RU2467360C1 - Method of forming model for predicting formation of condensation trails of aircraft with specific type of gas-turbine engine using quantitative indicators for formation of condensation trails and possibility of reducing impact of engine emission on greenhouse effect - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to aviation and ecology and can be used to detect conditions of adverse effect of aircraft engine emission on climate change and developing methods of abating that effect. The following is measured on cruise flights at different altitudes: pressure p, outside air temperature t_oa°C (T_oa°K), relative humidity (φ_oa, %) of atmospheric air, flight speed (number M), full gas temperature behind the low-pressure turbine

rotor frequency n (engine operating mode), fuel consumption G_F. Using these data and design characteristics of a specific engine, the full gas temperature behind the mixing chamber

is calculated, the average temperature of the mixed jet T_{mix av} is calculated, the curve h_Σ=f(H) is plotted and from the condition h_Σgr.calc.=0 the limiting height of formation of the condensation trace H_{0 gr.msd} in standard atmospheric conditions is determined; the total humidity over-saturation indicator h_Σexp. is then calculated for each specific experiment based on the measured parameters in flight taking into account the specific type of the engine; the limiting value the total vapour over-saturation indicator h_Σgr.exp. is calculated for the specific type of the engine; the values h_Σgr.calc. and h_Σgr.exp. are compared. If h_Σgr.calc. and h_Σgr.exp. are different, T_{mix av} is refined based on characteristic features of the specific aircraft with a specific type of engine.

EFFECT: technical result from using the disclosed invention is the possibility of more reliable and more accurate determination of the limiting height of formation of persistent condensation trails for aircraft with a specific type, design and arrangement of gas-turbine engines, which enables to give recommendations for the type of aircraft under investigation to fly in a range of altitudes without forming persistent condensation trails, i.e., with minimum impact on the greenhouse effect.

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Description

The invention relates to the field of aviation and ecology and can be used to identify conditions for the adverse effect of aircraft engine emissions on climate change and to develop ways to reduce this effect.

Modern estimates of anthropogenic environmental impacts show that aviation makes a significant contribution to air pollution. The combustion products emitted by aircraft engines increase the concentration of carbon dioxide, water vapor, methane, nitrogen oxides, etc. and contain aerosols and particles, which in turn initiate the formation and development of cirrus clouds. As a result, all these factors increase the “greenhouse” effect of the atmosphere. In this context, the expected increase in air traffic may have a significant impact on the development, extent and frequency of cirrus cloud formation.

One of the most significant factors in the influence of aviation on the formation and development of cirrus clouds is the condensation trails (traces) of aircraft, which are formed as a result of condensation and freezing of water vapor contained in the exhaust jet of aircraft engines. Condleds are formed at the same heights as cirrus clouds, in structure they are close to them and they are even called artificial cirrus clouds (Cirrus tractus). According to estimates from the beginning of the 1990s, the area covered by the trail can be on average about 0.1% of the earth's surface, but varies greatly by region, and by 2050 it can be expected to increase to 0.5%. The expected increase will occur as a result of both an increase in air traffic and an increase in the efficiency of aircraft engines. But much more significant is that under appropriate meteorological conditions (increased humidity at low temperatures, usually below -40 ° C) in the upper layers of the troposphere and lower layers of the stratosphere, conduces can serve as a triggering mechanism (“trigger” effect) for formation and especially for intensive development of cirrus clouds existing near the route of the airway.

In order to reduce the level of pollution created by aviation (noise, emission of gaseous substances and aerosols), ICAO recommends promoting the introduction of, in addition to technical, additional means and methods (rules, restrictions) that contribute to reducing the harmful effects on the environment.

Tracks are formed with a certain combination of a number of factors: pressure p and atmospheric air temperature t _нв at the corresponding height Н, flight speed V _ucm , exhaust gas temperature behind the turbine Т _т and behind the mixing chamber (if any), excess air coefficient α _кс (α _cm ).

