CN105758051B - The isolated wave pipe of middle part wave arrestment chamber - Google Patents

Abstract

The invention provides an isolated gas wave tube with a middle choke cavity, which belongs to the technical fields of gas expansion refrigeration and unsteady flow gas wave transmission and energy exchange. A choke cavity with a limited volume is set in the middle of each air wave tube. Its two ends are respectively connected and connected with the front section of the air wave tube and the rear section of the air wave tube, and a flow channel that first expands and then contracts is formed inside. At the same time, the internal flow cross-sectional area of the front section of the air wave tube is smaller than the flow cross-sectional area of the rear section tube. In this way, the reflected shock wave in the tube is buffered and dissipated in the choke cavity, and the remaining part returns to the back section of the gas wave tube to enhance dissipation, so that less of it returns to the gas wave tube mouth, reducing the direct impact on the cooled gas. Heating; and reducing the temperature of the tube wall in the front section of the gas wave tube, reducing the heat transfer to the refrigerated air in the tube. The air wave tube with the new principle structure can increase the cooling efficiency by more than 5% on average, and increase the valley efficiency value when the jet frequency does not match the tube length, reduce the difficulty of design matching, and improve the variable working condition performance of air wave refrigeration.

Description

Central choke cavity isolated air wave tube

technical field

The air wave tube with the central wave-blocking cavity of the present invention is also called a receiving tube, an oscillating tube or a dissipating tube, which is mainly used in a gas wave refrigerator and belongs to the technical field of gas expansion refrigeration and unsteady flow gas wave transmission and energy exchange .

Background technique

Gas wave refrigerator is a gas expansion refrigeration machine with unique advantages, which is improved and innovated on the basis of heat separator. It is divided into two types: rotary type and static type. The significant difference between the gas wave refrigerator and the heat separator is that the former is connected with a cavity with a limited volume at the end of each of its gas wave tubes (also known as receiving tubes, oscillating tubes and dissipation tubes). , called the shock absorber (see Chinese patent ZL89213744.4).

The pulsed jet is injected from the inlet of the gas wave tube, and the trapped gas in the compressed tube generates a moving shock wave that dissipates energy and attenuates. After the attenuated motion shock wave hits the closed interface at the end of the gas wave tube, it will return to the original path, heat the pulse jet gas that has expanded and cooled at the front section of the gas wave tube and the nozzle, and increase the inlet pressure of the tube to reduce the actual jet flow. The expansion ratio reduces the cooling efficiency.

The function of the aforementioned shock wave absorbing cavity is to absorb and prevent the return of the reflected shock wave, and dissipate and disappear in the shock wave absorbing cavity. Thus, the shock absorbing cavity can improve the cooling efficiency of the air wave tube.

However, both analysis and actual measurement show that the shock absorbing cavity with a limited volume at the end of the tube can diverge, reflect and dissipate the shock wave, but because of the limited heat dissipation of the cavity wall, the effect of reducing the shock wave intensity is also limited, and the shock wave energy is not affected. After being fully attenuated, it will return to the gas wave tube after multiple reflections in the cavity and be transmitted back. The above-mentioned adverse effects still exist.

If the reflected shock wave just returns to the vicinity of the nozzle when the next pulse jet is injected into the gas wave nozzle, it will continue to propagate upstream of the gas source without affecting the refrigerated gas, and a high peak of refrigeration efficiency will appear. Otherwise, the nozzle and the refrigerated gas flowing out of the tube will be seriously heated, and efficiency troughs will appear, and the efficiency difference between the peak and the trough can be as high as 20-30%.

The characteristic that the efficiency of the gas wave refrigerator changes with the jet frequency increases the difficulty of design matching on the one hand; This results in a change in the transmission speed of the shock wave, and it arrives at the nozzle earlier or later when the jet is injected.

Even at the point where the matching efficiency is high, the reflected shock wave will increase the pressure at the nozzle, reducing the actual expansion ratio of the jet at that time, reducing the enthalpy drop, and restricting the improvement of cooling efficiency.

The fundamental way to eliminate the reflected shock wave is to fully dissipate the energy of the shock wave. Chinese patent CN200910107475.X states that the receiving tube surrounds the shell to form a cooling cavity to accelerate the absorption of the energy of the shock wave in the tube and reduce the intensity of the reflected shock wave. But it increases the structural complexity and operating conditions of the air wave machine. Moreover, the reflected shock wave can still return unimpeded to the inlet of the gas wave tube without being hindered.

