CN110929341A - Helicopter tail propeller pitch range design method - Google Patents
Helicopter tail propeller pitch range design method Download PDFInfo
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- CN110929341A CN110929341A CN201911227694.1A CN201911227694A CN110929341A CN 110929341 A CN110929341 A CN 110929341A CN 201911227694 A CN201911227694 A CN 201911227694A CN 110929341 A CN110929341 A CN 110929341A
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Abstract
The invention belongs to the field of helicopter flight mechanics design, and provides a helicopter tail pitch range design method based on atmospheric density change, which comprises the steps of determining an initial maximum tail pitch; determining a maximum torque limit; calculating the tail rotor torque at a given atmospheric density: calculating to obtain tail rotor torques of different tail rotor pitches under the given atmospheric density according to the given atmospheric density and the tail rotor torques corresponding to the different tail rotor pitches; calculating the maximum tail pitch under the given atmospheric density; determining the actual maximum tail pitch Pedal: determining the maximum tail pitch corresponding to the stalling angle of the tail rotor as Pedal3Maximum tail pitch of structural constraint is Pedal4Transient limiting torque Q in standard atmospheric and sea level conditionsTransient stateThe corresponding maximum tail pitch is Pedal5And maximum tail rotor for the given atmospheric density ρDistance Pedal2Selecting Pedal2、Pedal3、Pedal4、Pedal5The minimum value in (1) is the actual maximum tail pitch, padal.
Description
Technical Field
The invention belongs to the field of helicopter flight mechanics design, and particularly relates to a helicopter tail pitch range design method.
Background
The main function of the helicopter tail pitch is to balance the reaction torque, while the maximum tail pitch affects the side wind resistance of the helicopter. Because of the limitation of torque, a fixed tail rotor pitch range is generally adopted, but with the increase of the flight height of the helicopter and the consideration of the high-temperature condition, the atmospheric density is reduced to some extent, so that the tail rotor capability is reduced, the crosswind resistance of the helicopter is reduced, and the high-temperature and plateau use of the helicopter is influenced. The existing tail pitch is fixed, and the side wind resistance in a plateau environment is weak.
Disclosure of Invention
The purpose of the invention is as follows: under the conditions that the original structure of the tail rotor is not changed basically and the weight is not increased, the maximum tail rotor pitch of the helicopter under the conditions of high temperature and altitude is increased, and the high-temperature and altitude crosswind resistance of the helicopter is further improved.
The technical scheme of the invention is as follows: a helicopter tail pitch range design method based on atmospheric density change comprises the following steps,
determining the initial maximum tail pitch: obtaining a tail pitch range according to the balance reactive torque requirement and the crosswind resistance requirement of the helicopter, and determining the preliminary maximum tail pitch Pedal1；
Determining a maximum torque limit: obtaining tail rotor torque Q corresponding to different tail rotor pitches under standard atmospheric and sea level states according to the obtained tail rotor pitch range0And determining the maximum torque limit qmax; the maximum torque limit QmaxIncluding steady state torque limit QSteady stateAnd transient torque limit QTransient state；
Calculating the tail rotor torque at a given atmospheric density: according to the given atmospheric density rho and the tail rotor torque Q corresponding to the different tail rotor pitches0Calculating the tail of different tail propeller pitches under the given atmospheric densityA paddle torque Q;
calculating the maximum tail pitch for a given atmospheric density: limiting Q according to the steady state torqueSteady stateAnd calculating the maximum tail rotor pitch Pedal under the condition of the given atmospheric density rho2；
Determining the actual maximum tail pitch Pedal: determining the maximum tail pitch corresponding to the stalling angle of the tail rotor as Pedal3Maximum tail pitch of structural constraint is Pedal4Transient limiting torque Q in standard atmospheric and sea level conditionsTransient stateThe corresponding maximum tail pitch is Pedal5And maximum tail rotor pitch Pedal for said given atmospheric density ρ2Selecting Pedal2、Pedal3、Pedal4、Pedal5The minimum value in (1) is the actual maximum tail pitch, padal.