As is known, the process of formation of condleds is described by the currently accepted Schmidt-Appleman hypothesis (model) (see Review-articfle article by Schumann U., Meteorol. Zeitschrift, February, 1996), a graphical interpretation of which is shown in Fig. 1, where e _Нв - partial pressure of water vapor of atmospheric air Е _в , Е _л - values of the partial pressure of saturated steam above water and above ice, the dependences of е _нв , Е _в , Е _л on temperature are given. Physically, during the cooling process of the mixed exhaust stream, a CS begins to form when the temperature of the stream drops to the dew point (point t ^' in Fig. 1) and upon further cooling, vapor supersaturation occurs (above water), as a result of which condensate is released. This process continues until the humidity decreases due to further mixing of the jet with the surrounding air (dilution) to a value at which supersaturation stops despite a decrease in temperature (point t ^'' in Fig. 1). Subsequently, the trail continues to exist as long as the vapor pressure remains above the saturation pressure above the ice. When the vapor pressure drops below this value, the conductor rapidly evaporates.

The intensity of the formation of traces and their density (the so-called power) depends on the amount of supersaturation over water. In turn, the amount of supersaturation depends mainly on the temperature of the air and pressure (altitude). The angle of inclination of direct mixing also depends on the thermophysical characteristics of a particular type and design of the aircraft engine. Thus, it is practically possible to avoid the formation of stable traces by changing the flight altitude along the route. In the Impact of Cruise Altitude on Contrails, in the collection of publications of the conference “Proceedings of the AAC - Conference, June 30 to July 3, 2003, Fridrichshafen, Germany” by C. Fichter et al., Data are presented on the effect of changes in flight altitude on conductor formation and, accordingly, the thermal balance of the atmosphere in different seasons and on average per year. Thus, a decrease in altitude of 6,000 feet (1,800 m) relative to some base value leads to a decrease in the formation of condoms to 80% in July, to 20% in January and about 40% on average per year; an increase in altitude of 2,000 feet (600 m) increases conductor formation by ~ 25% in July, has little effect in January, and increases by a few percent on average per year. From these data it follows that a change in the level of the echelon can significantly affect the formation of condleds. A method for determining the boundary height of the formation of condoms H _0gr. not specified in the work.

(тангенс угла наклона прямой смешения), рассчитываемый по полной температуре, получается существенно заниженным по сравнению с газодинамическим расчетом (прямая 1 на фиг.2). В то же время расчет, выполненный для статической температуры струи, дает существенно завышенное значение градиента (прямая 2 на фиг.2). Практически вполне приемлемая точность получается при расчете градиента для некоторой осредненной температуры смешанной струи Т_см.ср. между

и Т_см (прямая 3) - как видно из фигуры, прямая 3 проходит между прямыми 4, полученными для указанного выше точного численного расчета (две прямые 4 получены параметрически для вариации расчетной длины начального участка смешанной струи на 3 калибра сопла в ту и другую стороны).However, the Schmidt-Appleman model and subsequent modifications to this model assume a uniform mixing of the exhaust stream with atmospheric air. In this case, the total (inhibited) jet temperature T ^{* is} taken in the calculations. To verify the validity of the described model, the authors of the application performed a detailed numerical gas-dynamic calculation of the process of mixing the exhaust jet with the atmosphere based on the solution of the complete system of equations of gas dynamics taking into account turbulent mixing. The calculation results show that the gradient of change in humidity of the mixed jet

(the tangent of the slope of the direct mixing), calculated at full temperature, is significantly underestimated in comparison with the gas-dynamic calculation (line 1 in figure 2). At the same time, the calculation performed for the static temperature of the jet gives a significantly overestimated value of the gradient (line 2 in FIG. 2). A practically acceptable accuracy is obtained when calculating the gradient for a certain averaged temperature of the mixed jet T _cm.s. between

and T _cm (straight line 3) - as can be seen from the figure, straight line 3 passes between straight lines 4 obtained for the above exact numerical calculation (two straight lines 4 are obtained parametrically to vary the estimated length of the initial section of the mixed jet by 3 nozzle calibers on either side) )

