RU2758665C1 - Method for manufacturing a plate heat exchanger - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention relates to methods for manufacturing plate heat exchangers for small-sized gas turbine engines (SSGTE) and installations (SSGTI) of a complex cycle. The method is characterized by the fact that by stamping with a hood, identical plates with peripheral edges and flanged edges are formed, heat exchange elements are assembled by pairwise fixing and welding the peripheral edges of the plates together with laser welding, the inlet and outlet pipes are connected and placed in the housing, and when manufacturing the heat exchanger plates, the width of the peripheral edges is selected taking into account the deformation of the edges during stamping, after stamping, the flanged edges are additionally corrected and the peripheral edges are cut off, and before welding the heat exchange elements, fixing inserts are installed in the channels for the supply and removal of the coolant, which are removed at the end of welding.

EFFECT: increase in the accuracy of the geometric dimensions of the heat exchange elements by reducing deformations during the manufacture of the heat exchanger.

1 cl, 6 dwg

Description

The invention relates to a device for generating, amplifying, modulating, demodulating or converting frequency, using stimulated emission of electromagnetic waves, and in particular to repetitively pulsed fiber lasers with passive Q-switching of the cavity.

Pulsed-periodic fiber lasers are used to process various kinds of materials for marking, engraving, medicine, ranging, spectroscopy and other applications.

The main advantages of repetitively pulsed fiber lasers over others are: high quality of radiation, high efficiency, compactness and reliability.

Known technical solution described in the patent for utility model No. 112520, publ. 01/10/2012, IPC H01S 3/067, under the name "Fiber laser", containing a power supply and an emitter including an optically coupled active element in the form of an active fiber light guide and a diode pump source, while the first output of the power supply is electrically connected to the input a radiator containing a thermal sensor, the output of which is electrically connected to the input of the power supply, at least one electrical heating elements, the power leads of which are electrically connected to the second output of the power supply.

The disadvantages of this device include:

- lack of description of the laser circuit and its efficiency;

- the presence of a plate with several heating elements for heating the active element, which complicates the design and increases the weight and size characteristics.

Known all-fiber laser system for generating laser pulses in passive Q-switching, described in patent RU No. 2 548 940, IPC H01S 3/067, publ. April 20, 2015, containing two fiber cavities - short-wave and long-wave, which are resonators, respectively, of short-wave and long-wave fiber lasers formed by their own pairs of fiber Bragg gratings, while the outside-pumped short-wave resonator is a pump laser for the long-wave resonator.

The disadvantages include the generation of radiation at two wavelengths and low radiation energy, which was 40 mJ, and the peak radiation power with a pulse duration of 105 was not 317 W. There is also a need in the invention to synchronize the modulation frequency and pump current power with the laser pulse repetition rate.

The closest in technical essence to the invention and selected as a prototype of the device is the technical solution described in patent RU No. 2717254, IPC H01S 3/067, H01S 3/06, publ. 03/19/2020 entitled "Fiber laser for pumping active elements", including an optically coupled active element in the form of an active fiber light guide, a diode pumping source equipped with emitters, fiber-optic pump combiners, a resonator formed by selective mirrors made in the form of fiber Bragg gratings, fiber radiation output equipped with a crystal tip.

The disadvantages include the ability to work only in continuous mode.

The objective of the present invention is to improve operational characteristics, namely, to generate laser radiation at only one wavelength, to increase the energy and peak radiation power, efficiency and stability of the repetitively pulsed mode of operation.

The technical result is to ensure

- generation of radiation at only one wavelength;

- increasing the output radiation power;

- increasing the stability of the pulse-periodic mode of operation;

- implementation of radiation output through an active fiber with population inversion, providing amplification of radiation;

- pumping the active fiber of the resonator by the luminescence of the fiber, which is pumped by laser modules equipped with emitters.

The specified technical result is achieved by the fact that an all-fiber repetitively pulsed laser including an optically coupled active element in the form of an active fiber light guide, a diode pumping source equipped with emitters, fiber-optic pump combiners, a resonator formed by selective mirrors made in the form of fiber Bragg gratings, the fiber output of radiation, equipped with a crystal tip, according to the invention, is equipped with at least one additional source of diode pumping in the form of laser modules equipped with emitters, while the resonator is connected through an output selective mirror to an active optical fiber made in the form of an active fiber with population inversion for ensuring pumping of the cavity and amplification of the output radiation.

The analysis of the state of the art carried out by the applicant, including a search for patent and scientific and technical sources of information and the identification of sources containing information about analogues of the claimed invention, made it possible to establish that the applicant did not find an analogue characterized by features identical to all essential features of the claimed invention, but the definition from the list identified analogs of the prototype, as the closest analogue in terms of the totality of features, made it possible to identify a set of significant in relation to the technical result perceived by the applicant of the distinctive features in the claimed object set forth in the claims.

