Method Two: Combining Figure 1 This embodiment describes a first heating tank 1-1 and a second heating tank 1-2 made of stainless steel. Threaded openings are provided on the right and left sides of the tank bodies. The tanks have low thermal conductivity.

[0014] Specific implementation method three: Combining Figure 1 This embodiment describes the first inlet pipe 4-1 and the second inlet pipe 4-2 as described in this embodiment. They are stainless steel corrugated pipes with a diameter of 50 mm and a length of 5 m. The input ends of the first inlet pipe 4-1 and the second inlet pipe 4-2 are high-pressure quick-connect interfaces connected to the first heating tank 1-1 and the second heating tank 1-2. The output ends of the first inlet pipe 4-1 and the second inlet pipe 4-2 are connected to the first inlet ball valve 5-1 and the second inlet ball valve 5-2 via threads.

[0015] Specific implementation method four: Combination Figure 1 This embodiment is described. The first step described in this embodiment...

[0016] The flow ball valve 5-1 and the second inlet ball valve 5-2 are made of brass and have a size of DN50. The first jet ball valve 7-1 and the second jet ball valve 7-2 are also copper ball valves and have a size of DN40.

[0017] Specific Implementation Method Five: Combining Figure 1 , Figure 2 This embodiment describes the piston 14, which is an aluminum alloy piston equipped with a high-temperature resistant sealing ring. The lower end of the piston 14 is threadedly connected to the upper end of the first lead screw 8-1 and the second lead screw 8-2.

[0018] Specific Implementation Method Six: Combination Figure 1 This embodiment describes a drive motor 9, which is a linear high-thrust stepper motor.

[0019] Specific implementation method seven: Combination Figure 1 This embodiment describes the flow meter 12. The flow meter 12 described in this embodiment is an electromagnetic flow meter, model DN40 with PTFE lining. Both ends are fastened to the jet pipe by flanges and bolts, and the middle is sealed with a rubber gasket.

[0020] Specific implementation method eight: Combination Figure 1 This embodiment is described below. The temperature sensor 13 described in this embodiment is a thermocouple-type temperature sensor.

[0021] Specific Implementation Method Nine: Combining Figure 1 This embodiment describes the use of insulating cotton for the insulation layer 15. This ensures a stable water temperature inside the tank.

[0022] Specific Implementation Method Ten: Combining Figure 4 This embodiment describes the steps of a thermal jet method for controlling flow-induced noise in underwater airfoils according to this embodiment:

[0023] Step 1: Fill the first heating tank 1-1 and the second heating tank 1-2 with water, connect the first heating element 3-1 and the second heating element 3-2 to the power supply, and heat the water in the first heating tank 1-1 and the second heating tank 1-2 to 65-75 degrees Celsius.

[0024] Step 2: Close the first jet ball valve 7-1 and the second jet ball valve 7-2, open the first inlet ball valve 5-1 and the second inlet ball valve 5-2, start the motor drive controller 10 to control the drive motor 9 to draw hot water into the first hot jet tank 6-1 and the second hot jet tank 6-2 by the piston 14. When the hot water in the first hot jet tank 6-1 and the second hot jet tank 6-2 reaches the spraying requirement, close the first inlet ball valve 5-1, the second inlet ball valve 5-2 and the second jet ball valve 7-2, open the first jet ball valve 7-1, and drive the motor 9 to step forward, injecting the hot water in the first hot jet tank 6-1 into the jet pipe 11 and out from the underwater airfoil tail. At the same time, the flow meter 12 reads the corresponding hot jet velocity and the temperature sensor 13 reads the corresponding hot jet temperature.

[0025] Step 3: When the hot water in the first hot jet tank 6-1 is insufficient to meet the jetting requirements, close the first jet ball valve 7-1 and open the first inlet ball valve 5-1 to replenish the first hot jet tank 6-1 with hot water. At this time, open the second jet ball valve 7-2 and use the second hot jet tank 6-2 as the hot jet source. Drive the motor 9 to step forward and inject the hot water in the second hot jet tank 6-2 into the jet pipe 11 and out from the tail of the underwater airfoil. At the same time, the flow meter 12 reads the corresponding hot jet velocity and the temperature sensor 13 reads the corresponding hot jet temperature. Repeat the above steps to achieve uninterrupted hot jet to control the flow noise of the underwater airfoil.