Closest to the proposed method is the method contained in patent No. 2312379 of January 11, 2006, "A method for predicting the quantitative indicators of condensation traces emitted by aircraft engines, to assess their compliance with an environmentally acceptable level of emissions", in which the height H is measured in a cruise flight, pressure P, t _outdoor temperature, the partial pressure of water vapor outside _HB e, gas temperature after the turbine t _T and the rotational speed of the engine type under test, calculating the temperature grad ent moisture mixed exhaust jet B ₀ (slope of a straight line blending). The disadvantage of this method is that when calculating the parameters that determine the conditions for the formation of traces: temperature gradient of humidity B ₀ , steam supersaturation index h _m , temperature t _m , etc. the temperature of the mixed jet is taken as for a one-dimensional mixing process, which, as shown above, can lead to an underestimated value of the total supersaturation index h _∑ , in addition, the effect of deviations of the temperature of the atmosphere from the ISA and the engine operation parameters on the temperature of the mixed jet is not taken into account, i.e. ultimately, by the value of the boundary height of formation of a stable conductor H _0gr. .

The expected technical result from the use of the present invention is the possibility of a more reliable and more accurate determination of the boundary height of formation of stable conductors for an aircraft with a specific type, design, and location scheme of gas turbine engines on an aircraft, which will make it possible to give recommendations for the type of aircraft under consideration to operate flights in the altitude range without the formation of sustainable trace, i.e. with minimal impact on the formation of the greenhouse effect.

частоты вращения ротора n - режима работы двигателя, расхода топлива G_T, фиксации наличия или отсутствия образования конденсационных следов (КС), вычисление полной температуры газа за камерой смешения

, вычисление температурного градиента влажности смешанной струи газа и атмосферы В_0ср. - тангенса угла наклона «прямой смешения», вычисление парциального давления водяного пара в атмосфере h_нв, Па, вычисление показателя пересыщения влажности при смешении струи газа с «сухой» атмосферой h_м, вычисление количественного показателя суммарного пересыщения пара h_∑=h_м+h_нв, дополнительно вычисляют среднюю температуру смешанной струи Т_см.ср. по результатам расчета с использованием математической модели полей течения при двухмерном смешении струи газа и атмосферы с учетом обтекания мотогондолы двигателя и изменения скорости смешанного потока по длине смешения с дальнейшим осреднением значений Т_см.ср. и φ_нв по сечениям вдоль смешиваемой струи и построением «прямой смешения» струи газа и атмосферы, аналогичной «прямой смешения» при равномерном смешении для турбореактивного двухконтурного двигателя (ТРДД) с камерой смешения по формулеTo achieve the expected technical result in the method of generating a forecast model for the formation of condensation traces (CS) of aircraft with a specific type of gas turbine engine using quantitative indicators for the formation of CS and the possibility of reducing the effect of engine emissions on the greenhouse effect, including the measurement in cruising flight of an aircraft with a specific type of gas turbine engine (GTE) parameters: altitude H, pressure p, outdoor temperature t _nv ° C (T _nv K), relative humidity φ _nv ,% atmosp air, speed (number M) of flight, full gas temperature behind the low pressure turbine

rotor speed n - engine operating mode, fuel consumption G _T , fixing the presence or absence of the formation of condensation traces (CS), calculating the total gas temperature behind the mixing chamber

, calculation of the temperature gradient of humidity of a mixed stream of gas and atmosphere B _0av. - the slope of the slope of the “direct mixing”, the calculation of the partial pressure of water vapor in the atmosphere h _nv , Pa, the calculation of the moisture supersaturation index when mixing the gas stream with the “dry” atmosphere h _m , the calculation of the quantitative indicator of the total vapor supersaturation h _∑ = h _m + h _HB , additionally calculate the average temperature of the mixed jet T _{see cm.} according to the calculation results using a mathematical model of the flow fields during two-dimensional mixing of a gas jet and atmosphere, taking into account the flow around the engine nacelle and the change in the velocity of the mixed stream along the mixing length with further averaging of the values of T _cm.s. and φ _nv over the sections along the mixed jet and the construction of a “direct mixing” of a gas and atmosphere jet, similar to “direct mixing” for uniform mixing for a turbojet bypass engine with a mixing chamber according to the formula

- статическая температура газа за камерой смешения двигателя.