Consequently, the claimed invention meets the requirement of "novelty" under the current legislation.

To check the compliance of the claimed invention with the condition of the inventive step, the applicant conducted an additional search for known solutions in order to identify features that match the distinctive features of the prototype of the claimed invention, the results of which show that the claimed invention does not follow explicitly for a specialist from the prior art.

Therefore, the claimed invention meets the requirement of "inventive step".

The proposed technical solution is illustrated in the following drawings:

in fig. 1 is a schematic diagram of an all-fiber repetitively pulsed laser;

in fig. 2 shows a diode pumping source;

in fig. 3 shows a fiber output of radiation with a quartz tip;

in fig. 4 shows an example of an oscillogram of a sequence of pulses when using thulium active fibers;

in fig. 5 shows the dependence of the pulse repetition rate on the pump radiation power.

The following symbols have been introduced in the drawings:

1 and 2 - active fiber;

3 and 4 - fiber Bragg gratings;

5 - cladding mode filter;

6 - pump combiner;

7 - laser diode modules;

8 and 9 - fiber output of radiation;

10 - emitter;

11 - output fiber;

12 - crystal tip.

The functional diagram of an all-fiber repetitively pulsed laser (Fig. 1) contains an active fiber 1 and 2, for example, thulium, fiber Bragg gratings 3 and 4 with high reflectance (HR) and high transmittance (HT), for example, with a resonant wavelength 1977 nm, cladding mode filter 5, pump combiner 6, laser diode modules 7, for example, at a wavelength of 793 nm, fiber output 8 and 9 (End-Cap), emitter 10, output fiber 11, crystal tip 12, for example, quartz.

The active fiber 1 is pumped along the cladding by laser diode pump modules 7 equipped with emitters 10 (Fig. 2). To protect the circuit from unabsorbed pumping, a cladding mode filter is used. high reflectivity at the operating wavelength, respectively. To prevent the effect of reflected radiation on the operation of the circuit and to reduce the power density, radiation from the fiber optical path is output through the fiber output 8 and 9 equipped with a quartz tip 12 (Fig. 3) welded to the optical fiber 11 (Fig. 3). The device works as follows.

The principle of operation of the proposed technical solution in the proposed scheme is based on the modulation of the gain in the resonator formed by the section of the active non-pumpable fiber 2 and two fiber Bragg gratings 3 and 4 and modulation of the gain in the pumped active fiber 1.

At the initial moment of time in the active fiber 1, pumped by the pump module 7 through the combiner 6, the accumulation of inversion and re-emission in the luminescence band of the active fiber 1 occurs. The subsequent developing generation of laser radiation in an unpumped cavity is of a pulsed nature. Fiber Bragg gratings 3 and 4 of the resonator are positioned so that the lasing radiation is directed towards the pumped active fiber 1. The lasing pulse propagating through the pumped section of the active fiber 1 is accompanied by amplification and additional removal of the inversion in the active pumped medium, which makes it possible to obtain high efficiency laser and improves the stability of the laser in pulsed mode.

The enterprise tested an all-fiber repetitively pulsed laser consisting of thulium fibers 1 and 2, a diode pump source 7 equipped with single emitters 10, a fiber-optic pump combiner 6, a resonator formed by selective mirrors 3 and an output 4 made in the form of fiber Bragg gratings 3 and 4 with a resonant wavelength of 1977, fiber output 8 and 9 with a quartz tip 12.

Experimental studies have shown that the proposed scheme of an all-fiber repetitively pulsed laser provides stable generation of radiation pulses (Fig. 4). In this case, the pulse repetition rate depends on the pump power (Fig. 5).

The claimed technical solution made it possible to reduce the number of elements of the optical path, to obtain stable and stable generation of laser radiation in a repetitively pulsed mode, while amplifying the radiation in the active fiber, which provides pumping of the active fiber of the resonator. The average radiation power was 8 W, the radiation energy was 88 mJ, and the peak power with a pulse duration of 100 was not 880 W.

For the claimed invention in the form as it is described in the claims, the operability of the all-fiber repetitively pulsed laser and the ability to achieve the specified technical result have been experimentally confirmed. Therefore, the claimed invention meets the condition of "industrial applicability".

Claims (1)

All-fiber repetitively pulsed laser, including an optically coupled active element in the form of an active fiber light guide, a diode pumping source equipped with emitters, fiber-optic pump combiners, a resonator formed by selective mirrors made in the form of fiber Bragg gratings, a fiber radiation output equipped with a crystal tip characterized in that it is equipped with at least one additional source of diode pumping in the form of laser modules equipped with emitters, while the cavity is connected through an output selective mirror to an active fiber made in the form of an active fiber with population inversion to ensure pumping of the cavity and amplification output radiation.

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