[0026] The thermal jet device for controlling the flow-induced noise of underwater airfoils of the present invention achieves thermal jetting by driving motor 9, without generating additional pulsating force and noise. The entire device can achieve uninterrupted thermal jetting by switching the first inlet ball valve 5-1, the first jet ball valve 7-1, the second inlet ball valve 5-2, and the second jet ball valve 7-2. It not only replenishes the kinetic energy of the airfoil boundary layer with jetting, but also increases the temperature near the wall, thereby reducing the pulsation of the flow field and achieving better flow-induced noise control effect.

[0027] The mechanism by which underwater hot jets control flow-induced noise exists in two aspects: First, the underwater hot jet is ejected from the trailing edge of the underwater airfoil, adding momentum to the trailing edge. Under the influence of fluid viscosity and adverse pressure gradient, the kinetic energy of the boundary layer in the trailing edge region is continuously consumed, eventually leading to flow reversal and boundary layer separation. At the point of flow separation, the vertical gradient of the flow velocity in the boundary layer is zero. The kinetic energy injected by the underwater hot jet shifts the flow separation point backward and significantly reduces the size of the flow separation vortex, thus reducing the flow-induced noise of the underwater airfoil. Second, the viscosity coefficient of water decreases with increasing temperature. This decrease in viscosity not only reduces the water's resistance to viscosity, delaying the occurrence of boundary layer separation, but also reduces the sudden initiation of turbulent vortices, further stabilizing the flow field. Therefore, the temperature effect of the hot jet further enhances the control effect of flow-induced noise in the underwater airfoil.

[0028] Working principle of the device:

[0029] Water is first injected into the first heating tank 1-1 through the inlet 2-1. After being heated by the first heating element 3-1, the water enters the first inlet pipe 4-1 and the first inlet ball valve 5-1, and then enters the first hot jet tank 6-1. Under the action of the drive motor 9 driving the first lead screw 8-1 and the piston 14, the hot water is injected into the jet pipe 11, passes through the flow meter 12 and the temperature sensor 13, and then exits from the trailing edge of the underwater airfoil. When the hot water in the first hot jet tank 6-1 is insufficient, the hot water in the second heating tank 1-2 is heated by the second heating element 3-2, flows through the second inlet pipe 4-2 and the second inlet ball valve 5-2, and then enters the second hot jet tank 6-2. Under the action of the drive motor 9 driving the second lead screw 8-2 and the piston 14, the hot water is injected into the jet pipe 11, passes through the flow meter 12 and the temperature sensor 13, and then exits from the trailing edge of the underwater airfoil. The above process is carried out alternately to achieve uninterrupted hot jet.

[0030] The above embodiments are merely exemplary and do not limit the present invention. It should be noted that those skilled in the art should be aware of these limitations.

[0031] For those skilled in the art, any other equivalent changes, modifications, substitutions, and variations made under the guidance of the technical solutions provided by this invention should be considered within the scope of protection of this invention.

Claims

1. A thermal jet device for controlling the flow-induced noise of underwater airfoils, comprising a first heating tank, a second heating tank, a water inlet to the first heating tank, a water inlet to the second heating tank, a first heating element, a second heating element, a first inlet pipe, a second inlet pipe, a first inlet ball valve, a second inlet ball valve, a first thermal jet tank, a second thermal jet tank, a first jet ball valve, a second jet ball valve, a first lead screw, a second lead screw, a drive motor, a motor drive controller, a jet pipe, a flow meter, a temperature sensor, a piston, and an insulation layer, characterized in that: The first heating tank is connected to the first hot jet tank via a first inlet pipe and a first inlet ball valve. The second heating tank is connected to the second hot jet tank via a second inlet pipe and a second inlet ball valve. The first and second hot jet tanks are connected to the jet pipe via a first jet ball valve and a second jet ball valve, respectively. A flow meter and a temperature sensor are provided at the top of the jet pipe. The first and second heating elements are respectively installed inside the first and second heating tanks. The output end of the drive motor is connected to the first and second lead screws. The drive motor is connected to the motor drive controller. The piston is connected above the first and second lead screws. The tank walls of the first and second heating tanks are provided with a heat insulation layer. The control drive motor uses a piston to draw hot water into the first and second hot jet tanks; Driven by the motor, the first lead screw and piston inject hot water into the jet pipe, which then passes through the flow meter and temperature sensor before exiting from the trailing edge of the underwater airfoil. Driven by the motor, the second lead screw and piston inject hot water into the jet pipe, which then passes through the flow meter and temperature sensor before exiting from the trailing edge of the underwater airfoil. This process is repeated to achieve a continuous hot jet.

