Propeller aircraft and high-speed jet flow control method under slipstream influence

Abstract

The present application relates to the field of aircraft flow control, and particularly discloses a propeller aircraft and a high-speed jet flow control method under the influence of slipstream, the high-speed jet flow control method comprising: obtaining a current rotating speed r of the propeller; based on the current rotating speed r, adjusting a jet flow momentum coefficient of a slipstream influence area to C μ1 , adjusting a jet flow momentum coefficient of a non-slipstream influence area to C μ2 , wherein C μ1 +C μ2 =C μt , and C μ1 >C μ2 , C μt is a total momentum coefficient; by adjusting the jet flow momentum coefficients of the slipstream influence area and the non-slipstream influence area, the jet flow momentum coefficient C μ1 of the slipstream influence area is higher than the jet flow momentum coefficient C μ2 of the non-slipstream influence area, the slipstream influence area adopts a larger momentum coefficient, the non-slipstream influence area adopts a smaller momentum coefficient, the jet flow momentum coefficients in the two areas are reasonably distributed by considering the slipstream influence of the propeller, and efficient utilization of the jet flow momentum is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft flow control, in particular to a propeller aircraft and a high-speed jet flow control method under the influence of slipstream. BACKGROUND

[0002] In recent years, with the increasing depletion of traditional fossil energy and the continuous improvement of global environmental protection demand, the efficiency of aircraft power system has become an important direction of technical development. Propeller power device has become the core power form of small and medium-sized aircraft, especially amphibious aircraft, due to its low energy consumption, low emission and excellent subsonic flight efficiency. The amphibious aircraft has higher requirements for lift performance in complex sea conditions and short take-off and landing scenarios. The traditional lift enhancement technology gradually fails to meet the demand. The slot blowing technology can significantly enhance the anti-separation ability of boundary layer by injecting high-speed airflow into the leading edge of flap or slot, which is an effective way to improve the lift coefficient.

[0003] The slipstream generated by the propeller can significantly change the flow field characteristics around the aircraft. The complex interaction between the propeller and the main wing and the lift enhancement device increases the difficulty of aerodynamic performance prediction and optimization. The slipstream generated by the propeller has a significant impact on the aerodynamic performance of the lift enhancement device. The current design method is based on fixed jet flow distribution mode. However, the high flow velocity in the slipstream influence area causes the kinetic energy of the incoming flow to increase sharply, resulting in that the actual momentum coefficient in the slipstream influence area is much lower than the design value. The incoming flow velocity in the non-slipstream influence area is relatively low, and the actual momentum coefficient in the non-slipstream influence area is relatively high. This difference in distribution can cause the jet flow in the slipstream influence area to fail to effectively suppress boundary layer separation, and the lift enhancement efficiency to decay. The airflow in the non-slipstream influence area is wasted due to excessive blowing, and the overall efficiency is reduced.

[0004] Therefore, it is a technical problem to be solved by those skilled in the art to develop a high-speed jet flow control method applied to propeller flight to dynamically adjust the blowing momentum coefficient in different areas. SUMMARY

[0005] The present application discloses a propeller aircraft and a high-speed jet flow control method under the influence of slipstream to solve the above technical problems in the related art.

[0006] In order to solve the above problems, the technical scheme adopted by the present application is as follows:

[0007] In a first aspect, the present application provides a propeller aircraft, which comprises a main wing, a propeller and a flap. Wherein:

[0008] The propeller is arranged on the front side of the main wing, the flap is connected to the rear side of the main wing, and the main wing is provided with a jet flow gap at the connection between the main wing and the flap, and the jet flow gap is used for jetting jet flow.

[0009] The main wing has a slipstream influence area and two non-slipstream influence areas, the slipstream influence area is located behind the propeller, and the two non-slipstream influence areas are distributed on both sides of the slipstream influence area.

[0010] In a second aspect, the application also provides a high-speed jet flow control method under slipstream influence, applied to the propeller aircraft described above, the high-speed jet flow control method comprises:

[0011] Obtaining the current rotating speed r of the propeller;

[0012] Based on the current rotating speed r, adjusting the jet flow momentum coefficient of the slipstream influence area to C μ1 , adjusting the jet flow momentum coefficient of the non-slipstream influence area to C μ2 , C μ1 +C μ2 =C μt , and C μ1 >C μ2 , C μt is the total momentum coefficient.

