RU2478528C2 - Method of defining target fuel residue in slipper fuel tank in fueling - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to aircraft engineering. proposed method allows using fuel meters for defining preset fuel residue in slipper fuel tank (SFT) to lift restrictions on flying aircraft. Basic fact of reaching preset amount of fuel residue in SFT is defined to calculate fuel amount to be consumed thereafter to reach preset residue. Here, fuel meter readings are recorded and tracked unless magnitude exceeding fixed one by preset amount is reached. Thereafter signal is generated to warn about reaching preset fuel residue. Said basic fact represents the beginning of SFT residue consumption. Fuel pumps for transfer of fuel from SFT into internal tank are additionally used at the beginning of SFT fuel consumption to record internal tank fuel meter readings. Here, fuel meter readings should stay in preset range. Said basic fact may be set as the end of tank fuel consumption before SFT fuel consumption. Onboard computer is used to define occurrence of basic fact, to record and track fuel meter readings and to generate signal. Said signal is displayed by appropriate indicators.

EFFECT: higher validity and reliability.

7 cl, 2 dwg

Description

The invention relates to the field of aviation, in particular to the fuel systems of aircraft.

There are various fuel tanks on board the aircraft that are located both inside the wing and fuselage, and on special suspension devices (Aviation // Encyclopedia. Moscow. Scientific Publishing House "Big Russian Encyclopedia", N.E. Zhukovsky Central Aerodynamic Institute , 1994, articles "Fuel System" and "Fuel Tank", pp. 568-570). When flying to a range exceeding the calculated one, suspended fuel tanks (PTB) are used, which impair the aerodynamic drag and flight performance of the aircraft (ibid., As well as Leshchiner L.B., Ulyanov I.E. Design of fuel systems of aircraft. M .: Mechanical engineering, 1975, p. 325). The purpose of using the PTB is to increase the range and duration of the flight.

The use of PTB imposes some limitations on aerobatics (in particular, permissible overloads, maneuvers, flight speed, etc.). These deteriorations can play a decisive role in the combat use of the aircraft, therefore, in such situations, the PTB is discarded. As a rule, during combat use, a PTB discharge is carried out either at the discretion of the pilot or after the fuel has been exhausted from the tank. In normal operation, for example, when driving a plane, no discharge is made. In reality, most often the PTB is reset when it receives a signal about its emptiness - "PTB is empty."

Production from the PTB is carried out by pumping fuel to replenish the internal tank at all possible modes of fuel consumption along the flight profile with the PTB.

One of the restrictions when flying with a PTB is to limit the speed of an airplane due to wing flutter due to the increased load on it from a PTB. However, during the flight, as fuel is generated from tanks installed under the wing, speed limits can be reduced before the “PTB empty” signal appears. By calculation it can be established at which fuel supply in the PTB it is permissible, for example, with a fuel remaining half of the tank, 500 kg, etc. In this regard, it becomes important to determine whether the amount of fuel in the PTB during its production exceeds a certain value.

In aviation, fuel consumption is monitored using fuel metering systems. Fuel metering systems are known in which the fuel supply value is determined using sensors located directly in the tanks, and flow meter systems in which the fuel supply is determined by the flow rate measured by flow meters installed in pipelines supplying fuel to the engines by integrating the instantaneous fuel consumption and subtracting this values from the initial stock (see, for example, Domotenko N.T., Kravets A.S. et al. Aviation power plants. M .: Transport, pp. 178-180). Due to the low reliability of these systems, both fuel metering and flow meter systems are used, one of which is duplicate.

The determination of the amount of fuel in aircraft tanks is usually carried out using sensors installed in the tanks and measuring the level of fuel - sensors of the fuel meter. However, installing the sensor in a dumped hanging tank is irrational, because they will be lost with the tank.

It is known to use as sensors a fixed amount of fuel in the PTB suspension sensors and reset sensors PTB (utility model of the Russian Federation No. 22463). The disadvantage of this approach is that the suspension sensors determine only the fact of the presence or absence of a tank, but not the amount of fuel.