2. The thermal jet device for controlling underwater airfoil flow-induced noise according to claim 1, characterized in that: The first and second heating tanks are made of stainless steel, and threaded openings are provided on the right and left sides of the tank bodies.

3. The thermal jet device for controlling underwater airfoil flow-induced noise according to claim 1, characterized in that: The first and second inlet pipes are stainless steel corrugated pipes with a diameter of 50mm and a length of 5m. The input ends of the first and second inlet pipes are high-pressure quick-connect interfaces that connect to the first and second heating tanks. The output ends of the first and second inlet pipes are connected to the first and second inlet ball valves via threads.

4. The thermal jet device for controlling underwater airfoil flow-induced noise according to claim 1, wherein... The features are as follows: the first inlet ball valve and the second inlet ball valve are made of brass and have a size of DN50; the first jet ball valve and the second jet ball valve are also made of copper and have a size of DN40.

5. A thermal jet device for controlling underwater airfoil flow-induced noise according to claim 1, characterized in that: The piston is made of aluminum alloy and equipped with a high-temperature resistant sealing ring. The lower end of the piston is threadedly connected to the upper end of the first lead screw and the second lead screw.

6. A thermal jet device for controlling underwater airfoil flow-induced noise according to claim 1, characterized in that: The drive motor is a linear high-thrust stepper motor.

7. A thermal jet device for controlling underwater airfoil flow-induced noise according to claim 1, characterized in that: The flow meter is an electromagnetic flow meter, model DN40 with PTFE lining. Both ends are fastened to the jet pipe by flanges and bolts, and the middle is sealed with a rubber gasket.

8. A thermal jet device for controlling underwater airfoil flow-induced noise according to claim 1, characterized in that: The temperature sensor described is a thermocouple-type temperature sensor.

9. A thermal jet device for controlling underwater airfoil flow-induced noise according to claim 1, characterized in that: The insulation layer is made of insulation cotton.

10. A method for controlling underwater airfoil flow-induced noise using any one of the thermal jet devices according to claims 1 to 9, characterized in that: The steps of this method are as follows: Step 1: Fill the first heating tank and the second heating tank with water, connect the first heating element and the second heating element to the power supply, and heat the water in the first heating tank and the second heating tank to 65-75 degrees Celsius. Step 2: Close the first and second jet ball valves, open the first and second inlet ball valves, and start the motor drive controller to control the drive motor to draw hot water into the first and second hot jet tanks by piston. When the hot water in the first and second hot jet tanks reaches the spraying requirements, close the first, second, and second inlet ball valves and open the first jet ball valve. The drive motor will step forward to inject the hot water in the first hot jet tank into the jet pipe and out from the tail of the underwater airfoil. At the same time, the flow meter reads the corresponding hot jet velocity and the temperature sensor reads the corresponding hot jet temperature. Step 3: When the hot water in the first hot jet tank is insufficient to meet the jetting requirements, close the first jet ball valve and open the first inlet ball valve to replenish the first hot jet tank with hot water. At this time, open the second jet ball valve and use the second hot jet tank as the hot jet source. Drive the motor to step forward and inject the hot water in the second hot jet tank into the jet pipe and out from the tail of the underwater airfoil. At the same time, the flow meter reads the corresponding hot jet velocity and the temperature sensor reads the corresponding hot jet temperature. Repeat the above steps to achieve uninterrupted hot jet to control the flow-induced noise of the underwater airfoil.

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