Further, the formula for calculating the tail rotor torque at a given atmospheric density is,
q is tail rotor torque under a given atmospheric density state, and the unit is N.m;
Q0the tail rotor torque corresponding to different tail rotor pitches under the standard atmospheric and sea level states has the unit of N.m;
rho-given atmospheric density, kg/m3
ρ0Atmospheric density at standard atmospheric, sea level, 1.225kg/m3；
K-a correction factor that takes into account the effect of Mach number, which can be typically taken as 1, or corrected by experimentation.
Further, the steady state torque limit is the maximum torque that the helicopter is allowed to use during normal flight, and the transient limit torque is the maximum torque that the helicopter is not allowed to use intentionally by the pilot during flight but is allowed to reach for a short time due to external environmental influences.
Further, the maximum tail rotor pitch Pedal2Not exceeding at the lowest temperature and the highestTransient torque limit Q allowed by helicopter in air pressure environmentTransient stateCorresponding tail rotor pitch.
Further, the maximum tail rotor pitch Pedal2The stall angle of attack of the tail rotor is not exceeded.
Further, according to the obtained tail propeller pitch range, tail propeller torques Q corresponding to different tail propeller pitches under standard atmospheric and sea level states are obtained through a tail propeller platform test0。
Further, according to said preliminary maximum tail pitch Pedal1Determining the maximum torque limit Q by tail rotor rig testingmax。
Furthermore, the tail rotor torque Q corresponding to different tail rotor pitches under the standard atmospheric and sea level states0Determining the limiting torque Q in the transient stateTransient stateLower maximum tail pitch Pedal5。
The invention has the beneficial effects that: the helicopter tail pitch range design method improves the application range of the actual maximum tail pitch of the helicopter in the high-temperature and plateau environment under the conditions of not changing the original structure of the tail pitch and not increasing the weight, thereby improving the high-temperature and plateau crosswind resistance of the helicopter.
Drawings
FIG. 1 is a schematic diagram of the design result of the tail pitch range of the helicopter of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The method for designing the tail pitch range of the helicopter according to the present invention will be described in further detail with reference to fig. 1.
The method for designing the tail pitch range of the helicopter provided by the embodiment comprises the following steps:
1) root of Chinese scholar treeDetermining the range of the tail rotor pitch according to the balance reactive torque requirement and the crosswind resistance requirement of the helicopter, and mainly and preliminarily determining the maximum tail rotor pitch Pedal1。
2) Obtaining tail rotor torque Q corresponding to different tail rotor pitches under the standard atmospheric and sea level states according to the determined tail rotor pitch range0And determining a maximum torque limit Qmax. The maximum torque limit should take into account the lowest temperature environment that the helicopter is allowed to use. The maximum torque limit includes a steady-state limit, which is the maximum torque that the helicopter is allowed to use during normal flight, and a transient limit, which is the maximum torque that the pilot is not allowed to use intentionally during flight but is allowed to reach for a short time due to external environmental influences and the like. If the steady-state limiting torque is QSteady stateTransient limiting torque of QTransient state。
According to the obtained range of the tail propeller pitch, tail propeller torques Q corresponding to different tail propeller pitches under standard atmospheric and sea level states are obtained through a tail propeller platform test0. According to the preliminary maximum tail pitch Pedal1Determining the maximum torque limit Q by tail rotor rig testingmax。
3) Calculating the torque of the tail rotor at a given atmospheric density,
first, the atmospheric density under given atmospheric conditions is calculated.
The atmospheric density of standard atmosphere and sea level is 1.225kg/m3The atmospheric density under non-standard atmospheric conditions is calculated from the atmospheric pressure and atmospheric temperature:
Δ＝(1-0.0065×Hp/288.15)5.25588(1)
ρ＝σ×ρ0(4)
wherein Δ -pressure ratio;
theta-temperature ratio;
sigma-density ratio;
hp-pressure height, m;
th-atmospheric temperature, ° C;
rho-atmospheric density in kg/m under given conditions3；
ρ0Atmospheric density at standard atmospheric, sea level, 1.225kg/m3；
Secondly, according to the given atmospheric density rho and the tail rotor torque Q corresponding to the different tail rotor pitches0And calculating to obtain tail rotor torque Q of different tail rotor pitches under the given atmospheric density, wherein the calculation formula is as follows: in this embodiment, K is 1.
