Device for creating pulsations of pressure jet

 

(57) Abstract:

The invention relates to a device for generating pulses of a jet of fluid. The invention improves the efficiency of the dynamic impact pressure liquid stream on rocks and other materials (for loosening, fracture, surface cleaning, shot peening, or other) through a communication stream pulsation mode and control the pulsation frequency in a wide range without significantly affecting the quality of the jet. Device for creating pulsations of pressure of the jet is made in the form of a wheel with blades and bracket for fixing the wheel axis to streetrider device, while the blades have an elastic connection with the wheel and the bracket also includes a brake wheel. 2 Il.

The invention relates to a device for creating pulsations jets of liquid which can be applied for effective dynamic influence on the rocks with a view to their destruction, and on other materials, including other purpose (for example, with the purpose of hardening, surface cleaning, etc.).

Known air pulsator comprising jetting comprising a barrel with a nozzle and a hollow tube for air supply (A. C. USSR N is novan on the principle of reducing water consumption, limiting performance getrootpane, and does not eliminate interference "water cushion") (on contact with destructible array) the effects of pulsations on the process of destruction.

Famous jet breaker, which is designed in the form of a rotating grating blades (Lachter Century. And. , zagaev centuries, Zaitsev, E. N. Improving the effectiveness of Gidrostroy, Hydraulic engineering, 1982, No. 7, S. 40 - 43). An intermittent stream is formed at the intersection of flowing from the nozzle stationary jet metal blades, which are mounted on the rotor driven in rotation by the electric motor.

The disadvantage of this device is the inability job pulses of high frequency, a significant deterioration in the quality of the jet, as well as explosive devices (mine).

Close to the invention of the technical solution is a device for generating pressure pulsations implemented as part of the jetting nozzle and is made in the form of a gear wheel, which is fixed on the nozzle bracket and installed on to the stream of liquid (A. C. USSR N 734421, CL. E 21 C 45/00, 15.05.80). A jet of fluid causes the wheel to rotate at the circumferential speed of the ring gear wheel close to control the interrupt frequency, not changing the fluid pressure, and causes a decrease of the dynamic characteristics of the jet due to the partial spray it when interacting with a toothed crown.

The objective of the invention is the creation of a pulsator, in order to enhance the dynamic impact of the jet on the barrier, in particular, with respect to hydrarthrosis of rocks and other materials, by reducing loss of quality of the stream and control the frequency of the pulsations.

The problem is solved as follows: for the formation of a pulsating jet uses a wheel with vanes having a resilient connection with the wheel, and the stiffness of the latter is chosen to minimize losing power jet in the interaction with her blade in a wide range of rotational speeds of the wheels, and the braking device (wheel brake) that allow you to change the speed of rotation of the chopper and to vary, thereby, the frequency of pulsation of the jet.

In Fig. 1 presents a diagram of the proposed device, side view, Fig. 2 - the same, top view. To streetrider device 1 by means of bracket 2 is attached to the axle 3, which planted the wheel 4 with the blades 5 having an elastic connection 6 with the wheel (for example the emer, screw type, to change the preload of the spring). The bracket 2 is also attached to the brake device 9 that allows you to attach to the wheel braking torque that can be implemented, for example, using the pads 10 with mechanically driven feed produced by the remote controller (not shown conventionally).

The device operates as follows.

Liquid jet from the nozzle 1, is applied to the blade 5, rejects the blade from the initial position, passing along the part of its energy to the spring 6, which reports the time of the rotation wheel 4. Upon completion of phase contact blades 5 with the jet, the elastic element 6 returns the blade to its original state, fixed restrictor 7. By increasing the angular velocity of rotation of the wheel speed of the blades in contact with the stream will be reduced (in the reference system associated with the base of the scapula), the jet will lose less of its energy when interacting with a shovel. At considerable speeds (the interrupt frequency jet 500 - 1000 Hz, with an average number of blades N < 10), to the elastic return force acting on the blade, will be added to the quasi-elastic, which will be a centrifugal force tending to set the blade in rosti jet, if the brake 9 is not powered), the interrupt frequency of the jet is determined by the number of blades N and pressure P0fluid that allows, at pressures of about 10 MPa, to produce a pulsating effect fluid barrier in kilogram frequency range. The liquid spray, and consequently, loss of quality of the jet, are minimized due to the comparative ease of displacement of the blades under the action of the jet, which is provided by appropriate selection of the stiffness of the elastic ties 6 control 8 or by installing a replacement set of these springs with different stiffness coefficient.