- static gas temperature behind the engine mixing chamber.

Calculate the temperature gradient of humidity in the mixed stream B _0av. for given values of the height and speed of the aircraft, taking into account the characteristics of a particular type of engine according to the formula

M _n is the relative mass of vapor emission equal to 0.084 kg / kg, p and T _nv are the pressure and temperature corresponding to the international standard atmosphere (ISA) at the calculated height N, α _cm - the excess air coefficient behind the mixing chamber is set based on the calculated characteristics of the engine.

Calculate the temperature t _m.cp. corresponding to the maximum supersaturation of the vapor in the mixed stream according to the formula

For each given height, the total quantitative indicator of steam supersaturation is calculated by the formula

- парциальное давление пара при температуре t_нв; φ_{нврасч.} - относительная влажность атмосферного воздуха, равная 60%, которая соответствует насыщению надо льдом, что является условием образования устойчивых КС.E (t _m.s. ) - the partial pressure of saturated steam at a temperature t _m.s. ;

- partial vapor pressure at a temperature t _nv; φ _nvrasch. - relative humidity of atmospheric air equal to 60%, which corresponds to saturation above ice, which is a condition for the formation of stable CS.

Based on the calculated values of h _∑ for the corresponding given heights of H at T _nv = T _{nvMSA, a} graphical dependence h _∑ = f (H) is constructed, then the value of the boundary height of the formation of KS H _{0g.MSA is calculated} , which is determined from the condition h _{∑ load calculation.} = 0. Then calculate the indicator of the total supersaturation of moisture h _спexp. For each specific experiment, taking into account the measured parameters in flight, according to formulas 1-4, taking into account the specific type of engine, the boundary value of the total supersaturation index h _∑гр.exp. for a particular type of engine in magnitude h _спexp. calculated in the presence and absence of a CS. Compare the values of the indicators h _∑gr.calc. and h _{∑group exp.} : with difference h _∑gr.exp. by h _Σgr.rasch. = 0 clarify the calculation of T _cm. taking into account the characteristics of a particular aircraft with a specific engine type.

For turbofan engines without a mixing chamber:

- the average temperature of the mixed jet T _cm.s. calculated by the formula

m - the bypass ratio of the engine is set based on the design characteristics of the engine;

temperature gradient of humidity in a mixed stream B _0av. for given values of the height and speed of the aircraft, taking into account the characteristics of a particular type of engine, is calculated by the formula

- α _HP - the coefficient of excess air at the outlet of the low pressure turbine is set based on the design characteristics of the engine;

- the indicator of the total supersaturation of humidity h _спexp. for each specific experiment, taking into account the measured parameters in flight, it is calculated by the formulas 5, 6, 3, 4.

Thus, it is possible to more reliably and more accurately determine the boundary height of formation of stable condoms for an aircraft with a specific type, design, and layout of gas turbine engines and identify the adverse effects of aircraft engine emissions on climate change and develop ways to reduce this effect.

The proposed method is illustrated by drawings:

figure 1 shows direct mixing during cooling of the exhaust stream in the atmosphere;

figure 2 shows the state of the jet in the coordinates "temperature - partial pressure";

figure 3 is an indicator of the supersaturation of the vapor of the mixed stream;

figure 4 - presents the results of the experiment to determine the boundary value of the index of total supersaturation of steam;

figure 5 - shows the boundary of the formation of stable CS.

The method is as follows.