Q is tail rotor torque under a given atmospheric density state, and the unit is N.m;
Q0the tail rotor torque corresponding to different tail rotor pitches under the standard atmospheric and sea level states has the unit of N.m;
rho-given atmospheric density, kg/m3
ρ0Atmospheric density at standard atmospheric, sea level, 1.225kg/m3；
K-a correction factor that takes into account the effect of Mach number, which can be typically taken as 1, or corrected by experimentation.
4) Calculating the maximum tail pitch Pedal at a given atmospheric density2
Determining the maximum tail pitch Pedal under the steady-state torque limit according to the tail pitch torque Q of different tail pitches under the given atmospheric density2. In particular, the steady state limiting torque Q may be incorporatedSteady stateAnd a formula (5) for obtaining the maximum tail pitch Pedal under the specified atmospheric condition by an interpolation calculation method2. Maximum tail pitch Pedal2The stall angle of attack of the tail rotor is not exceeded.
5) The maximum tail pitch corresponding to the stall angle of attack of the tail rotor is Pedal3Maximum tail pitch of structural constraint is Pedal4In the state of standard atmosphere and sea levelThe maximum tail pitch corresponding to the transient limiting torque of (1) is Pedal5Then the final determined tail rotor pitch is:
Pedal＝min(Pedal2,Pedal3,Pedal4，Pedal5) (6)
the invention has the technical effects that:
1) the formula is simple and reliable, the design parameters are few, and the original design flow is basically not influenced;
2) on the premise of increasing the side wind resistance of the helicopter plateau, the additional weight cost is basically not brought;
3) the condition of flight control failure is considered, the transient limiting torque of the tail rotor cannot be exceeded even after the control failure occurs, and the flight safety is guaranteed.
The invention determines the range of the tail pitch of the helicopter by a simple and convenient calculation method, thereby improving the high-temperature and plateau crosswind resistance of the helicopter.
Take a certain helicopter tail rotor as an example:
and determining the maximum tail pitch to be 24 degrees according to the balance reaction torque and the crosswind resistance requirement of the helicopter, and the tail pitch not exceeding the transient limit torque to be 26 degrees. The steady-state limit torque is 4600n.m, and the transient limit torque is 5300 n.m.
Assuming that the pressure height is 1000m and the atmospheric temperature is-40 ℃ as a reference:
according to the pressure ratio calculation formula: Δ ═ 1-0.0065 × Hp/288.15)5.25588Calculating to obtain a pressure ratio of 0.887;
according to the temperature ratio calculation formula:
the temperature ratio is 0.809;
according to a density ratio calculation formula:
the density ratio is 1.096;
by the formula
Calculated is not more thanThe tail pitch of the over-steady state limiting torque is 27 °.
And combining the stall attack angle and the structural limit to finally obtain the maximum tail pitch of 26 degrees.
Claims (8)
1. A helicopter tail pitch range design method based on atmospheric density change is characterized by comprising the following steps,
determining the initial maximum tail pitch: obtaining a tail pitch range according to the balance reactive torque requirement and the crosswind resistance requirement of the helicopter, and determining the preliminary maximum tail pitch Pedal1；
Determining a maximum torque limit: obtaining tail rotor torque Q corresponding to different tail rotor pitches under standard atmospheric and sea level states according to the obtained tail rotor pitch range0And determining the maximum torque limit Qmax(ii) a The maximum torque limit QmaxIncluding steady state torque limit QSteady stateAnd transient torque limit QTransient state；
Calculating the tail rotor torque at a given atmospheric density: according to the given atmospheric density rho and the tail rotor torque Q corresponding to the different tail rotor pitches0Calculating to obtain tail rotor torque Q of different tail rotor pitches under given atmospheric density;
calculating the maximum tail pitch for a given atmospheric density: limiting Q according to the steady state torqueSteady stateAnd calculating the maximum tail rotor pitch Pedal under the condition of the given atmospheric density rho2；
Determining the actual maximum tail pitch Pedal: determining the maximum tail pitch corresponding to the stalling angle of the tail rotor as Pedal3Maximum tail pitch of structural constraint is Pedal4Transient limiting torque Q in standard atmospheric and sea level conditionsTransient stateThe corresponding maximum tail pitch is Pedal5And maximum tail rotor pitch Pedal for said given atmospheric density ρ2Selecting Pedal2、Pedal3、Pedal4、Pedal5The minimum value in (1) is the actual maximum tail pitch, padal.