Determining the fact of the full development of a suspension tank without placing sensors in it is possible using the device for monitoring the end of fuel production from aircraft suspended dumped tanks, described in a.s. USSR No. 197409. Fuel is displaced by compressed air from the PTB into the internal tank through a pipeline. The device is connected to this pipeline and consists of a sleeve with drain and drain holes. A sensor is installed inside the sleeve, which generates a signal when, as a result of emptying the PTB, the sleeve is filled with air instead of fuel.

Closest to the invention is a method for determining the achievement of a zero fuel residue in the PTB (detecting the fact of emptying the PTB), which consists in using the device as. USSR No. 197409 or similar, and receive a signal about emptying the PTB upon reaching almost zero fuel level (with an error due to the design). This solution is not acceptable for determining values in the range from “tank full” to “tank empty”.

The objective of the invention is to provide the ability to determine the achievement of a predetermined supply of fuel in the PTB inside the interval from “PTB is full” - “PTB is empty” without the installation of additional fuel measuring sensors in these tanks or other additional fuel measuring equipment.

The problem is solved by a method for determining the achievement of a given fuel residue in an outboard fuel tank during its generation, in which the base event is preliminarily determined and the amount of fuel that must be consumed after the basic event before reaching the predetermined remaining fuel in the outboard fuel tank when the base events record the flow meter reading and then monitor the flow meter readings until a value exceeds the recorded reading by the mentioned amount Fuel GUSTs, on reaching this value form the signal on achieving a predetermined fuel residue in fuel tank suspended.

As a basic event, the start of production of said outboard fuel tank may be selected.

With this choice of a basic event, to increase reliability, devices are used that provide fuel transfer from the outboard fuel tank to the inner tank while maintaining the fuel level in the inner tank in a certain range, and additionally, when the outboard fuel tank starts producing, the fuel tank meter reading is recorded during the outboard fuel tank is monitored to ensure that the fuel gauge is within this defined range.

As a basic event, the end of the development of the fuel tank, which is generated immediately before the said outboard fuel tank, can be selected.

Determining the fact of the onset of the basic event, fixing and tracking the flow meter, the formation of the said signal is carried out using a calculator.

The mentioned signal reflect means of indication.

The proposed method allows, based on the indications of the general fuel measuring equipment, to determine whether the specified fuel balance in the PTB has been reached during its development, which allows the pilot to decide on the possibility of removing some restrictions (increase speed, perform maneuvers, etc.)

The invention is illustrated by figures.

Figure 1 shows a schematic diagram of an aircraft fuel system in which the proposed method can be implemented.

Figure 2 shows, on an enlarged scale, an inkjet level indicator that allows fuel to be pumped from an outboard fuel tank in a certain range of fuel level in the inner tank.

The proposed method can be implemented due to the fact that in modern airplanes, the transfer of fuel from an outboard tank to an internal tank begins at a time when the amount of fuel in an internal tank equipped with fuel gauge sensors drops to a predetermined level. At the same time, during the transfer of fuel from the PTB, the transfer of fuel to the internal tank from other tanks does not occur.

It is also assumed that fuel consumption by engines (per unit time) does not exceed the rate of fuel transfer from the PTB (the amount of fuel pumped per unit time to the internal tank).

Next, with reference to the positions of figures 1 and 2, the principle of operation of devices for pumping fuel from the PTB is described.

To implement the method, known devices for generating (pumping) fuel from outboard fuel tanks (5) or (6) into the inner tank (1) in a certain range of fuel level in the inner tank (1) can be used. Fuel is pumped through pipes (2) connecting the PTB (5) or (6) to the internal tank (1), the outlet of which is blocked by valves (7) or (8) with hydraulic control from the jet level indicators (SIU) (10) or (eleven). SIUs (10) and (11) are located in the inner tank (1) at the levels at which this PTB (5) or (6) should be developed, one for each of the PTBs. In the SIU (10) or (11) there are (see Fig. 2) an input fitting (22) and a receiving fitting (23).

