RU2511814C1 - Method to determine temperature of gas upstream turbine in afterburning mode of turbojet engine - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: in the method for determination of gas temperature upstream a turbine in the afterburning mode of a turbojet engine they measure gas temperature at maximum and afterburning modes downstream the turbine T_4M and T_4F, they also measure at the maximum and afterburning modes the pressure downstream the compressor P_KM and P_KF and downstream the turbine P_TM and P_TF, further they determine gas temperature upstream the turbine at the maximum mode before start of afterburning of T_GM. Then a formula is given for determination of gas temperature upstream the turbine in the afterburning mode T_GF.

EFFECT: increased accuracy of gas temperature determination upstream a turbine in afterburning mode due to reduction of rated values and use of the method of indirect measurement.

Description

The invention relates to aviation and is intended to determine the temperature of the gas during testing and operation of gas turbine engines in afterburner modes.

A known method of determining the temperature of the gas in front of the turbine in afterburner mode through the heat balance equation:

(см. Ю.А. Литвинов, В.О. Боровик. Характеристики и эксплуатационные свойства авиационных турбореактивных двигателей. Изд. Москва, «Машиностроение» 1979 г., стр.155, формула 5.47). $$c_{R_{\mathrm{at}}}^{T^{\ast }{}_g}{T}^{\ast }{}_{{}_G}+q_T{n}^{T^{\ast }{}_g}{T}^{\ast }{}_{{}_G}=q_T\left(H_U{\eta }_G+n^{T_0}{T}_0\right)+c_{R_{\mathrm{at}}}^{T^{\ast }{}_{\mathrm{to}}}{T}^{\ast }{}_{{}_{\mathrm{TO}}}$$

(see Yu.A. Litvinov, VO Borovik. Characteristics and operational properties of aircraft turbojet engines. Moscow ed., "Mechanical Engineering" 1979, p. 155, formula 5.47).

The disadvantage of this method is the large number of calculated values, which in addition to the measurement error adds the calculation error.

The technical result, objectively achieved by using the claimed method, is to increase the accuracy of calculating the temperature of the gas in front of the turbine in the afterburner mode by reducing the calculated values and using the indirect measurement method, which makes it easier to determine the temperature in the afterburner mode.

The specified technical result is achieved by the fact that in the method for determining the gas temperature in front of the turbine in the afterburner mode of the turbojet engine, the gas temperature behind the turbine T _4M and T _4F is measured at maximum and afterburner modes, the pressure behind the compressor R _KM and R _{KF is} also measured at maximum and afterburner modes and after the turbine _TM P and P _TF further define the gas temperature before the turbine at maximum output before switching afterburner _GM T, is then determined the gas temperature before the turbine at afterburning T _GF form of e:

, где $$T_{GF}=T_{GM}+{\mathrm{to}}_{\mathrm{one}}\left(\left(T_{\mathrm{four}f}-T_{\mathrm{four}M}\right)+{\mathrm{to}}_2\left(\frac{R_{\mathrm{TO}F}}{R_{TF}}-\frac{R_{\mathrm{TO}M}}{R_{TM}}\right)\right)$$

where

to ₁ - coefficient taking into account the operation of the afterburner pump, determined by the formula:

to ₁ = ΔT _G / ΔT ₄ , where

ΔТ _Г - gas temperature difference in front of the turbine at maximum and afterburner modes;

ΔТ ₄ - gas temperature difference behind the low-pressure turbine at maximum and afterburner modes;

to ₂ - coefficient determined by the formula:

, где $${\mathrm{to}}_2=\frac{T_{\mathrm{four}F}-T_{\mathrm{four}M}}{{\pi }_{TF}-{\pi }_{TM}}$$

where

π _TF - the degree of expansion of gas on the turbine in the afterburner mode;

π _ТМ - gas expansion degree on the turbine at maximum mode;

Due to the fact that when calculating the temperature of the gas in front of the turbine in afterburner mode according to the above equation, the number of calculated values is minimized to one, the reliability of determining this temperature in comparison with the prototype increases.

The following is an example implementation of the inventive method for determining the gas temperature in front of the turbine in the afterburner mode of a turbojet engine:

At maximum engine operation, measure with receivers

full pressure, the pressure behind the compressor R _KM , kg / cm ² , the pressure behind the low-pressure turbine P _TM , kg / cm ² , and measure the temperature of the gas behind the turbine T _4M , K with thermocouples.

