阅读说明：本技术 一种适用于中小型无人倾转旋翼飞行器的旋翼气动外形 (Rotor wing pneumatic appearance suitable for small and medium-sized unmanned tilt rotor wing aircraft ) 是由 招启军 张航 张夏阳 王博 陈希 赵国庆 于 2020-06-19 设计创作，主要内容包括：本发明涉及一种适用于中小型无人倾转旋翼飞行器的旋翼气动外形,其特征在于,包括：三片桨叶,各所述桨叶均包含从桨根至桨尖分布的第一基础翼型A、第二基础翼型A、第一基础翼型B和第二基础翼型B。本发明能够保证满足该倾转旋翼设计需求的倾转旋翼机在悬停和巡航两种工况中都能表现出较优的气动性能。(The invention relates to a rotor wing aerodynamic shape suitable for a small and medium-sized unmanned tilting rotor wing aircraft, which is characterized by comprising the following components in percentage by weight: the blade comprises three blades, and each blade comprises a first base airfoil A, a second base airfoil A, a first base airfoil B and a second base airfoil B which are distributed from a blade root to a blade tip. The invention can ensure that the tilt rotor aircraft meeting the design requirement of the tilt rotor aircraft can show better aerodynamic performance in hovering and cruising working conditions.)

1. The utility model provides a rotor aerodynamic profile suitable for unmanned rotor craft that verts of middle-size and small-size, its characterized in that includes: the blade comprises three blades, and each blade comprises a first base airfoil A, a second base airfoil A, a first base airfoil B and a second base airfoil B which are distributed from a blade root to a blade tip.

2. The aerodynamic profile of a rotor wing suitable for a small and medium sized unmanned tilt rotor aircraft according to claim 1, wherein the first base profile A is arranged at the position of the blade 0.2R, the chord length contraction ratio of the first base profile A is 165-166 mm, the installation angle of the first base profile A is 22-23 degrees, and R is the radius of the blade.

3. The rotor wing aerodynamic profile suitable for the small and medium-sized unmanned tilt rotor aircraft according to claim 1, wherein the second basic wing profile A is arranged at the position of the blade 0.8R, the chord length contraction ratio of the second basic wing profile A is 93-94 mm, the installation angle of the second basic wing profile A is-1.7-1.6 degrees, and R is the radius of the blade.

4. The aerodynamic profile of a rotor wing suitable for a small and medium-sized unmanned tilt rotor aircraft according to claim 1, wherein the first basic wing profile B is arranged at the position of the blade 0.9R, the chord length contraction ratio of the first basic wing profile B is 84-85 mm, the installation angle of the first basic wing profile B is-5.0-4.0 degrees, and R is the radius of the blade.

5. The rotor wing aerodynamic profile suitable for the small and medium unmanned tilt rotor aircraft according to claim 1, wherein the second basic wing profile B is arranged at the position of the blade 1.0R, the chord length contraction ratio of the second basic wing profile B is 77-78 mm, the installation angle of the second basic wing profile B is-7.0-6.0 degrees, and R is the radius of the blade.

6. The aerodynamic profile of a rotor for a small to medium sized unmanned tiltrotor aircraft as claimed in claim 4, wherein the pitch axis of the blade is positioned chordally from an airfoil leading edge 1/4.

Technical Field

The invention relates to the field of rotor aerodynamics and computational fluid mechanics, in particular to a rotor aerodynamic profile suitable for a small and medium-sized unmanned tilt rotor aircraft.

Background

The concept of the tilt rotor aircraft is firstly proposed by American Bell corporation, and after the technical exploration of nearly 50 years and the technical verification of test aircraft types such as XV-3, XV-15 and the like, the practical tilt rotor aircraft 'V-22 osprey' is successfully developed in the last 90 years, and is currently in service in the America army. While its upgraded improved model "V-280 warrior" is also in the stage of flight trial. The appearance of the tilt rotor aircraft provides a new idea for the operation mode of modern military battles.