Transfer, for example, from PTB (5) is as follows (see figure 1). From an outboard fuel tank (PTB) (5), fuel is supplied through a pipe (2) to a controllable valve (7) in an internal tank (1). In the SIU (10), fuel from an external source is supplied under pressure to the inlet fitting (22) and passes into the receiving nozzle (23) if the cavity between the fittings (22) and (23) is not filled with fuel. In this case, under the pressure of the jet, the valve (7) opens and the fuel from the PTB (5) enters the inner tank (1). In this case, the fuel level in the tank (1) rises and fills the cavity between the fittings (22) and (23). The jet pressure drops and the valve (7) closes. With some emptying of the tank (1) (due to the transfer of fuel from the tank (1) to the supply tank (3)), the fuel level in the tank (1) drops again and the cycle repeats again: SIU (10) opens the valve (7), and the fuel again is pumped from the PTB (5), its level rises, the SIU (10) closes the valve (7), and the pumping stops. Such cycles are repeated until the PTB is emptied (5).

After emptying the PTB (5), the fuel level in the tank (1) continues to drop (due to the transfer of fuel from the tank (1) to the supply tank (3)) until it reaches the level where the next SIU (11) is installed, which controls the output from the next outboard fuel tank (6).

In the process of production from PTB (5) or (6) or other PTB, which are not shown in FIG. 1, the fuel level in the tank (1) is relatively stable. The causes of some fluctuations in the fuel level may be the cyclic functioning of the SIU and the evolution of the aircraft described above. The process of pumping fuel from the next PTB takes place similarly: it begins when the fuel level in the tank (1) reaches the level of the SIU location corresponding to this PTB or a pair of symmetrical PTBs, and then for the period of generation of the PTB the fuel level in the tank (1) is approximately stabilized in a certain range (determined by the SIU parameters).

In the inner tank (1) there are also fuel gauge sensors (14) for monitoring the fuel level in the tank (1).

Figure 1 also shows a consumable tank (3), into which fuel is pumped from the inner tank (1) before entering the engines. When pumped to engines, fuel passes through a flowmeter sensor (15).

A method for determining the achievement of a given fuel balance in an outboard fuel tank during its production is as follows.

Preliminarily (in preparation for the flight or earlier), the basic event is determined and, depending on this event, the amount of fuel Q, which must be consumed by the engines after the basic event before reaching the specified fuel balance in the outboard fuel tank (for example, (5) or (6)).

As a base event, for example, the following is selected:

- starting the engines (this option can give a big error due to the length of the time interval between starting the engines and the beginning of the development of the PTB),

- the beginning of the development of this outboard fuel tank,

- the end of the development of the fuel tank, which is produced immediately before the said outboard fuel tank (may be either another outboard tank, or internal),

- another event.

If the base event is the start-up of the suspension of the fuel tank, a calculated amount of fuel Q is equal to the initial amount of fuel in the suspension tank About _{PTB beginning} (the weight of fuel, produced from PTB of full refueling until emptying is known from manuals - OM) minus Q _ost - the value of the remaining fuel, the achievement of which they want to determine the proposed method (Q = Q _{PTB nach} -O _ost ).

If the basic event is the end of the development of another fuel tank, to this difference it is necessary to add the amount of fuel ΔQ from the inner tank (1), and maybe from some other tanks that should be pumped to the engines between the end of the development of another fuel tank and the beginning of the development of this outboard fuel tank (Q = О _{ПТБ beg} -O _ost + ΔQ).

Since the flow meter has an error (δ _p ), it is advisable to add δ _p Q to make a decision on removing the limit on the amount of leaking fuel Q. With this error taken into account, the remaining fuel in the tank may be slightly less than that allowed to remove the restriction, but this will only to greater reliability (for the purpose of removing restrictions).

Upon the occurrence of a basic event in flight, the readings of the flow meter P ₁ are recorded.

Then, the flowmeter readings are monitored until a value exceeds the recorded reading P ₁ by the amount of fuel Q calculated as described above (i.e., the amount of fuel that must be consumed by the engines after the base event before reaching the specified fuel balance in the outboard fuel tank ) Upon reaching this value (i.e., when the flowmeter readings are equal to P ₁ + Q), a signal is generated that the predetermined fuel remaining in the outboard fuel tank has been reached.

Preferably, if devices are used that transfer fuel from the outboard fuel tanks to the inner tank while maintaining the fuel level in the inner tank in a certain range. This range of changes in the amount of fuel from the start of turning on the control sensor of the shut-off device for supplying fuel from the PTB to its shutdown when the fuel level is restored after the tank is refilled due to pumping from the PTB (hysteresis) is also known from RE.

