JPS6317680B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an airfoil for a rotary wing used in a rotary wing aircraft such as a helicopter. The rotor blades of rotorcraft must function efficiently in different flight environments: hovering, maneuvering, and high-speed flight. For example, in hovering flight, it is necessary to improve aerodynamic efficiency in order to reduce the required horsepower as much as possible, and for this purpose, the medium Matsuha number region of about 0.4 to 0.6 and the medium lift coefficient region of about 0.6 are required. It is necessary to obtain a high lift-to-drag ratio at low speeds, and in order to suppress the drag of the forward rotor blades that operate in the transonic region during forward flight, the drag is low in the high Matsuha number and low lift coefficient regions, and conversely, at low speeds In order to prevent stalling of the retreating rotor blades that operate at large angles of attack, an airfoil with a low Matsuha number and high lift is required. Furthermore, it is important for an airfoil for a rotary blade to have a pitching moment coefficient as close to zero as possible in order to avoid placing a high load on the rotary blade control device. Traditionally, rotorcraft such as helicopters have
The NACA 00 series symmetrical airfoils are the most commonly used, with the NACA 230 series airfoils also being used for special applications; technical information on these airfoils can be found in Dover Publishing, New York. It is disclosed in detail in ``Theory of Wing Sectin'', co-authored by Abbott and Dehnhoff. However, the characteristics of these known airfoils do not fully meet the demands for improved performance of rotary-wing aircraft, which have been increasing in recent years.
Recently, there has been a movement to develop airfoils that are even better than conventional airfoils. For example, Japanese Patent Publication No. 56-42520 discloses an airfoil that has an increased maximum lift coefficient and drag divergence Matsuha number compared to conventional airfoils. Drag divergence Matsuha number is the change in drag coefficient due to change in Matsuha number.
Defined as the Matsuha number of 0.1, it is an important quantity in determining high-speed flight characteristics; a high value indicates that the airspeed of the rotor blades can be increased without a significant increase in drag. means. Furthermore, Japanese Patent Application Laid-open No. 56-95799 discloses an airfoil for a helicopter perspective wing in which the drag divergence Matsuha number is further increased than that of the airfoil according to the above-mentioned Japanese Patent Publication No. 56-42520. The present invention provides an airfoil for a rotary blade that can greatly increase the drag divergence Matsuha number without reducing the maximum lift coefficient at low speeds compared to the conventionally known airfoils as described above. The purpose is to Another object of the present invention is to provide an airfoil that exhibits excellent characteristics over a wide range of blade thickness ratio defined as the ratio of maximum blade thickness to blade chord length from 0.08 to 0.15. That is, the airfoil for a rotor according to the present invention has ±
Approximately within the range of 3%, the formula y/c ₀ = a√ ₀ + b (x/c ₀ ) + c (x/c ₀
) ² + d(x/c ₀ ) ³ , where y is the airfoil outline coordinate,
x is the position in the chord direction, C ₀ is the chord length,
a, b, c, and d are the values shown in Table 1.

【table】

[Table] The airfoil defined in this way has a blade thickness ratio of 0.12 and is called DKR-120 for convenience. Further, an airfoil for a rotary blade according to another aspect of the present invention is approximately defined by the above formula like the above-mentioned airfoil, but a, b, c, and d are the values in Table 2. Take.

[Table] The airfoil defined in this way has a blade thickness ratio of 0.105.
For convenience, it is called DKR-105. Further, in the airfoil of the rotor according to another aspect of the present invention, the coefficients a, b, c, and d in the above equation are defined by the following equation. a=l _a (t/c ₀ )+m _a b=l _b (t/c ₀ )+m _b c=l _c (t/c ₀ )+m _c d=l _d (t/c ₀ )+m _dHowever , l _a , l _b , l _c , l _d , m _a , m _b , m _c , m _d are shown in Table 3.
t is the maximum blade thickness and 0.08≦/c ₀ ≦0.150.

【table】

[Table] The airfoil according to the present invention with a blade thickness ratio of 0.08 has the values shown in Table 4 as an example.

【table】

[Table] Tables 5, 6, and 7 show the blade thickness ratio, respectively.
Examples of airfoils of 0.105, 0.120, and 0.150 are shown.

【table】

【table】

【table】

【table】

[Table] Typical shapes of rotary blade airfoils according to the present invention are shown in the first table.
As shown in the figure. As is clear from the figure, the curvature of the lower leading edge 1 of this airfoil maintains a relatively large value up to a point approximately 2% chord length from the leading edge, and the curvature sharply increases behind that point. and increases again at the trailing edge 2. The maximum blade thickness position 3 is located behind the 30% chord length point, and this position becomes further rearward as the blade thickness ratio becomes smaller. The leading edge radius r is relatively large, and the top surface is approximately
The trailing edge 4 extending from the 85% to 100% chord length point is slightly concave. Furthermore, the trailing edge 5 has a finite thickness. The airfoils in Tables 4, 5, 6, and 7 are shown in Figure 2 a, b, c,
For convenience, these are shown in DKR-080,
They are called DKR-105, DKR-120, and DKR-150. Figure 3 shows the maximum lift coefficient and drag divergence Matsuha number at Matsuha number 0.4, VR-12, VR-
13, VR-14 shows the airfoil according to the invention of Japanese Patent Application Laid-Open No. 56-95799, and SC-1095 shows the airfoil according to the invention of Japanese Patent Publication No. 56-42520. The airfoil according to the invention is DKR−
150, DKR-120, DKR-105, DKR-080, approximately on the curve designated as DKR-xx. The other points are those of other known airfoil types, and the numbers in brackets indicate the blade thickness ratio in %. As can be seen from the figure, the rotor airfoil of the present invention exhibits a significantly larger drag divergence Matscha number than the conventional airfoil. Figure 4 shows the maximum lift-drag ratio of the DKR-105 airfoil according to the present invention in comparison with the known airfoil.As is clear from this figure, the airfoil of the present invention is compared to the known airfoil. and exhibits a high maximum lift-drag ratio.

[Brief explanation of the drawing]

FIG. 1 shows a typical shape of a rotary blade airfoil according to the present invention, and FIG. 2 shows a blade thickness ratio of 0.080, 0.105, 0.120,
A diagram showing an example of a 0.150 airfoil, Figure 3 is a chart showing the maximum lift coefficient and drag divergence coefficient of the airfoil of the present invention in comparison with other airfoils, and Figure 4 is a chart showing the maximum lift-drag ratio. It is.

Claims (1)

[Claims] An airfoil for a rotor blade approximately defined by the following formula within a range of 1 ±3%. y/c ₀ =a√ ₀ +b(x/c ₀ )+c(x/c ₀
) ² + d (x/c ₀ ) ³ where y is the airfoil outline coordinate, x is the position in the chord direction, c ₀ is the chord length, and a=l _a (t/c ₀ ) + m _a b =l _b (t/c ₀ )+m _b c=l _c (t/c ₀ )+m _c d=l _d (t/c ₀ )+ _m dHowever, l _a , l _b , l _c , l _d , m _a , m _b , m _c , and m _d are according to the table below. [Table] [Table] Also, t is the maximum blade thickness and is 0.08≦t/c ₀ ≦0.150. 2. An airfoil for a rotor blade according to claim 1, which has an outer shape shown in the following table. [Table] [Table] 3. An airfoil for a rotor blade according to claim 1, which has an outer shape as shown in the following table. [Table] [Table]