Contents of the invention

The present invention provides a central wave choke cavity isolated air wave tube, also known as a central wave choke cavity isolated receiving tube, an oscillating tube or a dissipating tube, which is a brand new air wave tube structure. According to the theory of shock wave reflection and intersecting transmission, through fluid mechanics calculation simulation and actual measurement of shock wave operation rules in the pipe, it adopts the correct measures and methods to prevent the reflected shock wave from reaching the nozzle without affecting the work of jet expansion. The air wave tube intercepts, blocks and re-reflects during the return journey, so that it can dissipate energy repeatedly in the rear section of the air wave tube, which strengthens the energy dissipation of the original air wave tube with a lighter dissipation load, and makes the reflection The shock wave travels forward as little as possible to the inlet of the gas wave tube to avoid heating the cooled gas.

Technical scheme of the present invention:

Central choke cavity isolated air wave tube, receiving tube, oscillating tube or dissipation tube, including air wave tube inlet 1, front section of air wave tube 2, middle choke cavity 3, rear section of air wave tube 4, end wave absorbing cavity 5 and the air wave tube support 6; the front section 2 of the air wave tube is connected to one end opening of the middle wave choke cavity 3, and the other end opening of the middle wave choke cavity 3 is connected to the front end of the air wave tube rear section 4, forming a first expansion and then Shrinking flow channel, the tail end of the air wave tube rear section 4 is connected to the only opening of the end wave absorbing cavity 5;

The middle wave choke cavity 3 is a limited-volume container tank arranged in the middle section of the middle wave choke cavity isolation type air wave tube; Large damping effect on reflected shock waves;

The inner diameter or flow cross-sectional area of the front section 2 of the air wave tube is smaller than the inner diameter or flow cross-sectional area of the rear section 4 of the air wave tube, so that the reflected shock wave is not easy to enter the front section 2 of the air wave tube. The flow area of the pulse jet is matched to the outlet size of the jet nozzle.

The space in the middle wave choke cavity 3 or the end wave absorbing cavity 5 is divided into less than 10 spaces connected in series along the axial direction by a transverse partition with a hole in the middle.

The internal flow cross-sectional area of the front section 2 of the gas wave tube is 2 to 10,000 square millimeters in size according to the gas flow rate.

The internal flow cross-sectional area of the air wave tube rear section 4 is matched according to different working conditions, and the flow cross-sectional area is 1 to 15 times the flow cross-sectional area of the air wave tube front section 2 .

The cross-sectional area of flow in the middle choke cavity 3 is matched according to the different working conditions. The cross-sectional area of flow is 1.1 to 300 times that of the front section 2 of the air wave tube, and the length of the middle choke cavity 3 is It is 0.2 to 10 times of the projected width or inner diameter of the middle wave choke cavity 3 .

The hollow cross-sectional area of the terminal wave-absorbing cavity 5 is matched according to its different working conditions. The length is 0.2-10 times of the projected width or inner diameter of the terminal wave-absorbing cavity 5 .

The flow passages of the front section 2 of the air wave tube, the middle wave choke cavity 3, the back section 4 of the air wave tube and the wave absorbing cavity 5 at the end are the inner flow channels of a circular tube, an elliptical tube, a square tube or a rectangular tube, or Grooves and volume cavities are machined on the surface of solid parts, and then sealed by the surface of other solid parts to form embedded grooves or cavities.

The beneficial effects of the present invention are:

1. According to the principle of shock wave reflection and intersection, the reflected shock wave will be buffered in the choke cavity and dissipate a certain amount of energy, and the remaining part will be reflected back to the back section of the gas wave tube, and only a small part can reach the gas wave tube mouth. Thereby reducing adverse effects on the cooled air.

2. The residual reflected shock wave can be reflected and transmitted multiple times between the choke cavity and the wave-absorbing cavity at the end of the tube. On the way, it can encounter the primary shock wave and reflected shock wave formed by the next (or next N) jet flow, resulting in multiple The reverse intersection case. When they intersect, the shock wave intensity is superimposed, which is more conducive to heat transfer and energy dissipation, that is, the choke cavity can make the energy dissipation load move back a lot, reduce the tube wall temperature in the front section of the gas wave tube, and reduce the heat transfer to the refrigerated air in the tube .