If you need to reduce the frequency of interruption of the jet is pressing the brake Shoe 10 to the rotating wheel surface. By adjusting the force of the clamp and thereby varying the braking torque acting on the wheel, you can set any speed breaker in the speed range from zero to the limit. A large supply of free running blades gives at any speed of rotation of the wheel mode is favorable to minimize the energy loss of the jet (reducing the liquid spray), preserving its dynamic characteristics, in comparison with a variant of the chopper blades, sestat from the surface of the wheel, eliminating the action of the braking torque, so that, in the context of an ongoing interaction between the jet and the blades, the rotation of the wheel is accelerated and, consequently, increases the frequency of pulsation of the jet passing through the interrupter.

Here is an approximate mathematical description of the motion of a wheel with blades connected by elastic links with the wheel under the action of the pressurized liquid stream.

Let us assume that the motion of the blades is in the plane component of the acute angle of < 45 with the axis of the jet. Let the speed of the liquid in the jet V0; V is the linear velocity of the rim of a wheel of radius R; N is the number of blades on the wheel; k is the stiffness coefficient of the elastic connection of the blade with the wheel; m is the mass of the blades with regard to 1/3 of the mass of the elastic element (Nesterenko, A. D., Ornatsky PP Parts and components of devices (calculation and design) - Kiev, Tekhnika, 1965 - 428): d is the path length of the blade in terms of contact with the stream (in the laboratory coordinate system).

Assuming that the blade is subjected to two forces: Fwiththe impact force (pressure) spray and Fy- force of the elastic reaction of the spring, respectively, have

Fwith- Fy= mal, (1)

where al- acceleration cat is

(2)

moreover, the time t of the location of the blades in contact with the stream is from the condition

(3)

The sign of the approximate equality is due to the fact that the blade must have a very moderate resistance to the stream and therefore the elastic connection of the blade wheel has a sufficiently low coefficient of rigidity to run

(4)

in the original stationary wheel, and xmaxd

From (4) should an estimate of the desired value of the stiffness coefficient:

(5)

which shall then be clarified by conducting experiments with a specific device.

Wheel rotation is determined by the equation:

(6)

where the elastic force relations wheels with a shovel, averaged over time (taking into account the variable nature of the action during the contact of the blades with the stream and the number of blades N); Mtthe moment of resistance of the medium (air) and the friction in the bearing of the rotation of the wheel; we write it as:

Mt= CV + fV2, (7)

where C and d are constants.

Given the linear increase of the Fywith x, we have:

(8)

where t' = d/V.

Introducing in (6) the time of tarmangani MTormartificially created for the purpose of lowering coal MTorm= PR, (9)

where P is the normal force applied to the brake pad; coefficient of friction; get final

(10)

Consider the steady-state rotation of the wheel ( = 0) for simplicity, let us assume C = 0, then from the expression (10) are for speed:

(11)

In the case P = 0 the formula (II) is simplified to mind

(12)

Note that from (II) it also follows that V = 0 when

(13)

Using (5), we can rewrite (12) as

(14)

The minimum power loss of the jet will be responsible to the value of V0requirements f corresponding to this condition, derived from (14).

Device for creating pulsations of pressure jet, comprising a wheel with blades, a bracket for fixing the wheel axis to streetrider device, wherein the blades have an elastic connection with the wheel, with the bracket mounted brake wheel.

 

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