RU2752332C1 - System for regulating fuel supply to afterburner of turbojet engine - Google Patents

Abstract

FIELD: aircraft engine construction.

SUBSTANCE: invention relates to the field of aircraft engine construction, in particular to systems for regulating the fuel supply to the afterburners of aircraft turbojet engines (turbojet engine with afterburner and turbojet dual-circuit engine with afterburner). A fuel supply system is proposed for the afterburner of a turbojet engine, which contains a control unit, a fuel tank, an afterburner pump, an afterburner fuel flow regulator, and a distributor that directs fuel to the first collector with flame stabilizers, the second collector and the third collector, depending on the gas pressure in the afterburner and the specified engine mode. At the same time, a shut-off valve is installed behind the distributor in the pipeline of the second collector, which opens and closes at the commands of the control unit when the set pressure values in the second and third collectors are reached, providing the fuel flow and pressure necessary for the uniform distribution of the fuel-air mixture along the afterburner section.

EFFECT: task of the invention is providing high quality and uniform spraying of afterburner fuel to improve engine control and increase the stability of the engine in afterburner modes.

1 cl, 2 dwg

Description

The invention relates to the field of aircraft engine building, in particular, to systems for regulating the supply of fuel to the afterburners of aircraft turbojet engines (TRDF and TRDDF).

The organization of the workflow in the afterburners of the TRDDF is fraught with additional difficulties. The mixing of hot gas and cold air flows is carried out in front of the flame stabilizers, and in the cross section of the chamber there is a significant unevenness of the gas flow in temperature, excess air ratio and velocity. This unevenness increases with an increase in the flight speed of the aircraft, since the degree of bypass of the engine increases.

With regard to the forced operation of the engine, the main control problems are the provision and maintenance of the optimal composition of the fuel-air mixture in the afterburner (α _Σopt ). (Korshenko V.N., Mosyagin V.V., On the question of the structure of the gas flow in the front-line device of the afterburner combustion chamber of the TRDDF. // Klimovskie readings-2014: promising directions for the development of aircraft engine building: collection of reports of the international scientific and technical conference. x t. - SPb .: Publishing house "Scythia-print", 2014. - T. 1 - 19 ... 31 p.)

Known afterburner of a two-circuit turbojet engine with mixing flows, containing a housing, a mixer, a front-line device with afterburner nozzles, consisting of a first starting manifold with flame stabilizers, a second and, opening at a given pressure in the second manifold, a third manifold that passes an increasing flow through itself afterburner, designed for uniform distribution of afterburner fuel over the combustion chamber cross-section, (RU # 2641191) The disadvantage of such a feed and mixing system is the partial extinction of the flame in the stabilizers when the third manifold is opened and poor atomization of fuel at low flow rates through the third manifold, which is typical of flights on high altitude (Kotsyubinsky S.V. Increasing the combustion efficiency in the afterburner of the RD-33 bypass turbojet engine // Klimovskie readings-2019: promising directions for the development of aircraft engine building: collection of articles of the scientific and technical conference. - SPb .: Publishing house "Scythia-print", 2019. - From 223 ... 229).

The objective of the invention is to create in the afterburner such a flow rate and pressure that will ensure high-quality atomization of the afterburner and the creation of a homogeneous fuel-air mixture over the entire flow rate range at any point of the section in front of the front afterburner device.

The technical result is to improve engine control and increase the stability of the engine in afterburner modes by ensuring high-quality and uniform atomization of afterburner fuel.

The problem is solved by the fact that a system of fuel supply to the afterburner of a turbojet engine is proposed, which contains a control unit, a fuel tank, an afterburner pump, an afterburner consumption regulator, a distributor that directs, depending on the gas pressure in the afterburner and a given engine operating mode, fuel into the first manifold with flame stabilizers, the second manifold and the third manifold, characterized in that a shut-off valve is installed behind the distributor in the pipeline of the second manifold, which opens and closes at the commands of the control unit when the preset pressure values in the second and third manifolds are reached, providing redistribution of the afterburner fuel consumption between the second and third manifolds for high-quality atomization and distribution of the air-fuel mixture over the afterburner section.