2. The method of designing a tail pitch range of a helicopter according to claim 1, wherein the calculation formula for calculating the tail rotor torque at a given atmospheric density is,
q is tail rotor torque under a given atmospheric density state, and the unit is N.m;
Q0the tail rotor torque corresponding to different tail rotor pitches under the standard atmospheric and sea level states has the unit of N.m;
rho-given the atmospheric density, in kg/m3
ρ0Atmospheric density in standard atmospheric, sea level conditions, in units of 1.225kg/m3；
K — a correction coefficient considering the influence of the mach number, is generally 1, or is corrected by experiment.
3. The helicopter tail pitch range design method of claim 1, wherein the steady state torque limit is a maximum torque that a helicopter is allowed to use during normal flight, and the transient limit torque is a maximum torque that a pilot is not allowed to use intentionally during flight but is allowed to reach for a short time due to external environmental influences.
4. Helicopter tail pitch range design method according to claim 1, characterized in that the maximum tail pitch Pedal2Not exceeding the transient torque limit Q allowed by the helicopter in the lowest temperature and highest pressure environmentTransient stateCorresponding tail rotor pitch.
5. Helicopter tail pitch range design method according to claim 4, characterized in that the maximum tail pitch Pedal2The stall angle of attack of the tail rotor is not exceeded.
6. Helicopter tail pitch range design method according to claim 1, characterized in that the tail pitch range is derived from the derived tail pitch rangeObtaining tail rotor torque Q corresponding to different tail rotor pitches under standard atmospheric and sea level states through tail rotor table test0。
7. Helicopter tail pitch range design method according to claim 6, characterized in that the preliminary maximum tail pitch Pedal is based on the preliminary maximum tail pitch1The maximum torque limit Q max is determined by tail rotor bench testing.
8. The method for designing the range of the tail pitch of the helicopter according to claim 1, wherein the tail pitch torque Q corresponds to different tail pitches under standard atmospheric and sea level conditions0Determining the limiting torque Q in the transient stateTransient stateLower maximum tail pitch Pedal5。
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| CN103558839A (en) * | 2013-10-31 | 2014-02-05 | 新誉集团有限公司 | Small-sized unmanned helicopter rotor system propeller pitch calibration system and calibration method |
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| CN105667786A (en) * | 2016-01-12 | 2016-06-15 | 清华大学深圳研究生院 | Tail rotor driving system of helicopter, control method thereof and helicopter |
| CN108090302A (en) * | 2018-01-04 | 2018-05-29 | 北京中航智科技有限公司 | A kind of helicopter flight mechanical simulation method and system |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103558839A (en) * | 2013-10-31 | 2014-02-05 | 新誉集团有限公司 | Small-sized unmanned helicopter rotor system propeller pitch calibration system and calibration method |
| CN104915476A (en) * | 2015-05-15 | 2015-09-16 | 北京理工大学 | Ducted propeller equivalent advance ratio working condition calculation method |
| CN105667786A (en) * | 2016-01-12 | 2016-06-15 | 清华大学深圳研究生院 | Tail rotor driving system of helicopter, control method thereof and helicopter |
| CN108090302A (en) * | 2018-01-04 | 2018-05-29 | 北京中航智科技有限公司 | A kind of helicopter flight mechanical simulation method and system |
Non-Patent Citations (3)
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| JIE LI等: "Geometric Pseudospectral Method on SE(3) for Rigid-Body Dynamics with Application to Aircraft", 《HINDAWI》 * |
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