The above-mentioned foreign mature tilt rotor aircraft developed special rotor aerodynamic shape design to the peculiar basic design parameter (such as maximum takeoff weight, engine effective power, cruise speed, etc.) of each type of aircraft during development. These basic design parameters are embodied in the geometric parameters of the final rotor aerodynamic profile by various design methods, such as chord length distribution, twist distribution, airfoil distribution, blade radius, blade count, and the like. However, the military significance of tiltrotors is such that the detailed design of critical components (e.g., rotors) is often kept confidential. Which in turn allows the number of tilt rotors currently publicly available to be indexed.

On the other hand, as the technical conditions of aeroengines, mechanical transmission, materials and the like are different from those of foreign countries, the simulation and the modification of the key parts are difficult to realize, and the special rotor wing is difficult to customize according to specific domestic requirements. This is also an important reason why the development of domestic tiltrotor aircraft is slow.

At present, few rotor aerodynamic profiles with three blades are specially designed and disclosed for double-rotor small and medium-sized (the maximum takeoff weight is less than or equal to 100kg) unmanned tilt rotor aircraft.

Disclosure of Invention

The invention aims to provide a rotor wing aerodynamic shape suitable for a small and medium-sized unmanned tilt rotor aircraft, which can meet the vertical take-off and landing requirements and provide guarantee for high-speed cruising and large voyage.

In order to achieve the purpose, the invention provides the following scheme:

the utility model provides a rotor aerodynamic profile suitable for unmanned rotor craft that verts of middle-size and small-size, includes: the blade comprises three blades, and each blade comprises a first base airfoil A, a second base airfoil A, a first base airfoil B and a second base airfoil B which are distributed from a blade root to a blade tip.

Optionally, the first basic airfoil a is arranged at the position of the blade 0.2R, the chord length shrinkage ratio of the first basic airfoil a is 165-166 mm, the installation angle of the first basic airfoil a is 22-23 degrees, and R is the radius of the blade.

Optionally, the second base airfoil a is arranged at the position of the blade 0.8R, the chord length contraction ratio of the second base airfoil a is 93-94 mm, the installation angle of the second base airfoil a is-1.7-1.6 degrees, and R is the radius of the blade.

Optionally, the first base airfoil B is arranged at the position of the blade 0.9R, the chord length contraction ratio of the first base airfoil B is 84-85 mm, the installation angle of the first base airfoil B is-5.0 to-4.0 degrees, and R is the radius of the blade.

Optionally, the second base airfoil B is arranged at 1.0R of the blade, the chord length shrinkage ratio of the second base airfoil B is 77-78 mm, the installation angle of the second base airfoil B is-7.0 to-6.0 °, and R is the radius of the blade.

Optionally, the pitch axis of the blade is located chord-wise from the airfoil leading edge 1/4.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

the invention provides a rotor wing pneumatic shape suitable for a small and medium-sized unmanned tilting rotor aircraft, which considers two different working conditions of hovering and forward flying cruising states of the tilting rotor aircraft to provide different design requirements for a rotor wing when selecting a wing section, simultaneously considers the constraint of part of the wing section from a blade structure, selects a thin wing section to be arranged at a blade tip part, and selects a thick wing section at a blade root part. The two wing profiles can provide better aerodynamic performance within a larger attack angle range, thereby ensuring that the rotor wing can show better aerodynamic performance in two working conditions.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic view of the aerodynamic profile of a rotor wing of the invention suitable for a small and medium-sized unmanned tilt rotor aircraft;

FIG. 2 is a schematic view of a blade airfoil arrangement of the present invention;

FIG. 3 is a schematic cross-sectional view of a blade of the present invention;

FIG. 4 is a schematic view of a single blade of the present invention;

FIG. 5 is a basic airfoil for use with the present invention;