частоту вращения ротора n (режим работы двигателя), расход топлива G_T. С использованием этих данных по расчетным характеристикам конкретного двигателя определяют полную температуру газа за камерой смешения

, вычисляют среднюю температуру смешанной струи T_см.ср.. Способы вычисления средней температуры струи несколько различаются для ТРДД с камерой и без камеры смешения:In cruising flights at various altitudes, pressure p, outdoor temperature t _nv ° C (T _nv K), relative humidity φ _nv ,% of atmospheric air, flight speed (number M), total gas temperature behind the low-pressure turbine are measured

rotor speed n (engine operation mode), fuel consumption G _T. Using these data, the total gas temperature behind the mixing chamber is determined from the design characteristics of a particular engine

, calculate the average temperature of the mixed jet T _{cm cf.} . The methods for calculating the average temperature of the jet are somewhat different for turbofan engines with and without a mixing chamber:

- for a turbojet bypass engine (turbofan engine) with a chamber for mixing internal and external circuits according to the formula

- статическая температура газа за камерой смешения двигателя;

- static gas temperature behind the engine mixing chamber;

- for turbofan engines without mixing chamber

m - the _{bypass ratio of the} engine is set based on the calculated characteristics of the engine, calculate the temperature gradient of humidity of the mixed gas stream and the atmosphere B _{0 av.}

- for turbofan engines with a mixing chamber according to the formula

- for turbofan engines without mixing chamber according to the formula

M _n is the relative mass of steam, equal to 0.084 kg / kg for currently used aviation fuel, p and T _nv are the pressure and temperature corresponding to the international standard atmosphere (MCA) at the estimated height H, α _HPP is the coefficient of excess air at the turbine exit low pressure is set on the basis of the calculated characteristics of the engine, α _cm is the coefficient of excess air behind the mixing chamber is set on the basis of the calculated characteristics of the engine, the temperature t _m.s. corresponding to the maximum supersaturation of steam in a mixed stream (see figure 3) according to the formula

calculate for each given height the total indicator of steam supersaturation according to the formula

- парциальное давление водяного пара в атмосфере, φ_{нврасч.} - относительная влажность атмосферного воздуха, равная 60%, которая соответствует насыщению надо льдом, что является условием образования устойчивых кондследов, по рассчитанным значениям h_∑ для соответствующих заданных высот Н при температуре, соответствующей МСА, T_нв=Т_нвМСА, строят графическую зависимость h_∑=f(H) и из условия h_{∑гp.расч.}=0 определяют величину граничной высоты образования КС Н_0гр.МСА в условиях стандартной атмосферы, затем вычисляют показатель суммарного пересыщения влажности h_∑эксп., для каждого конкретного эксперимента с учетом замеренных параметров в полете по формулам 1-6 с учетом конкретного типа двигателя, определяют граничное значение показателя суммарного пересыщения пара h_{∑гр.эксп.} для конкретного типа двигателя, сравнивают величины показателей h_{∑гр.расч.} и h_{∑гp.эксп.}: при отличии h_{∑гр.эксп.} от h_{∑гр.расч.} выполняют уточнение Т_см.ср с учетом особенностей конкретного самолета с конкретным типом двигателя.E (t _m.s. ) - the partial pressure of saturated steam at a temperature of t _m.s. ,

- partial pressure of water vapor in the atmosphere, φ _nvrasch. - the relative humidity of atmospheric air, equal to 60%, which corresponds to saturation above ice, which is a condition for the formation of stable conductors, using the calculated values of h _∑ for the corresponding given heights H at a temperature corresponding to the ISA, T _nv = T _nvMSA , build a graphical dependence h _∑ = f (H) and from the condition h _∑гp.calc. = 0 determine the value of the boundary height of the formation of CS N _0g.MSA in a standard atmosphere, then calculate the index of total moisture supersaturation h _спexp. , for each specific experiment, taking into account the measured parameters in flight according to formulas 1-6, taking into account the specific type of engine, determine the boundary value of the indicator of the total supersaturation of steam h _{∑group.exp.} for a specific type of engine, compare the values of the indicators h _∑gr.calc. and h _∑gr.exp. : with difference h _∑gr.exp. by h _{Σgr.rasch. Refine} T _cm.sr taking into account the characteristics of a particular aircraft with a specific engine type.

Example

The total supersaturation indicator is predicted, which characterizes the conditions for the formation of condensation traces when flying at altitudes of 8 ... 13 km to estimate the boundary height of the formation of the spacecraft.