The essence of the invention is illustrated by graphic materials:

FIG. 1. Functional diagram of the system for regulating the fuel supply to the afterburner of a turbojet engine, where

1 - fuel tank,

2 - afterburner pump,

3 - afterburner consumption regulator,

4 - distributor,

5 - afterburner combustion chamber,

6 - engine control lever (throttle),

7 - the first collector (1 TC),

8 - the second collector (2 TC),

9 - the third collector (3 TC),

10 - shut-off valve,

11 - control unit,

12 - pressure sensor in the manifold 8,

13 - manifold pressure sensor 9.

FIG. 2 - Schedule of afterburner fuel distribution over the manifolds from changes in the position of the engine control lever;

In order to reduce the acceleration time, the fuel distributor has a function (N / A) of supplying non-metered fuel for filling when the second and third afterburner manifolds are opened. A shut-off valve is installed behind the distributor in the pipeline of the second manifold, which opens and closes by commands from the control unit. Pressure sensors in the second and third manifolds monitor the pressure during filling, operation and shutdown of the manifolds.

The second and third manifolds spray fuel in front of the flame stabilizers of the first (starting) manifold to ensure uniform distribution of the air-fuel mixture over the afterburner section, which ensures stable engine operation in all afterburner modes.

The operation of the fuel supply control system is as follows.

When the engine control lever 6 is moved to the afterburner zone, the control unit 11 opens the shut-off valve 10 and turns on the afterburner pump 2 to supply fuel from the fuel tank 1 to the afterburner flow regulator 3 and supply fuel through the distributor 4 to the afterburner 5 manifolds.

The afterburner flow regulator 3 forms the flow rate depending on the gas pressure in the afterburner 5 and the mode set by the position of the engine control lever b.

When the engine control lever 6 is set to the "Minimum afterburner" position, the regulator 3 supplies fuel to the manifold 7 and in the inner zone of the stabilizers (not shown) of the afterburner 5 a fuel-air mixture is created with preset pressure and combustion temperature. To ensure stable combustion in the flame stabilizers, the flow rate to the manifold 7 does not change at different engine boost modes.

After ignition and the appearance of combustion in the stabilizers, a signal is generated from the flame sensor behind the collector stabilizers 7 (not shown) and the control unit 11 removes the blocking of the collector 8 from the controller 3.

When the afterburner mode is increased and the engine control lever is set to 6 in the "Full afterburner" position, the afterburner consumption in the manifold 8 increases linearly, and after a signal from the pressure sensor 12 about reaching the set pressure in the manifold 8 (point A on the graph), the control unit 11 removes the regulator 3 blocks the inclusion of the manifold 9 and closes the cut-off valve 10. Distributor 4 redirects the afterburner fuel flow to the manifold 9, creating in it the pressure required for high-quality fuel atomization and stable engine operation at a given mode. With a further increase in flow rate and reaching a predetermined value of pressure in the manifold 9 and the receipt of a signal from the pressure sensor 13 (point B on the graph), the control unit 11 reopens the shut-off valve 10, the distributor 4 divides the total fuel consumption between the manifolds, returning the set fuel share to the manifold 8, and the rest of the fuel is directed to the collector 9.

With the reverse movement of the engine control lever 6 to reduce the afterburner modes, the switching is performed in the reverse order at pressures reduced by 2 ... 3 kgf / cm ² relative to the switch-on pressures, which avoids pulsations in the chamber and ensures stable engine operation at all afterburner modes (Fig. . 2).

Thus, the proposed system for supplying fuel to the afterburner makes it possible to improve the quality of afterburner atomization and the distribution of the air-fuel mixture over the afterburner cross section over the entire flow range at any point in the cross section ahead of the front afterburner device.

Claims (1)

The fuel supply system to the afterburner of a turbojet engine, containing a control unit, a fuel tank, an afterburner pump, an afterburner flow regulator, a distributor that directs, depending on the gas pressure in the afterburner and the preset engine operating mode, fuel to the first manifold with flame stabilizers, the second manifold and the third manifold, characterized in that a shut-off valve is installed behind the distributor in the pipeline of the second manifold, which opens and closes according to the commands of the control unit when the preset pressure values in the second and third manifolds are reached, providing the fuel consumption and pressure necessary for high-quality fuel atomization and distribution air-fuel mixture over the afterburner section.

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