Next, we determine the temperature of the gas in front of the turbine at the maximum mode T _GM , K, by any known method, for example, through the heat balance equation:

$$T^{\ast }{}_G=\frac{q_T\left(H_U{\eta }_G+n^{T_0}{T}_0\right)+c_{R_{\mathrm{at}}}^{T^{\ast }{}_{\mathrm{to}}}{T}^{\ast }{}_{{}_{\mathrm{TO}}}-c_{R_{\mathrm{at}}}^{T^{\ast }{}_g}{T}^{\ast }{}_G}{q_T{n}^{T^{\ast }{}_g}}$$

Then the engine is displayed in the afterburner mode, which takes the same measurements P _KF , kg / cm ² , P _TF , kg / cm ² , T _4F , K.

Next, we calculate the coefficients k ₁ and k ₂ . These coefficients are determined for each engine type separately during special tests.

To determine the coefficient k _{1, we} determine the gas temperature at the maximum T _GM and forced T _GF engine operating modes (these temperatures are calculated through the heat balance equation). In the same modes, respectively, using thermocouples, we measure the gas temperature behind the low-pressure turbine T _4M and T _4F and calculate the coefficient k ₁ by the formula:

to ₁ = ΔT _G / ΔT ₄

To determine the coefficient k ₂ at maximum engine operation, the full pressure detectors measure the pressure in front of the turbine P _1TM , the pressure behind the low-pressure turbine P _TM and measure the temperature of the gas behind the low-pressure turbine T _{4M with} thermocouples. Next, we perform similar measurements in the forced mode of engine operation and measure P _1TF , P _TF and T _4F . We calculate by the formula the total degree of gas expansion on turbines at the maximum π _ТМ and forced π _ТФ modes:

$${\pi }_{TM}=\frac{R_{\mathrm{one}TM}}{R_{TM}}$$

Next, we calculate the coefficient k ₂ by the formula:

$${\mathrm{to}}_2=\frac{T_{\mathrm{four}F}-T_{\mathrm{four}M}}{{\pi }_{TF}-{\pi }_{TM}}$$

Then we calculate the temperature of the gas in front of the turbine in the afterburner mode of the turbojet engine T _GF , K, according to the formula:

$$T_{GF}=T_{GM}+{\mathrm{to}}_{\mathrm{one}}\left(\left(T_{\mathrm{four}f}-T_{\mathrm{four}M}\right)+{\mathrm{to}}_2\left(\frac{R_{\mathrm{TO}F}}{R_{TF}}-\frac{R_{\mathrm{TO}M}}{R_{TM}}\right)\right)$$

Claims (1)

The method of determining the gas temperature in front of the turbine in the afterburner mode of a turbojet engine, characterized in that the gas temperature behind the turbine T _4M and T _4F is measured at maximum and afterburner modes, the pressure behind the compressor R _KM and R _KF and behind the turbine is also measured at maximum and afterburner modes R _TM and R _TF , then determine the temperature of the gas in front of the turbine at maximum mode before turning on the afterburner T _GM , then determine the temperature of the gas in front of the turbine in the afterburner mode T _GF , according to the formula:
$$T_{GF}=T_{GM}+{\mathrm{to}}_{\mathrm{one}}\left(\left(T_{\mathrm{four}f}-T_{\mathrm{four}M}\right)+{\mathrm{to}}_2\left(\frac{R_{\mathrm{TO}F}}{R_{TF}}-\frac{R_{\mathrm{TO}M}}{R_{TM}}\right)\right)$$

where
to ₁ - coefficient taking into account the operation of the afterburner pump, determined by the formula:
to ₁ = ΔT _G / ΔT ₄ , where
ΔТ _Г - gas temperature difference in front of the turbine at maximum and afterburner modes;
ΔТ ₄ - gas temperature difference behind the low-pressure turbine at maximum and afterburner modes;
to ₂ - coefficient determined by the formula:
$${\mathrm{to}}_2=\frac{T_{\mathrm{four}F}-T_{\mathrm{four}M}}{{\pi }_{TF}-{\pi }_{TM}}$$

where
π _TF - the degree of expansion of gas on the turbine in the afterburner mode;
π _ТМ - the degree of gas expansion on the turbine at maximum mode.