Then, in order to increase the reliability of the method, the readings of the fuel gauge of the inner tank are additionally recorded at the time of starting the production of the outboard fuel tank and, during the development of the outboard fuel tank, they are monitored so that the readings of the fuel gauge are in this certain range (i.e., differ from the recorded ones by no more than a certain amount) . This allows you to timely detect an emergency.

Determining the fact of the occurrence of the basic event, fixing and tracking the flow meter, generating a signal about the achievement of a given fuel balance in the outboard fuel tank is carried out using a calculator.

This signal is immediately reflected by means of indication so that the pilot can make a decision about the possibility or impossibility of removing the restrictions caused by the fullness of the PTB.

Example 1: Implementation of the determination of the achievement of a given fuel balance in the PTB (5) and (6) in the case of the aircraft fuel system, the circuit diagram of which is shown in figure 1. The main event is the beginning of the development of the PTB (5) for the tank (5), the beginning of the development of the PTB (5) for the tank (6).

The fuel system includes:

- internal tanks (1), (3), (4);

- suspended tanks installed under the wing (PBC) (5);

- ventral suspension tank (FPB) (6);

- pipeline (2), through which fuel from (5) or (6) is pumped into the tank (1);

- controlled valves (shut-off devices) (7) and (8), opening at the beginning of fuel production from the PTB, according to the order of fuel production;

- level sensors (SIU) (9) of the internal tank (4), which are triggered upon reaching level I, opening the fuel outlet from the tank (4);

- level sensors (SIU) (10), (11), which are triggered, opening the exit from the pipeline (2) to the tank (1) upon reaching the corresponding level II or III;

- sensor-detector (12), issuing a signal "tank (4) is empty";

- pumps (13) that pump fuel from tank to tank or pump it to the engine;

- fuel gauge sensors (14);

- flowmeter sensor (15);

- a non-return valve (16) that prevents the flow of fuel from the tank (1) into the PTB.

Installing the SIU (9), (10), (11) in one tank (1) at certain levels provides a given sequence of fuel production in accordance with the centering requirements.

Before the flight, for each of the PTBs (5) and (6), it is calculated (as the difference between the initial fuel supply in the PTB and the given fuel balance in the PTB) the amount of fuel Q ₅ and O _6, respectively, which must be consumed (i.e., go through flowmeter sensor (15)) from the corresponding base event to reaching the specified fuel balance in the PTB (5) and (6).

When the plane is flying, fuel is generated in the following order:

1. First, a tank (1) is produced to the SIU installation level (9) - (level I). In this case, a known amount of fuel ΔQ _{0 is} generated from the tank (1). Fuel production starts from the tank (4). In the process of fuel consumption for the engine, the fuel level in the tank (1) is maintained in a certain range near the SIU (9) until the tank (4) is empty, then a signal is sent from the signaling sensor (12) that the tank (4) is empty.

2. Then the tank (1) undermines again to the SIU installation level (10) (level II) - the sensor for controlling the output from the tank (5). In this case, a known amount of fuel ΔQ _{1 is} generated in the tank (1). Achieving level II is the beginning of the development of the tank (5), and from that moment only fuel is produced from the tank (5). The flowmeter reading is fixed at this moment, after which the flowmeter reading is monitored until it increases by Q ₅ . When this value of the flowmeter readings is reached, a signal is generated that the specified fuel balance has been reached in the PTB (5). The appearance of this signal is displayed by means of indication so that the pilot can make the necessary decision. Despite the appearance of a signal about the achievement of a given balance, the development of the tank continues (5).

Additionally, at the moment of starting the production of the tank (5), the readings of the sensors (14) of the fuel meter of the tank (1) are recorded, during the development of the PTB (5) they are monitored so that the readings of the sensor of the fuel meter (14) of the tank (1) are in a certain range. If they go beyond this range until a signal appears that the tank (5) is empty, they conclude that there is a failure in the process of developing the tank (5).

3. After developing the tank (5), the amount of fuel ΔQ _{2 is} generated from the tank (1). At this point, the development of the tank begins (6). The flowmeter reading is fixed at this moment and the flowmeter reading is monitored until it increases by Q ₆ . When this value of the flowmeter readings is reached, a signal is generated about the achievement of the specified fuel balance in the PTB (6) and its appearance is displayed by means of indication. Continue to develop the tank (6).

