Linear MHD generator with boundary layer suction

Abstract

The application discloses a linear type MHD generator with boundary layer suction, which comprises a power generation channel, the cross section of the power generation channel is rectangular, two sides of the power generation channel are provided with rectangular through grooves, suction electrodes are fixedly installed in the rectangular through grooves through cover plates, the suction electrodes are conductive flat plates provided with cavities, air passages communicated with the power generation channel are arranged on the cavities, exhaust ports are arranged on the cover plates, one end of the power generation channel is connected with an exhaust connecting section through an adapter section, the other end is connected with a nozzle, corrugated pipes communicated with the exhaust connecting pipes are arranged on the exhaust ports, and magnets are arranged on both sides of the power generation channel. When high-temperature air flow expanded and accelerated by the nozzle passes through the power generation channel, the boundary layer with low temperature and low flow speed near the wall surface is sucked into the suction vacuum cavities on both sides, low-energy fluid is discharged through the exhaust ports on the exhaust cover plates, the air flow temperature on the electrode surface in the channel is increased, the conductive capacity of the power generation working medium is enhanced, and greater induced electromotive force is generated.

Description

TECHNICAL FIELD

[0001] The present application relates to a linear MHD generator with boundary layer suction, and belongs to the field of generators. BACKGROUND

[0002] High power pulse power supply can produce 10-10 -9 J or more energy in 10 9 s duration, which has urgent application requirements in the fields of high power laser, particle beam weapon, microwave weapon, electromagnetic emission and high power emergency communication. However, the traditional capacitor and inductor energy storage high power pulse power supply has been unable to meet the extremely high current and voltage input requirements of high-tech equipment due to the limitation of its volume and energy storage density. The MHD generator has unique advantages, such as no rotating parts, large single machine capacity and high efficiency, no intermediate energy storage element, direct energy transmission from the power generation device to the load, no need for high-power switches, fast start speed, etc. It has important application value in the fields of national defense science and technology and industrial and civil use.

[0003] The linear MHD generator has a relatively simple structure and is convenient to apply in many types of pulse power supplies. According to Faraday's law of electromagnetic induction, the high-temperature conductive fluid passes through the magnetic field perpendicular to the flow direction at a certain speed, cuts the magnetic induction lines in the rectangular power generation channel, and thus generates an induced electromotive force on the electrodes. However, in the case of non-isothermal flow, when the fluid flows through the wall of the power generation channel, a thin gas layer with a temperature gradient is formed near the boundary due to cooling. The temperature distribution of the boundary layer close to the electrode surface is uneven and much lower than that of the central mainstream, which changes the electrical conductivity of the conductive gas between the electrodes and reduces the electrical conductivity of the working medium, greatly affecting the power and working stability of the MHD generator. Although certain research results have been achieved in the development of linear MHD generators at home and abroad, there are few experimental devices for the influence of the temperature boundary layer of the power generation channel. Boundary layer suction is an effective flow control method. The boundary layer is discharged outside the flow channel through the form of holes or slots in the wall, so that the high-temperature fluid occupies the wall again, improves the temperature of the wall-attached fluid, and meets the current needs of exploration, research and development of MHD generators. SUMMARY

[0004] The present application provides a linear MHD generator with boundary layer suction, which can overcome the deficiencies in the prior art. When the high-temperature gas flow accelerated by the nozzle expands, the low-temperature and low-flow-rate boundary layer near the wall is sucked into the vacuum cavity on both sides through the exhaust port on the exhaust cover plate, the low-energy fluid is discharged, the temperature of the gas flow on the electrode surface in the channel is improved, the electrical conductivity of the power generation working medium is enhanced, and a greater induced electromotive force is generated.