3. The flow cross-sectional area of the rear section of the air wave tube is larger than that of the front section, which can make it easier to completely match the nozzle size of the front section with the jet nozzle, and can solve the problem that the original follow-up tube cross-sectional area follows the nozzle, resulting in a small wall area of the air wave tube and energy consumption. Dissipate the contradiction of insufficient energy. More importantly, the reduction in the internal cross-sectional area of the front end of the air wave tube is more conducive to blocking the reflected shock wave from entering the front end of the air wave tube from the choke cavity.

4. The above effects all improve the cooling efficiency of the air wave tube, which can be increased by more than 5% on average. What is more beneficial is that it can significantly increase the trough efficiency value when the jet frequency does not match the tube length (the reflected shock wave has reached or not reached the gas wave tube port in the jet flow), on the one hand, it reduces the difficulty of design matching On the other hand, it can significantly improve the adaptability of air wave refrigeration to variable working conditions.

Description of drawings

The accompanying drawing is a schematic diagram of the structure of the isolated air wave tube in the middle part of the wave choke cavity of the present invention.

In the figure: 1 the entrance of the air wave tube; 2 the front section of the air wave tube; 3 the middle choke cavity; 4 the rear section of the air wave tube;

5 end wave absorbing cavity; 6 air wave tube support; 7 pulse jet.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

A typical implementation of the isolated air wave tube with the middle choke cavity of the present invention is described as follows, but not limited to this implementation:

The central wave choke cavity isolated air wave tube of the present invention, or the central wave choke cavity isolated receiving tube, oscillating tube or dissipative tube, includes the air wave tube inlet 1, the front section of the air wave tube 2, the middle wave choke cavity 3, the air wave tube The rear part of the wave tube 4, the end wave absorbing cavity 5, and the air wave tube support 6; The rear section 4 of the tube, the tail end of the rear section 4 of the gas wave tube is connected to the only opening of the terminal wave-absorbing cavity 5 .

The various parts of the isolated air wave tube with the central wave choke cavity of the present invention include the front section 2 of the air wave tube, the middle wave choke cavity 3, the rear section 4 of the air wave tube, the end wave absorbing cavity 5, and the hollow flow passages thereof, Generally, it is the flow channel in the tube of ordinary round tube, oval tube, square tube and rectangular tube, or an embedded type formed by machining grooves and volume cavities on the surface of a solid part, and then being tightly sealed by the surface of other solid parts. Grooves and cavities.

In the present invention, the space in the central wave choke cavity 3 of the air wave tube isolated from the central wave choke cavity is an entire space or is divided into 10 or less by transverse partitions with openings in the middle and connected in series along the axial direction. space.

The space in the wave-absorbing cavity 5 at the end of the isolated air wave tube with the middle wave choke cavity is a whole space or divided into 10 or less connected spaces arranged in series along the axial direction by several transverse partitions with openings in the middle.

In the isolated air wave tube with the middle choke cavity, the internal flow cross-sectional area of the front section 2 of the air wave tube ranges from 2 to 10,000 square millimeters in size according to the gas flow rate.

For the isolated air wave tube with the middle choke cavity, the internal flow cross-sectional area of the rear section 4 of the air wave tube is matched according to different working conditions, and its range is 1 to 15 times the flow cross-sectional area of the front section 2 of the air wave tube .

The middle choke cavity isolated air wave tube, the internal flow cross-sectional area of the middle wave choke cavity 3 is matched according to the different working conditions, and its range is 1.1 to 300 times the flow cross-sectional area of the front section 2 of the air wave tube; The length of the middle choke cavity 3 is 0.2 to 10 times the projected width or inner diameter of the cavity.

The hollow cross-sectional area of the wave-absorbing cavity 5 at the end of the isolated air wave tube in the middle part is matched according to the different working conditions, and the range is 1.1 to 300 times the flow cross-sectional area of the rear section 4 of the air wave tube; The length of the terminal wave-absorbing cavity 5 is 0.2-10 times of the projected width or inner diameter of the cavity.

The refrigeration principle of the isolated wave tube in the middle part of the present invention is as follows:

The nozzle pulse jet 7 is a pulse jet with a sufficiently small duty cycle, which is generated by a rotary nozzle jet distributor or an air flow oscillator. The pulse jet is suddenly injected into the inlet 1 of the gas wave tube, and the output expansion work compresses the trapped gas in the gas wave tube, and generates compression waves in the gas wave until the shock wave, and quickly transmits the jet energy to the depth and even the rear of the gas wave tube; the shock wave sweeps By raising the temperature of the stagnant gas, the energy is dissipated to the outside through the tube wall, and the energy is exhausted and no longer returns to the jet gas. The jet gas produces a large enthalpy drop due to expansion and work, and the temperature drops to cool.

