RU2041399C1 - Method and device for protecting turbo-compressor against pumpage - Google Patents

Abstract

FIELD: engine engineering. SUBSTANCE: air pressure downstream of the first group of compressor stages and gas pressure at the outlet of the propulsive nozzle are measured to form signals of pumpage existing when the rate of changing of the sum of pressure downstream of the first group of the compressor stages and the gas pressure at the outlet of the propulsive nozzle or rate of changing of the air pressure downstream of the compressor exceed threshold pressure. The signals, which are fed to fuel cut-off valves, are generated to eliminate deep pumpage when the rate of changing of the sum of the pressure of air downstream of the first stage of the compressor, gas pressure at the outlet of the nozzle and air pressure downstream of the compressor exceed threshold pressure simultaneously. The device additionally has an air pressure gauge downstream of the first group of the compressor stages and gas pressure gauge at the outlet of the propulsive nozzle, adder, and the second differentiator. EFFECT: enhanced reliability. 3 cl, 2 dwg

Description

 The invention relates to engine building and can be used in systems for protecting gas turbine engines from surging.

 A known method of protecting a turbocharger from surge and a device for its implementation. The method is carried out by measuring the air pressure behind the compressor and using as a first protection parameter, determining its rate of change, comparing with the threshold value and signal delay, measuring the second turbocompressor parameter, determining its speed of changing, comparing with the threshold value and generating a signal to the fuel cut-off valve in case of simultaneous receipt of signals corresponding to the first and second parameters of the turbocompressor. The known device comprises an air pressure sensor behind the compressor, connected through a first differentiator to a first threshold element, the first output of which is connected via a delay element to the first input of the element And connected to the fuel shut-off valve, to the second input of which the first output of the second threshold element is connected, the input of which is connected with the output of the second differentiator.

 The disadvantages of the method and device is the low reliability of surge recognition.

 The aim of the invention is to increase the reliability of recognition of surge.

 This is achieved by protecting the turbocharger from surge by measuring the air pressure behind the compressor and the air pressure behind the first group of compressor stages and applying a signal to the air bypass belt behind the compressor, which measures the gas pressure at the jet nozzle exit and generates surge signals if the threshold value is exceeded the rate of change of the sum of the air pressure values behind the first group of compressor stages and gas pressure, at the exit of the jet nozzle or in case of exceeding the threshold value the rate of change of the air pressure behind the compressor, and also generate signals to the fuel shutoff valve to eliminate deep surge if the threshold value is simultaneously exceeded by the rate of change of the sum of the air pressure values behind the first group of compressor stages and the gas pressure at the nozzle exit and the threshold is exceeded by speed changes in the delayed value of the air pressure behind the compressor.

 The goal is achieved by a device implementing the above method, comprising an air pressure sensor behind the first group of compressor stages and an adder connected in series with it, an air pressure sensor behind the compressor and a first threshold device into which a second differentiator and a second threshold device and circuit connected in series are connected And, the output of which is connected to the fuel cut-off valve, the gas pressure sensor at the jet nozzle exit, the output of which is connected to the second input of the adder, the output which is connected to the input of the second differentiator, the first differentiator, the output of which is connected to the input of the first threshold device, and the input to the output of the air pressure sensor behind the compressor, as well as the OR circuit and the delay element, the output of which is connected to the second input of the AND circuit, and the input to the output the first threshold device, and with the first input of the OR circuit, wherein the second input of the OR circuit is connected to the output of the second threshold device.

 In FIG. 1 and 2 show a structural diagram of a device implementing this method, and its graphs.

The device comprises an air pressure sensor 1 behind the first group of compressor stages P ₂ ^(I) , a gas pressure sensor 2 at a jet nozzle exit (p / s) P _s , an air pressure sensor 3 behind compressor P ₂ , an adder 4; first differentiator 5, second differentiator 6, first threshold device 7, second threshold device 8, OR circuit 9, delay element 10, AND circuit 11.

Moreover, the air pressure sensor behind the compressor P ₂ 3 is connected in series with the first differentiator 5, the first threshold device 7, the delay element 10 and the circuit And 11, the output of which is connected to the fuel cut-off valve. The air pressure sensor behind the first group of compressor stages P ₂ ^(I) 1 is connected in series with the adder 4, the second differentiator 6, the second threshold device 8 and the OR 9 circuit. The output of the gas pressure sensor at the jet nozzle exit P _with 2 is connected to the second input of the adder 4 The second output of the first threshold device 7 is connected with the second input of the OR circuit 9, and the output of the second threshold device 8 with the second input of the AND circuit 11.

 The method is as follows.

The adder 4 summarizes the values of the signals coming from the outputs of the air pressure sensor behind the first group of stages of the compressor and the gas pressure sensor at the exit of the jet nozzle P _with 2. Next, this signal enters the second differentiator 6, which differentiates its value. In the second threshold device 8, its threshold value is compared with the signal coming from the output of the second differentiator 6, when exceeded which signals are output to the OR circuits 9 and the I 11 circuit. At the same time, the first differentiator 5 differentiates the signal values coming from the output of the air pressure sensor behind the compressor R ₂ 3. The first threshold device 7 compares its threshold value to the signal output from the first differentiator 5, above which signals are sent to an OR gate 9 and lement delay 10, the output of which a signal is output to the AND circuit 11. If the input of the OR circuit 9 will be at least one signal, and its output signal is issued to the tape for the compressor bleed air to eliminate surge breakdown. If sines appear on both inputs of the And 11 circuit, then a signal is sent from its output to the fuel cut-off valve to eliminate deep surge.