[0013] The technical scheme adopted by the application can achieve the following beneficial effects:

[0014] The propeller aircraft and the high-speed jet flow control method under slipstream influence of the application adjust the jet flow momentum coefficients of the slipstream influence area and the non-slipstream influence area, so that the jet flow momentum coefficient in the slipstream influence area is higher than that in the non-slipstream influence area, in the case of ensuring that the total jet flow momentum coefficient is unchanged, the slipstream influence area adopts a larger momentum coefficient, the non-slipstream influence area adopts a smaller momentum coefficient, the momentums of the two areas are reasonably distributed by considering the slipstream influence of the propeller, the jet flow momentum distribution is balanced, the jet flow momentum in the slipstream influence area has a lift-increasing effect on the propeller aircraft that is equivalent to that of the jet flow momentum in the non-slipstream influence area, efficient utilization of jet flow momentum is realized, and the lift-increasing effect of jet flow control can be further improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0016] Figure 1 is one of the structural schematic diagrams of the propeller aircraft of the embodiment of the application;

[0017] Figure 2 is the second structural schematic diagram of the propeller aircraft of the embodiment of the application;

[0018] Figure 3 Figure 1 is a flow chart of a high-speed jet flow control method under the influence of slipstream according to an embodiment of the present application.

[0019] In the figure:

[0020] 100, main wing; 100a, slipstream influence area; 100b, non-slipstream influence area; 200, propeller; 300, flap; 400, jet flow gap; 500, flowmeter. DETAILED DESCRIPTION

[0021] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0022] The terms "first", "second", and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are usually a class, not limited to the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / ", generally represents a "or" relationship between the front and rear associated objects.

[0023] The embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. Figures 1 to 3 The propeller aircraft and high-speed jet flow control method under the influence of slipstream provided by the embodiments of the present application will be described in detail through specific embodiments and application scenarios.

[0024] Please refer to Figure 1 and Figure 2 The embodiments of the present application disclose a propeller aircraft, the disclosed propeller aircraft comprises a body, a main wing 100, a propeller 200 and a flap 300, wherein the main wing 100 is connected with the body, the propeller 200 is arranged on the front side of the main wing 100, the flap 300 is connected on the rear side of the main wing 100, and the main wing 100 is provided with a jet flow gap 400 at the connection position of the main wing 100 and the flap 300. High-pressure airflow is introduced from the cavity of the main wing 100 or an external air compressor, and a high-speed jet flow is formed on the upper surface of the flap 300 at a certain angle (for example, 30°) through the jet flow gap 400, so as to compensate the boundary layer kinetic energy and delay the airflow separation.

[0025] When the propeller of the propeller aircraft rotates, the blades push the air to generate thrust, and the air being pushed forms a high-speed airflow, that is, a slipstream, which flows downstream and affects the aerodynamic performance of other components of the propeller aircraft. In the embodiment of the present application, the main wing 100 has a slipstream influence area 100a and a non-slipstream influence area 100b, wherein the slipstream influence area 100a is located behind the propeller 200, and the portions of the main wing 100 on both sides of the slipstream influence area 100a form the non-slipstream influence area 100b. From the extension direction of the main wing 100, the propeller 200 and the non-slipstream influence area 100b are distributed in a staggered manner. Based on the speed-increasing effect of the propeller 200 on the airflow when rotating, the airflow flow speed in the slipstream influence area 100a is greater than that in the non-slipstream influence area 100b.

[0026] The lift increment of the propeller aircraft is positively correlated with the jet momentum coefficient, and the momentum coefficient expression is:

[0027]

[0028] In the above formula, ρ is the jet density, U j is the jet speed, A j is the outlet area, ρ ∞ is the incoming flow density, U ∞ is the incoming flow speed, A ref is the reference area. It can be found that, in the case of achieving the same jet momentum coefficient C μ , the higher the incoming flow speed U ∞ , the greater the required flow rate ρU j A j .

[0029] In the related art, the incoming flow speed U ∞ is usually set as the flight speed of the aircraft, without considering the influence of the slipstream generated by the propeller 200. The jet momentum of the slipstream influence area 100a and the jet momentum of the non-slipstream influence area 100b are set to be the same. However, as known from the foregoing, the slipstream generated by the propeller 200 can increase the airflow flow speed on the surface of the main wing 100 in the rear region. In the case of using the same jet momentum coefficient for the slipstream influence area 100a and the non-slipstream influence area 100b, the jet momentum in the slipstream influence area 100a has a smaller lift-increasing effect on the propeller aircraft than the jet momentum in the non-slipstream influence area 100b, resulting in a decrease in the jet utilization efficiency. In other words, based on the influence of the slipstream generated by the propeller 200, a greater jet momentum is required in the slipstream influence area 100a than in the non-slipstream influence area 100b.