The middle wave choke cavity 3 completely dissipates the shock wave reflected from the end wave absorbing cavity 5 and is reflected back to the back section of the gas wave tube, and returns to the gas wave tube entrance 1 as little as possible to avoid The heating of the refrigerated air by the reflected shock wave will improve the cooling efficiency, especially the low efficiency when the jet frequency does not match the length of the gas wave tube, will be significantly improved.

The operating parameters of the isolated air wave tube in the middle part of the wave choke cavity of the present invention are as follows:

Pulse jet frequency: 5~500Hz;

Pulse jet duty ratio: 1/1～1/200;

Pressure range of pulse jet: 0.01~40MPa.

Claims (6)

1. A middle part choke cavity isolated type air wave tube is characterized in that the middle part choke cavity isolated type air wave tube comprises a gas wave tube inlet (1), a front section of the gas wave tube (2), a middle part choke cavity ( 3), the rear part of the air wave tube (4), the end wave absorbing cavity (5) and the air wave tube support (6); The opening of the other end of the cavity (3) is connected to the front end of the rear section of the air wave tube (4), forming a flow channel that first expands and then shrinks inside, and the tail end of the rear section of the air wave tube (4) is connected to the end absorbing cavity ( 5) the only opening; The middle wave choke cavity (3) is a container tank with a limited volume arranged in the middle section of the middle wave choke cavity isolated air wave tube; or the middle wave choke cavity (3) is divided into several centrally connected The chamber increases the damping effect on the reflected shock wave; The inner diameter or flow cross-sectional area of the front section of the air wave tube (2) is smaller than the inner diameter or flow cross-sectional area of the rear section of the air wave tube (4), so that the reflected shock wave is not easy to enter the front section of the air wave tube (2), and the front section of the air wave tube (2) The size of the nozzle at the front end matches the flow area of the pulse jet, that is, the outlet size of the jet nozzle; The internal flow cross-sectional area of the front section (2) of the gas wave tube is 2 to 10,000 square millimeters in size according to the gas flow rate; The hollow cross-sectional area of the terminal wave-absorbing cavity (5) is matched according to its different working conditions. The length of the wave cavity (5) is 0.2-10 times of the projected width or inner diameter of the end wave absorbing cavity (5). 2. The middle wave choke cavity isolated air wave tube according to claim 1, characterized in that, the space in the middle wave choke cavity (3) or the end wave absorbing cavity (5) is defined by the transverse direction of the middle opening. The partitions are divided into less than 10 connected spaces arranged in series along the axial direction. 3. The central wave choke cavity isolated air wave tube according to claim 1 or 2, characterized in that, the front section of the air wave tube (2), the middle wave choke cavity (3), the rear section of the air wave tube ( 4) and the flow channel of the end wave absorbing cavity (5) is the flow channel in the tube of a round tube, oval tube, square tube or rectangular tube, or grooves and volume cavities are processed on the surface of the solid part, and then replaced by other solid parts A built-in channel or cavity formed by a tightly sealed surface. 4. The isolated air wave tube with the middle wave choke cavity according to claim 3, characterized in that, the internal flow cross-sectional area of the rear section (4) of the air wave tube is matched according to the different working conditions, The flow cross-sectional area is 1-15 times of the flow cross-sectional area of the front section (2) of the gas wave tube. 5. The central wave choke cavity isolated air wave tube according to claim 3, characterized in that, the cross-sectional area of flow in the middle wave choke cavity (3) is matched according to the different working conditions, and the flow through The cross-sectional area is 1.1-300 times the flow cross-sectional area of the front section (2) of the gas wave tube, and the length of the middle wave-choke cavity (3) is 0.2-10 times the projected width or inner diameter of the middle wave-choke cavity (3). 6. The isolated air wave tube with central wave choke cavity according to claim 4, characterized in that, the cross-sectional area of flow in the middle wave choke cavity (3) is matched according to the different working conditions, and the flow through The cross-sectional area is 1.1-300 times the flow cross-sectional area of the front section (2) of the gas wave tube, and the length of the middle wave-choke cavity (3) is 0.2-10 times the projected width or inner diameter of the middle wave-choke cavity (3).