[0005] Technical solution: To solve the above technical problems, the boundary layer suction linear MHD generator comprises a power generation channel, the cross section of the power generation channel is rectangular, the upper and lower sides of the power generation channel are provided with rectangular through grooves, suction electrodes are fixedly installed in the rectangular through grooves through cover plates, the suction electrodes are conductive flat plates provided with cavities, air passages are arranged on the cavities and communicate with the power generation channel, and exhaust ports are arranged on the cover plates; one end of the power generation channel is connected with an exhaust connection section through an adapter section, the other end is connected with a nozzle, corrugated pipes are arranged on the exhaust ports and communicate with the exhaust connection pipes, and magnets are arranged on both sides of the power generation channel; when the high-temperature gas flow expanded and accelerated through the nozzle passes through the power generation channel, the boundary layer with low temperature and low flow rate near the wall surface is sucked into the suction vacuum cavities on both sides, and the low-energy fluid is discharged through the exhaust ports on the cover plates; the nozzle, the power generation channel, the adapter section and the exhaust connection section are sequentially connected and sealed to form a power generation main circuit, and the area of the suction bypass exhaust port must be greater than the sum of the areas of the rectangular suction grooves on the electrodes or the areas of the suction holes.

[0006] Preferably, the air passage is an inclined rectangular groove, and the air passage is close to the air inlet end of the power generation channel.

[0007] Preferably, the air passage and the lower wall surface form an angle of 5°-20°.

[0008] Preferably, the air passage is a plurality of suction holes with a radius R, and the hole center distance is 2R-6R.

[0009] Preferably, the corrugated pipe is connected with the exhaust port through an insulating connection section.

[0010] Beneficial effects: Compared with the prior art, the boundary layer suction linear MHD generator has the following advantages:

[0011] 1. The suction groove hole structure is adopted to separate the boundary layer from the main flow area, the uniformity and stability of the airflow temperature distribution in the longitudinal direction are enhanced, and the electrical conductivity of the power generation working medium between the electrodes is improved.

[0012] 2. A vacuum cavity is designed between the suction electrode and the exhaust cover plate, the negative pressure on the other side of the groove hole is conducive to sucking out the surface layer gas when the airflow flows through the electrode surface, and the area of the exhaust port is greater than the area of the suction groove hole, so that the airflow jamming in the vacuum cavity is avoided.

[0013] 3. An insulating adapter section is designed and adopted, the insulation effect is good, and the electrical conductivity between the electrode and other structures of the MHD generator is ensured. Brief description of drawings

[0014] Figure 1 It is a front view of the structure of the application.

[0015] Figure 2 It is a top view of the structure of the application.

[0016] Figure 3 This is a schematic diagram of the present invention.

[0017] Figure 4 This is a schematic diagram of the suction groove electrode.

[0018] Figure 5 This is a cross-sectional view of the electrode in the suction groove.

[0019] Figure 6 This is a schematic diagram of the suction port electrode.

[0020] Figure 7 This is a cross-sectional view of the suction port electrode.

[0021] Figure 8 This is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] like Figures 1 to 8 As shown, the linear magnetohydrodynamic generator with boundary layer suction of the present invention includes a power generation channel with a rectangular cross-section. Rectangular through-slots are provided on the upper and lower sides of the power generation channel. Suction electrodes are fixedly installed in the rectangular through-slots via cover plates. The suction electrodes are conductive flat plates with concave cavities. Air passages communicating with the power generation channel are provided on the concave cavities. Exhaust ports are provided on the cover plates. One end of the power generation channel is connected to an exhaust connection section via a transition section, and the other end is connected to a nozzle. A corrugated pipe is provided on the exhaust port, communicating with the exhaust connection pipe. Magnets are provided on both sides of the power generation channel. When the high-temperature airflow, accelerated by the expansion of the nozzle, passes through the power generation channel, it draws in a boundary layer with lower temperature and velocity near the wall in the vacuum chambers on both sides. The low-energy fluid is discharged through the exhaust ports on the cover plates. The nozzle, power generation channel, transition section, and exhaust connection section are sequentially connected and sealed to form the main power generation circuit.

[0024] In this invention, the air passage is an inclined rectangular groove with an inclination angle of 5° to 20°, and the air passage is located near the air inlet end of the power generation channel. Alternatively, the air passage is a plurality of suction holes with a radius R, and the center distance between the holes is 2R to 6R. The corrugated pipe is connected to the exhaust port through an insulated connecting section.

