RU2335661C1 - Method and device reducing oil injector noise - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: method consists in providing the conditions for letting the air from the oil tank air chamber into the lower-pressure mixing chamber area of the injector. The device to this effect incorporates a pipe with a throttle running from the oil tank air chamber into the lower-pressure area, one end of the pipe in the mixing chamber is directed along the flow towards the tank neck.

EFFECT: lower noise level.

2 cl, 1 dwg

Description

The invention relates to the field of pumping technology, in particular to methods and devices for reducing noise during the operation of jet pumps - oil injectors.

Known methods for reducing the noise of hydraulic devices (see, for example, Arzumanov ES "Hydraulic regulatory organs of automatic control systems", M., 1985, pp. 149-151)

- by removing the noise source at a safe distance for staff,

- by isolating the noise source by thickening the walls and coating them with sound-insulating and sound-absorbing materials,

- through the use of diffusers and silencers of various designs.

There is a method of reducing the noise of hydraulic devices by selecting the type and characteristics of the flow part of the devices, providing a decrease in flow turbulization and cavitation-free operation within the specified limits of flow and pressure changes in the medium (see ibid., Pp. 151-159).

Injectors are known in which the fluid flow supplied by the injector moves due to mixing with the flow from the nozzle having higher energy. Moreover, at the point of contact of the two flows in the mixing chamber due to intense vortex formation, regions of least pressure are formed (see, for example, the book by T. M. Basht et al. "Hydraulics, hydraulic machines and hydraulic drives", M., Mashinostroenie, 1982., pg. 230-240).

Oil injectors are known for creating excess pressure at the inlet of the main oil pump mounted on the turbine shaft, and injectors for supplying oil to the lubrication system of the unit, containing a mixing chamber with a nozzle installed in it, to which high pressure oil is supplied and into which it comes from the oil tank injected oil (see, for example, the book: V.I. Kiryukhin et al. "Steam turbines of low power KTZ", Moscow, Energomashizdat, 1987, pp. 161-162).

The present invention solves the problem of reducing the noise level produced by a working oil injector.

The technical result achieved by using the proposed method and device for its provision is to reduce the noise level produced by a working oil injector.

To achieve the specified technical result in the proposed method of reducing the noise of an operating oil injector installed on an oil tank or inside an oil tank having an oil cavity and an air cavity located above it and containing a housing with a mixing chamber that has a reduced pressure area and which is connected to the oil cavity of the oil tank, a nozzle, a neck and a diffuser with an outlet pipe create conditions for air to enter from the air cavity of the oil tank into the area with a reduced pressure injector. Moreover, in the device for reducing the noise of the working oil injector installed on the oil tank or inside the oil tank, having an oil cavity and an air cavity located above it, and comprising a housing with a mixing chamber that has a reduced pressure area and which is connected to the oil tank cavity, nozzle, neck and a diffuser with an outlet pipe, a tube with a throttle, the open end of which in the mixing chamber is directed downstream, is brought into the area with a reduced pressure of the mixing chamber from the air cavity of the oil tank side of the neck.

The drawing schematically shows an oil injector installed in an oil tank below the oil level.

To implement the proposed method of reducing the noise of an operating oil injector 1 installed in an oil tank 2, for example, a turbine (not shown), and containing a mixing chamber 3 connected by windows 4 to the oil cavity 5 of the oil tank 2, nozzle 6, neck 7 and diffuser 8 with an outlet pipe 9, the inventive device is made in the form of a tube 10, drawn from the air cavity 11 of the oil tank 2 to the reduced pressure region 12 of the mixing chamber 3 of the injector 1. At the same time, a throttle 13 is installed at the end of the tube 10 in the air cavity 11, and the other end 14 of the tube 10 is introduced n in the low pressure area 12 of the mixing chamber 3 and is directed towards the converger 15 formed in the mixing chamber 3 in front of the neck 7.