The surge recognition effect consists in calculating and controlling the engine thrust (as the sum of the parameters Р ₂ ^(I) and Р _с ) and at the same time monitoring the “delayed” value of the signal Р ₂ , since the change in the latter is more significant than the other parameters. Moreover, the rate of change of P _{2 is} compared with the threshold, excluding the possibility of false alarms (possible small pressure fluctuations that always take place) about surge phenomena.

 One of the important parameters of an aircraft engine is its thrust R. It is obvious that when surging processes occur, the thrust R will significantly decrease, so it can be used as a stability criterion.

It is known that the thrust component R is the total flow momentum I _c = G _c C _c + G ₂ ^(I) C ₂ ^(I) , where C _c , C ₂ ^(I) are the flow velocities respectively at the jet nozzle exit and behind the first group compressor stages (this takes into account one of the most important conclusions that, in the process of the appearance and development of surge, the main role is played by the energy exchange between the groups of compressor stages); G _c , G _c ^{(I) the} mass flow rate of gas in the jet nozzle, the mass flow rate of air behind the first group of stages of the compressor.

S

·

G $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I)= Q $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I)ρ $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I)=S $\genfrac{}{}{0ex}{}{\text{I}}{\text{2}}$ C

S

·

где Q_c, ρ_c, S_c, P_c, T_c объемный расход газа, плотность, площадь сечения, давление и температура на срезе реактивного сопла соответственно;
Q₂ ^(I), ρ₂ ^(I), S₂ ^(I), P₂ ^(I), T₂ ^(I) то же, но для выхода из первой группы ступеней компрессора;
k и R₁ коэффициент адиабаты и газовая постоянная соответственно.After the conversion of mass costs
G _c = Q _c ρ _c = S _c C _c

S

·

G $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I) = Q $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I) ρ $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I) = S $\genfrac{}{}{0ex}{}{\text{I}}{\text{2}}$ C

S

·

where Q _c , ρ _c , S _c , P _c , T _c gas volumetric flow rate, density, cross-sectional area, pressure and temperature at the jet nozzle exit, respectively;
Q ₂ ^(I) , ρ ₂ ^(I) , S ₂ ^(I) , P ₂ ^(I) , T ₂ ^(I) the same, but to exit the first group of compressor stages;
k and R _{1 are} the adiabatic coefficients and the gas constant, respectively.

·

μ₁P_c;
C $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I)·S $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^II)

= μ₂P $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I);
μ₁= S

μ₂= S

.Thus, the momenta will be equal
C _c S _c

·

μ ₁ P _c ;
C $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I) S $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^II)

= μ ₂ P $\genfrac{}{}{0ex}{}{\text{(}}{\text{2}}$ ^I) ;
μ ₁ = S

μ ₂ = S

.

Therefore, the total momentum is
I _c = μ ₁ P _c + μ ₂ P ₂ ^(I)
Comparison of it and P ₂ with thresholds allows you to create an invention, i.e.

P ₂ ≥C _{por 1} ,
μ ₁ Р _s + μ ₂ Р ₂ ^(I) ≥ С _por.2 , where С _por.1 , С _por.2 predetermined threshold values. Moreover, the channel P _{2 is} introduced with a delay element, since it changes faster during surge than other parameters (see Fig. 2 a, b, c).

 Compared with the prototype, the method and device have a higher accuracy of surge recognition. The device does not require the creation of unique equipment; it can be performed on the basis of ordinary serial elements. An increase in the number of elements leads to a slight increase in the cost of the device. The economic effect of the invention is achieved by increasing the resources of the power plant.

Claims (2)

 1. A method of protecting a turbocharger from surge by measuring the air pressure behind the compressor and using it as a first protection parameter, determining its rate of change, comparing with a threshold value and signal delay, measuring a second turbocompressor parameter, determining its speed of change, comparing with a threshold value and generating the signal to the fuel shutoff valve in the case of simultaneous receipt of signals corresponding to the first and second parameters of the turbocharger, characterized in that, in order to increase reliability, measure the air pressure behind the first group of stages of the compressor and the gas pressure at the jet nozzle exit, summarize the measured signals, use the resulting amount as the second parameter of the turbocharger and generate a signal on the compressor bypass tape in the event of any signal corresponding to the first or second parameter of the turbocompressor .  2. Device for protecting the turbocharger from surge, containing an air pressure sensor behind the compressor, connected through the first differentiator to the first threshold element, the first output of which is connected through the delay element to the first input of the element And connected to the fuel shut-off valve, to the second input of which the first output of the second a threshold element, the input of which is connected to the output of the second differentiator, characterized in that, in order to increase reliability, it contains an air pressure sensor behind the first group of stupas a compressor, a gas pressure sensor at the jet nozzle exit, an adder and an OR element, the outputs of the pressure sensors being connected to the inputs of the adder, the output of which is connected to the input of the second differentiator, and the second outputs of the first and second threshold elements are connected to the inputs of the OR element associated with the tape compressor bypass.

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