смешанной струи на срезе сопла двигателя.At the indicated heights, measurements were made of pressure (P) and temperature (t _nv ) of atmospheric air, gas temperature behind the turbine (t _T ), engine speed (revolutions), fuel consumption, partial vapor pressure in ambient air (e _nv ). Based on these data and the calculated characteristics of this type of engine, the coefficient of excess air (α _cm ) and the total temperature are determined

mixed jet at the nozzle exit of the engine.

The data obtained are shown in table 1.

Table 1 H, km 8,717 10,176 12,644 9,690 10,161 11,352 The presence of the COP there is there is there is no no no R, kPa 32,051 25,725 17,345 27.71 25,787 21,399 t _nv , ° C -50.9 -56.0 -63.9 -48.2 -45.4 -46.9 e _nv , Pa 3.07 1,197 0.49 3.47 1.44 2,58 α _cm 19 18.7 12,4 22.66 18.5 11.9

, K

, K 390 387.4 466.2 366.5 398.1 491.9

We calculate the supersaturation index of the mixed jet h _∑

where the gradient of the partial vapor pressure in the mixed stream (the tangent of the angle of inclination of the mixing line) is calculated by the formula:

where M _n is the relative mass of steam equal to 0.084 kg / kg, E _B (t _m ) is the partial pressure of saturated steam above water at a temperature of t _m ; temperature t _m , corresponding to the maximum supersaturation of steam in a mixed stream, is determined by the formula

t _m = 9.142 lnB _{0 avg.} -45.57 ° C.

The dependence of E _B on temperature is available in the reference and specialized literature, and is also approximated with satisfactory accuracy by the Magnus formula

where a = 7.63 and b = 241.9; T _{see average} - the average temperature of the mixed jet is determined by the formula

- статическая температура газа за камерой смешения двигателя, вычисляют температурный градиент влажности в смешанной струе В_0ср. для заданных значений высоты и скорости.Where

- the static temperature of the gas behind the mixing chamber of the engine, calculate the temperature gradient of humidity in the mixed stream In _{0 av.} for given values of height and speed.

The calculation results are summarized in table 2 and are presented in figure 4.

table 2 H, km 8,717 10,176 12,644 9,690 10,161 11,352 T _{see average} , K 357 354.7 428.2 334.7 364.3 451.8 B _0cp. , Pa / K 1.66 1.33 0.848 1.48 1.35 1.06 t _M , ° C -41.9 -44 -48.3 -42.75 -44 -46.1 h _∑ , Pa 2 4.26 5.9 -2.63 -9.5 -6.45

According to the results of the experiment, presented in figure 4, determine the boundary value of the indicator of the total supersaturation of steam h _{∑gr.express.} . As can be seen from figure 4, h _∑gr.exp. ≈0, i.e. condensation traces are formed at h _∑gr.exp. > 0, for h _{∑group exp.} ≤0 - condensation traces are very weak or absent.

To determine the boundary height of the formation of CS, the calculation of the indicators of the total supersaturation of steam h _{∑ calc.} at altitudes of 9, 10, 11 km according to the design characteristics of this engine in a standard atmosphere according to the formulas 1 ... 3; the relative humidity for the calculations is taken to be 60%, which corresponds to the partial pressure of the vapor in the ambient air (e _nv ), equal saturation is necessary with ice at the appropriate temperature, which is the condition for the formation of stable CS.

The data obtained are shown in table 3 and figure 5.

Table 3 H, km R, kPa t _nv , ° C e _nv , Pa α _cm

, K

, K T _{see average} , K B _0cp. , Pa / K t _M , ° C h _{∑ calc.} , Pa 9 30.8 -43 7.8 12.8 472 435 1,52 -42.75 -5.64 10 26.5 -fifty 3.8 12.7 465 429 1.3 -44.2 -1.21 eleven 22.7 -56 1.8 12.7 459 424 1,1 -45.9 3.07

Calculate the value of the boundary height of the formation of KS N _0gr.MSA , which is determined from the condition h _∑gr.calc. = 0, which corresponds to the boundary of the formation of stable condensation traces. In this example, H _0g . _MSA ≈10.3 km.