4. Next, the tank (1) and the tank (3) are fully developed.

Example 2: Implementation of the determination of the achievement of a given fuel balance in the PTB (5) in the case of the same fuel system. The main event for the PTB (5) is the end of the development of the tank (4).

For the purpose of removing restrictions on flight modes, it is permissible to take the moment of passage of the signal "tank (4) is empty" as a basic event. Then the amount of fuel that must be consumed (i.e., pass through the flowmeter sensor (15)) before reaching the specified fuel balance in the PTB (5) is equal to Q ₅ (calculated as the difference between the initial fuel supply in the PTB (5) and the specified the remaining fuel in the PTB (5)) plus the reserve in the tank (1) between levels I and II (ΔQ ₁ ).

Then perform the following steps:

- when the basic signal "tank (4) is empty" with the help of the calculator, the readings of the flowmeter P ₀ are recorded, and then the flowmeter is monitored until it increases by the amount (Q ₅ + ΔQ ₁ ),

- when this value of the flow meter readings is reached, they generate a signal about the achievement of the specified fuel balance in the PTB (5). The appearance of this signal is displayed by means of indication and the development of the tank (5) continues.

In the simplest case, the rate of flow from the tank (4) provides for the replenishment of the tank (1) at all engine operating modes at all stages of the flight profile. If it does not provide, then simultaneously with pumping from the tank (4) the fuel level in the tank (1) is lowered and upon reaching level II the “missing” fuel is added from the PTB (5), i.e. when will the development of fuel from the PTB (5). After emptying the tank (4) in the PTB (5) there will be less fuel. This error in determining the amount of fuel in the PTB (5) will continue to be continued, but in order to remove restrictions on the possibility of flying with the PTB, this is permissible for the following reasons:

- reducing the balance improves the condition for removing restrictions;

- The “error” by weight is negligible, since the operating time in the increased flow mode is small - several tens of seconds.

The base event for the development of the subsequent PTB (6) can be selected regardless of the choice of the base event for the PTB (5).

The polling frequency of the parameters is selected depending on the amount of fuel consumption per engine g and the amount of fuel ΔQ ₂ generated from the tank (1) from the moment the PTB is developed (5) to the moment the next tank starts to be developed, but has no decisive solution.

Thus, the foregoing shows that the receipt of a signal about the achievement of a given fuel balance in an outboard fuel tank during its generation can be realized by means available on board the aircraft. The task is to find an algorithm for issuing a signal on reaching a specified balance in the PTB - determining the reference point (base event), determining the costs from internal tanks and PTBs, constantly monitoring the fuel supply and comparing it with subsequent readings. There is no need to introduce additional sensors and assemblies into the system, the problem can be solved by introducing a new program in the computer calculator.

Claims (7)

1. The method of determining the achievement of a given fuel residue in an outboard fuel tank in the process of its generation, in which the base event is preliminarily determined and the amount of fuel that must be consumed after the basic event before reaching the predetermined remaining fuel in the outboard fuel tank is calculated; the flow meter reading and then monitor the flow meter readings until the value exceeds the recorded reading by the mentioned amount of fuel is reached And this value generates a signal about the achievement of a given fuel balance in the outboard fuel tank. 2. The method according to claim 1, characterized in that as the base event, the start of production of the said outboard fuel tank is selected. 3. The method according to claim 2, characterized in that devices are used that transfer fuel from the outboard fuel tank to the inner tank while maintaining the fuel level in the inner tank in a certain range, additionally, at the moment of starting the production of the outboard fuel tank, the fuel gauge of the inner tank is recorded, in the process of developing an outboard fuel tank, it is monitored so that the fuel gauge readings are in this specific range. 4. The method according to claim 1, characterized in that as the base event, the end of the fuel tank production is selected, which is generated immediately before the said outboard fuel tank. 5. The method according to any one of claims 1 to 4, characterized in that the determination of the fact of the onset of the base event, the recording and tracking of the flow meter, the formation of the said signal is carried out using a calculator. 6. The method according to any one of claims 1 to 4, characterized in that said signal is reflected by means of indication. 7. The method according to claim 5, characterized in that the fact of the formation of said signal is reflected by means of indication.

Images