[0025] In the present application, the nozzle is a converging-diverging Laval nozzle, the flow area is first reduced and then expanded along the flow direction. Action: The high-temperature and high-pressure power generation medium is expanded and accelerated from subsonic speed to supersonic speed and then enters the power generation channel, converting the available thermal energy of the gas flow into kinetic energy. The Mach number of the outlet gas flow is determined by the ratio of the outlet area to the throat area, and the flow rate is controlled by the size of the nozzle throat area. The expansion ratio of the nozzle can be changed as required to obtain power generation medium with different speeds, and the throat area is changed to control the time of gas flow. The cross section of the power generation channel is rectangular, the inlet size is the same as the outlet of the nozzle, the channel profile is slightly expanded to reduce the influence of the increasing boundary layer thickness, and rectangular holes are opened on the opposite positions of the upper and lower sides for installing the pumping electrode. It is made of insulating material. Action: The place where the power generation medium cuts the magnetic induction line.

[0026] In the present application, the overall structure of the pumping electrode is a conductive flat plate with a recessed cavity, and the outer edge of the flat plate is spaced apart from the through hole connected to the lower end of the power generation channel and the threaded hole connected to the upper end of the exhaust cover plate. According to the different structures of the recessed cavity, it is divided into two types of slot electrodes and hole electrodes, the slot electrode has an inclined rectangular slot at the bottom of the recessed cavity near the air inlet end, the inclined angle with the lower wall surface is 5°~20°, and the wall surface on one side of the air inlet end is removed; while the hole electrode has uniformly distributed pumping holes with the same radius R at the bottom of the recessed cavity near the air inlet end, and the hole center distance is 2R~6R. The electrode is made of conductive material. Action: Two ends of the conductive gas cutting the magnetic induction line to lead out current, which can be connected to external load through wires.

[0027] In the present application, the cover plate structure is a flat plate with exhaust holes and vacuum flanges. Action: It forms a vacuum cavity with the pumping electrode, and the thin layer of gas pumped into the vacuum cavity is discharged into the outlet of the power generation channel through the exhaust holes. The two ends of the insulating connecting section are hollow connecting sections with vacuum flanges, which are made of insulating material. Action: Insulate the electrode from the pumping bypass. The adapter section is mainly used to connect the rectangular cross-section power generation channel and the downstream circular cross-section exhaust connecting section. The exhaust connecting section: used to connect the power generation main path and the pumping bypass, and the downstream can be connected with the vacuum tank.

[0028] The linear MHD generator with boundary layer pumping of the present application, wherein the nozzle, the power generation channel, the adapter section, and the exhaust connecting section are sequentially connected and sealed to form the power generation main path; the pumping electrode, the exhaust cover plate, the insulating connecting section, and the bellows are sequentially connected to form the pumping bypass; the power generation channel is placed in a vertical magnetic field; the pumping electrode is symmetrically arranged on the side of the power generation channel parallel to the magnetic induction line, and is closed and attached to the exhaust cover plate to form a pumping vacuum cavity; the bellows is connected to the insulating connecting section and the exhaust connecting section through the vacuum flanges on both sides, respectively, to discharge the thin layer of gas flowing into the vacuum cavity. The entire MHD generator has a plasma generator at the inlet, and the plasma working medium for power generation can be generated by fuel combustion, explosive explosion, laser heating, or electric arc discharge, etc., and the outlet can be connected with a vacuum tank.

[0029] The above merely describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A linear MHD generator with boundary layer suction, characterized in that: The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves.

2. The straight linear MHD generator with boundary layer suction according to claim 1, characterized in that: The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves.

3. The straight MHD power generator with boundary layer suction according to claim 1, characterized in that: The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves.

4. The straight MHD power generator with boundary layer suction according to claim 1, characterized in that: The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves.

5. The straight MHD power generator with boundary layer suction according to claim 1, characterized in that: The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through grooves. The power generation channel has a rectangular cross section, and upper and lower sides of the power generation channel are provided with rectangular through gro

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