Claims (1)

A method for generating a forecast model for the formation of condensation traces of aircraft with a specific type of gas turbine engine using quantitative indicators for the formation of condensation traces and the possibility of reducing the effect of engine emissions on the greenhouse effect, including measuring cruise flight of an aircraft with a specific type of gas turbine engine (GTE) of parameters: height H, pressure p, the outdoor temperature t ° C _HB (T _nv K) φ relative humidity _HB% air, the speed (Mach number) field and full gas temperature for the low-pressure turbine _LPT t ° C

, rotor speed n - engine operating mode, fuel consumption G _T , fixing the presence or absence of the formation of condensation traces (CS), calculating the total gas temperature behind the mixing chamber

, calculation of the temperature gradient of humidity of a mixed stream of gas and atmosphere В _0av - the slope of the direct mixing angle, calculation of the partial pressure of water vapor in the atmosphere h _нв , Pa, calculation of the supersaturation index when mixing the gas stream with a “dry” atmosphere h _M , calculation total score supersaturation h _Σ = h _M + h _HB, characterized in that the calculated average temperature of the mixed stream _sm.sr T to be calculated using a mathematical model of the flow fields when the two-dimensional cm shenii jet of gas and the atmosphere within the engine nacelle and the flow velocity of the mixed flow changes along the length of the mixing with a further averaging the values of T and φ _{sm.sr HB} loft along miscible jet and construction "direct mixing" of the gas jet and the atmosphere similar to the "direct mixing" with uniform mixing for a turbojet bypass engine (turbofan engine), depending on the presence or absence of a mixing chamber:
- with a mixing chamber according to the formula:

Where

- static gas temperature behind the engine mixing chamber;
- without mixing chamber according to the formula:

where m is the bypass ratio of the engine is set based on the design characteristics of the engine;
calculate the temperature gradient of humidity in the mixed stream B _{0 cp} for the given values of the height and speed of the aircraft, taking into account the characteristics of a particular type of engine depending on the presence or absence of a mixing chamber:
- with a mixing chamber according to the formula:

where M _n is the relative mass of vapor emission equal to 0.084 kg / kg, p and T _nv are the pressure and temperature corresponding to the international standard atmosphere (ISA) at the calculated height N, α _cm is the excess air coefficient behind the mixing chamber is set based on the calculated characteristics of the engine ;
- without mixing chamber according to the formula:

where α _tnd - the coefficient of excess air at the outlet of the low pressure turbine is set based on the design characteristics of the engine;
calculate the temperature t _cm.sr , corresponding to the maximum supersaturation of the vapor in the mixed stream according to the formula:

calculate for each given height the total quantitative indicator of steam supersaturation according to the formula:

where E (t _{cm cf} ) is the partial pressure of saturated steam at a temperature of t _{cm cf} ;

- partial vapor pressure at a temperature t _nv ; φ _nv.calc — the relative humidity of atmospheric air equal to 60%, which corresponds to saturation above ice, which is a condition for the formation of stable CS;
from the calculated values of h _∑ for the corresponding given heights H at T _nv = T _{nv.MSA, a} graphical dependence h _∑ = f (H) is built, then the value of the boundary height of the formation of CS N _{0 gr.MSA is calculated} , which is determined from the condition h _{∑ gr.} = 0, then the total calculated rate of supersaturation humidity h _Σeksp for each experiment with the parameters measured in flight by formulas 1-4 with the particular type of engine, determine limit value indicator total supersaturation h _Σgr.eksp for a particular type move in! ator largest h _Σeksp calculated with the existence and absence of the COP values are compared _Σgr.rasch parameters h and h _Σgr.eksp: the difference _Σgr.eksp h from h = 0 _Σgr.rasch clarify the calculation of T _sm.sr taking into account the characteristics of a particular aircraft with a specific engine type.

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