When the injector 1 is operating in the mixing chamber 3, an outer vortex layer is formed around the high-pressure oil jet emerging from the nozzle 6. The mixing region of the high-pressure oil and injected oil is generated near the outlet edge of the nozzle 6. Intensive vortex formation occurs in the mixing region, as a result of which the boundary the layer of the jet begins to entrain the slowly moving layers of the surrounding oil, pulled through the windows 4 from the oil cavity 5 of the oil tank 2. The speed of the layers of the jet is much higher than the speed growth of surrounding oil. The generated turbulent layer, which is very energetic, abruptly captures and carries away neighboring, slowly suitable layers with such a significant speed that pressure decreases to the critical along the mixing boundary - a region of reduced pressure 12 is formed - with the formation of bubbles filled with steam and gas. Moreover, stall cavitation forms on the surface of the interaction of flows with different velocities, the cause of which is free vortices and it begins not at the vaporization pressure in the oil, but significantly exceeds it, in a mechanical mixture in the form of bubbles expanding at any pressure decrease. With distance from the nozzle, the oil consumption in the jet boundary layer increases due to the involvement of the surrounding oil. The resulting caverns are carried away by the flow to the confuser 15 and then to the neck 7. The internal part of the jet is continuously thinned. In the place where the boundary layer is in contact with the walls of the confuser 15 or neck 7, the process of engagement ends. Here, the conversion of kinetic energy to static pressure begins, with the growth of which most of the caverns introduced by the flow end their existence - the bubbles cools to a microscopic size. A smaller part of them, transported by the stream, disappears in the diffuser 8. The process is accompanied by high-frequency hydraulic micromolets and high local pressure drops. “Collapse” even at very moderate hydrostatic pressure occurs very sharply and a strong rarefaction wave forms, followed by a compression wave. The developed cavitation is always accompanied by sound vibrations, perceived as cavitation noise. The formation of vapor and gas cavitation bubbles in low pressure zones at high speeds is inherent in the phenomenon of developed turbulence, which is useful in the injector, and is not a drawback of its design. The level of cavitation in the injector is determined by the pressure of the oil supplied to the nozzle, and the pressure in the mixing chamber, the amount of air dissolved in the oil. Air from the air cavity 11 with atmospheric pressure enters the reduced pressure region 12 through the throttle 13 through the pipe 10 and exits into the working stream through the hole at the end 14 of the tube 10, bent downstream towards the confuser 15, mixing with the vapor-gas bubbles, which collapse in area of the neck 7 and the diffuser 8 creates a damping effect, damping vibrations. The throttle 13 selects the amount of air flowing through the tube 10, necessary for effective damping and at the same time to maintain a healthy state of oil. From the diffuser 8 through the pipe 9, the oil of the necessary parameters is supplied to the consumer in the turbine lubrication system, etc.

Studies conducted at Nevsky Zavod OJSC showed that the sound (noise) level of lubricant injectors operating at close to design conditions reaches 100 ... 102 dBA, (for example, in the steam turbine lubrication systems of Nevsky Zavod P -16, with a capacity of 16 MW, and P-30-100 / 41-1, with a capacity of 30 MW).

Damping of oscillations during the collapse of cavitation bubbles by supplying a limited amount of air to the low pressure region of the mixing chamber using a tube with a throttle from the air cavity of the oil tank made it possible to reduce the noise level produced by these injectors to 90 dBA.

Claims (2)

1. A method of reducing the noise of a working oil injector installed on or inside an oil tank having an oil cavity and an air cavity located above it, and comprising a housing with a mixing chamber that has a reduced pressure area and which is connected to the oil tank cavity, a nozzle, a neck and a diffuser with an outlet pipe, which consists in creating conditions for air to enter from the air cavity of the oil tank into the area with a reduced pressure of the injector mixing chamber. 2. A device for reducing the noise of a working oil injector installed on an oil tank or inside an oil tank having an oil cavity and an air cavity located above it, and comprising a housing with a mixing chamber that has a reduced pressure area and which is connected to the oil tank cavity, nozzle, neck and a diffuser with an outlet pipe, characterized in that a tube with a throttle, the open end of which in the chamber of the mixture, is connected to the area with a reduced pressure of the mixing chamber sheniya is directed downstream towards the neck.