FIG. 6 is a curve of hovering efficiency with pitch angle during the vertical take-off and landing phase according to the present invention;

FIG. 7 is a plot of cruise efficiency versus pitch angle for forward flight in accordance with the present 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 invention aims to provide a rotor wing aerodynamic shape suitable for a small and medium-sized unmanned tilt rotor aircraft, which can meet the vertical take-off and landing requirements and provide guarantee for high-speed cruising and large voyage.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Fig. 1 is a schematic view of the aerodynamic shape of a rotor wing of the invention, which is suitable for a small and medium-sized unmanned tilt rotor aircraft. FIG. 2 is a schematic view of a blade airfoil arrangement of the present invention. Fig. 3 is a schematic cross-sectional view of a blade of the present invention. Fig. 4 is a schematic view of a single piece blade of the present invention. FIG. 5 is a basic airfoil for use with the present invention.

As shown in fig. 1, a rotor aerodynamic profile suitable for a small and medium-sized unmanned tilt rotor aircraft includes: the blade comprises three blades, and each blade comprises a first base airfoil A _1, a second base airfoil A _2, a first base airfoil B _3 and a second base airfoil B _4 which are distributed from a blade root to a blade tip.

The specific geometric parameters of the airfoil at the characteristic spanwise position on the blade after being adjusted by the chord length _5 are as follows: the first base airfoil A _1 is arranged at a blade 0.2R _7, the chord length _5 scaling ratio of the first base airfoil A _1 is 165-166 mm, the erection angle _11 of the first base airfoil A _1 is 22-23 degrees, and R is the blade radius. The second base airfoil A _2 is arranged at the position of a blade 0.8R _8, the chord length _5 scaling ratio of the second base airfoil A _2 is 93-94 mm, and the erection angle _11 of the second base airfoil A _2 is-1.7-1.6 degrees. The first base airfoil profile B _3 is arranged at the position of a blade 0.9R _9, the chord length _5 reduction ratio of the first base airfoil profile B _3 is 84-85 mm, and the erection angle _11 of the first base airfoil profile B _3 is-5.0-4.0 degrees. The second base airfoil profile B _4 is arranged at the position of a blade 1.0R _10, the chord length _5 scaling ratio of the second base airfoil profile B _4 is 77-78 mm, and the erection angle _11 of the second base airfoil profile B _4 is-7.0-6.0 degrees. Pitch axis _6 of the blade is located chord-wise from airfoil leading edge 1/4.

In fig. 2 and 3, 12 is the plane of the rotor disk, 13 is the rotor shaft, 14 is the hub center, and the intersection of the blade pitch axis 6 and the rotor shaft 13 is the center of rotation of the rotor, i.e., the hub center 14.

The rotor aerodynamic profile suitable for the small and medium-sized unmanned tilt rotor aircraft is characterized in that the basic airfoil profile of the blade, which is referred to by the blades at different radial positions r, is divided into two types: and taking the basic airfoil A as a reference and taking the basic airfoil B as a reference at 0.2R _ 7-0.8R _8, and taking the basic airfoil B as a reference at 0.9R _ 9-1.0R _10, and performing chord length scaling on the chord lengths of the corresponding basic airfoil A and the basic airfoil B at other spanwise positions R according to the following table to obtain the blade airfoil. According to the aerodynamic shape of the rotor wing suitable for the small and medium-sized unmanned tilt rotor aircraft, the aerodynamic shape of the rotor wing can be obtained by carrying out the size reduction ratio of the chord length _5 on the original chord length _5 of the corresponding basic airfoil A, B according to the table 1 on each blade at other spanwise positions except the characteristic spanwise positions (0.2R _7,0.8R _8,0.9R _9 and 1.0R _ 10). Table 1 is the aerodynamic profile parameter distribution of the tiltrotor blades as follows:

