RU2312242C2 - Method to control reactive thrust of turbojet engine - Google Patents

Abstract

FIELD: aircraft industry; turbojet engines.

SUBSTANCE: proposed method to control reactive thrust of turbojet engine comes to measuring the following parameters on bench: engine thrust R₀, pressure R₀, temperature T₀ and relative humidity B of air, determining partial pressure T₀ of water vapors basing of temperature P_W and relative humidity B of air, and reducing measured thrust R₀ to standard atmospheric pressure by formula R_red=R₀·760/P₀, with additional of correction R_red to thus found thrust ΔR=0,378 P_W/P₀·R_red.

EFFECT: provision of stable thrust performance for any engine of this type irrespective of atmospheric condition at bench tests.

Description

The invention relates to the field of aircraft engine manufacturing, in particular to turbojet engines (turbojet engines).

Known methods for controlling the thrust of a turbojet engine in high-altitude conditions by measuring at the thrust stand R ₀ , pressure P ₀ and temperature T _{0 of the} air at the engine inlet (see, for example, E.L. Solokhin. Tests of aircraft jet engines, M., Engineering, 1975, p. 272).

In the known method there is a significant dispersion of traction characteristics of various instances of engines of the same type in high-altitude conditions, depending on the atmospheric conditions under which the test was conducted on the bench, which is unacceptable. These circumstances are explained by the influence of water vapor contained in the air on engine thrust, which leads to the release from the engine stands of engines with higher flight thrust in the summer and less thrust in the winter (subject to the same bench debugging). A quantitative assessment shows that thrust scatter can reach 2-3% when the engine is running in a humid climate and high ambient temperature.

The effect of air humidity on engine thrust is realized by replacing part of the air with water vapor, which causes a decrease in the density of moist air compared to dry air and, as a result, reduces the jet thrust of the turbojet engine, which is proportional to the mass flow of air through the engine.

The indicated drawback can be eliminated by drying the air supplied to the engine (see, for example, E.L. Solokhin. Tests of aircraft jet engines, M., Mashinostroenie, 1975, p. 127, 147), however, due to the significant complication of the test Dehumidifiers are installed on unique stands only, and standard factory stands are not equipped with them.

A known method of controlling jet thrust turbofan engines with afterburner according to patent RU 2220305, IPC F02C 9/28, 12/27/2003, according to which the thrust R ₀ , pressure P ₀ , temperature T ₀ and relative humidity In air, temperature T ₀ and relative air humidity B determine the partial pressure of water vapor P _in and the obtained value of the partial pressure of water vapor P _{in is} used to clarify the coefficient of excess air in the afterburner.

The task to which the invention is directed is to maintain stable characteristics of the turbojet engine in high-altitude conditions regardless of the atmospheric conditions under which the engine was tested at the factory bench.

а для определения величины тяги турбореактивного двигателя в высотных условиях к величине приведенной тяги R_пр добавляют поправку, пропорциональную парциальному давлению паров воды в воздухе, причем поправку определяют по формуле

The problem is solved due to the fact that in the method of controlling the jet thrust of a turbojet engine in flight by measuring on the engine thrust stand R ₀ , pressure P ₀ , temperature T ₀ and relative humidity B of the air, determine by T ₀ and relative humidity B of the partial pressure water vapor P _in lead measured thrust R ₀ to standard atmospheric pressure according to the formula

and to determine the thrust of a turbojet engine in high-altitude conditions, a correction proportional to the partial pressure of water vapor in the air is added to the magnitude of the reduced thrust R _pr , and the correction is determined by the formula

When implementing the invention, all instances of a turbofan engine of this type, regardless of the atmospheric conditions under which the bench tests were carried out, will provide the same traction characteristics in high-altitude conditions, where due to the low temperature of the air environment (and therefore, the extremely low content of water vapor in the air), the influence of humidity air is negligible.

Consider an example of the implementation of the proposed method in relation to a hypothetical turbojet engine.

At the stage of bench testing:

1. measure the air pressure P ₀ = 740 mm Hg;

2. measure the air temperature T ₀ = 313K (40 ° C);

3. measure the jet thrust of the engine R ₀ = 5000 kg;

4. measure the relative humidity of the air B = 80%, which at T ₀ = 313 K corresponds to the partial pressure of water vapor P _in = 38.4 mm Hg

- determine the reduced thrust

- determine the correction to the draft

Therefore, in the conditions of "dry" air at a standard pressure of 760 mm Hg the traction motor provides instance R = R _pr + ΔR = 5235,7 kg, i.e. ~ 2% higher than under test conditions. This value should be taken as the base for calculating the thrust of a given engine instance in high-altitude conditions. With humidity B = 100%, the correction value can reach 2.5% of the measured thrust.

Using the proposed method for controlling jet thrust of a turbojet engine will ensure the stability of traction characteristics for all instances of an engine of this type, regardless of the atmospheric conditions for bench testing. In this case, special equipment is not required to dry the air entering the engine.

Claims (1)

A method for controlling jet thrust turbojet engine in flight by measuring at the stand thruster R ₀ and pressure P ₀ and temperature _T0 and relative humidity in the air, determining the temperature T ₀ and a relative humidity in the partial pressure of water vapor P _in, wherein which lead the measured draft R ₀ to standard atmospheric pressure according to the formula

and to determine the thrust of a turbojet engine in high-altitude conditions, a correction proportional to the partial pressure of water vapor in the air is added to the magnitude of the reduced thrust R _pr , and the correction is determined by the formula