TABLE 1 Tilt rotor blade aerodynamic profile parameter distribution

Table 2 is the airfoil aerodynamic performance requirements. The basic airfoil a and the basic airfoil B should satisfy not only the high-speed airfoil but also the corresponding lift coefficient CL and lift ratio in the states of mach number Ma, reynolds number Re, angle of attack AoA in table 2, as shown in table 2:

TABLE 2 Airfoil aerodynamic Performance requirements

The invention provides a rotor wing aerodynamic shape suitable for a small and medium-sized unmanned tilt rotor aircraft, which consists of three blades, wherein a basic wing section A (the relative thickness is 17-22%) is selected to be arranged at the equal positions of a blade root and the inner side of the blade, and a basic wing section B (the relative thickness is 8-10%) is selected to be arranged in the area near the blade tip in consideration of the factors of structure, drag reduction, specific working conditions and the like. Table 3 is the base airfoil profile coordinates. Specific airfoil profile coordinate points are shown in the following table:

TABLE 3 basic airfoil profile coordinates

FIG. 6 is a curve of hover efficiency versus pitch angle during the VTOL phase of the present invention. FIG. 7 is a plot of cruise efficiency versus pitch angle for forward flight in accordance with the present invention.

The tilting rotor pneumatic appearance suitable for the small and medium-sized unmanned tilting rotor aircraft provided by the invention not only meets the vertical take-off and landing requirements of the tilting rotor aircraft like a helicopter rotor, but also meets the requirements of high speed and large voyage in the cruise stage like a propeller of a fixed-wing propeller aircraft. The preferred operating condition of the auxiliary rotor can be seen in fig. 7: the range of the pitch stroke when the rotor wing of the helicopter is used is 11-15 degrees, and when the rotor wing is used as a propelling propeller of a fixed-wing airplane, the speed of the rotor wing tip reaches Mach number of 0.6, and the range of the pitch stroke when the advancing ratio is 0.2 is 17-21 degrees.

The invention discloses a rotor wing aerodynamic profile suitable for a small and medium-sized unmanned tilt rotor aircraft, which consists of three blades and is suitable for double-rotor type and small and medium-sized unmanned tilt rotor aircraft. The blade is different from a conventional helicopter blade and also different from a conventional propeller. By considering the characteristics and working states of the blades and the propellers of the helicopter in a design method and carrying out proper compromise consideration at the position where the design requirements of the blades and the propellers are contradictory, the key design requirements such as hovering efficiency, cruising efficiency and maximum takeoff weight are met, and finally the aerodynamic shape has the capability of providing aerodynamic tension for the aircraft in two different flight states and meets the use requirements of small and medium-sized unmanned tilt rotor aircraft.

The rotor aerodynamic profile has the main working characteristics on a tilt rotor aircraft:

when the tilt rotor aircraft with the rotor wing is in the taking-off and landing stages, once the design requirements of the rotor wing are met by the engine speed, the rotor wing collective pitch and the like, the rotor wing with the aerodynamic shape generates relative motion with the ambient air through rotation. Because effort and reaction force principle, the air has produced vertical ascending lift to the rotor can mention whole frame rotor craft that verts.

When the rotor craft that verts possesses the certain preceding speed of flying and will transition to the preceding mode of flying, the mechanism of verting on the fuselage drives the rotor and verts forward under corresponding control, and it is perpendicular with ground to reach rotor oar dish plane, and the gyroplane that verts this moment gets into the mode of cruising. In this mode, the air forces on the rotor produce a tractive effect on the fuselage, overcoming the fuselage's resistance. Because the aerodynamic shape of the rotor meets the aerodynamic requirement during cruise, the forward flight speed limit caused by shock waves and a reverse flow region during forward flight of the conventional helicopter can be avoided in the flight mode, and the forward flight speed which is much higher than that of the conventional helicopter can be realized.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The principles and embodiments of the present invention have been described herein using specific examples, which are presented solely to aid in the understanding of the apparatus and its core concepts; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.