[0030] Based on this situation, the embodiment of the present application further discloses a high-speed jet control method under the influence of a slipstream, please refer to Figure 3, the high-speed jet flow control method under the influence of slipstream includes the following steps:

[0031] S100, acquiring a current rotating speed r of the propeller 200;

[0032] S200, adjusting the jet flow momentum coefficient of the slipstream influence area 100a to C μ1 and adjusting the jet flow momentum coefficient of the non-slipstream influence area 100b to C μ2 , C μ1 +C μ2 =C μt , C μ1 >C μ2 , C μt is a total momentum coefficient.

[0033] In the above scheme, the current rotating speed r of the propeller 200 can be acquired by various ways such as Hall sensor, photoelectric encoder and motor controller, based on the current rotating speed r, the jet flow momentum coefficients of the slipstream influence area 100a and the non-slipstream influence area 100b are adjusted, so that the jet flow momentum coefficient C μ1 of the slipstream influence area 100a is higher than the jet flow momentum coefficient C μ2 of the non-slipstream influence area 100b, under the condition that the total jet flow momentum coefficient C μt is unchanged, the slipstream influence area 100a adopts a larger momentum coefficient and the non-slipstream influence area 100b adopts a smaller momentum coefficient, this way of reasonably distributing the jet flow momentum coefficients of the two areas by considering the slipstream influence of the propeller 200 can balance the jet flow momentum distribution, so that the lift-increasing effect of the jet flow momentum in the slipstream influence area 100a on the propeller aircraft is equivalent to the lift-increasing effect of the jet flow momentum in the non-slipstream influence area 100b on the propeller aircraft, realizing efficient use of jet flow momentum and further improving the lift-increasing effect of jet flow control.

[0034] In an alternative embodiment, based on the current rotating speed r, the jet flow momentum coefficient of the slipstream influence area 100a is adjusted to C μ1 and the jet flow momentum coefficient of the non-slipstream influence area 100b is adjusted to C μ2 , which includes the following steps:

[0035] S210, acquiring a maximum rotating speed r max and a minimum rotating speed r min of the propeller 200;

[0036] S220, determining the jet flow momentum coefficient C of the slipstream influence area 100a and determining the jet flow momentum coefficient C of the non-slipstream influence area 100b, wherein C μt is a total momentum coefficient.

[0037] In the above scheme, when the rotational speed of the propeller 200 increases, the flow velocity in the slipstream influence area 100a increases, and compared with the non-slipstream influence area 100b, a higher jet flow momentum is required to match the higher flow velocity in the slipstream influence area 100a to maintain effective control on the aerodynamic surface; when the rotational speed of the propeller 200 decreases, the flow velocity in the slipstream influence area 100a is lower, and reducing the jet flow momentum of the slipstream influence area 100a can avoid over-control or energy waste, that is, the greater the current rotational speed r of the propeller 200, the greater the difference between C μ1 and C μ2 , and the smaller the current rotational speed r of the propeller, the smaller the difference between C μ1 and C μ2 . Based on the current rotational speed r of the propeller 200, the jet flow momentum coefficient C μ1 distributed in the slipstream influence area 100a and the jet flow momentum coefficient C μ2 distributed in the non-slipstream influence area 100b are dynamically adjusted, that is, the control performance of the jet control is improved, and energy is saved, thereby maintaining the best jet control effect.

[0038] In the embodiments of the present application, when adjusting the jet flow momentum coefficients of the slipstream influence area 100a and the non-slipstream influence area 100b, the jet flow momentum coefficient of the slipstream influence area 100a can be adjusted to C μ1 , and the jet flow momentum coefficient of the non-slipstream influence area 100b can be adjusted to C μ2 . For example, a high-speed jet flow source is connected to the main wing 100 through a gas supply main pipeline, and then connected to the regions corresponding to the slipstream influence area 100a and the non-slipstream influence areas 100b on both sides of the jet flow gap 400 through three branch pipelines, and a flow regulating valve is arranged on each branch pipeline, so as to realize the size adjustment of the jet flow of the jet flow gap 400 in the slipstream influence area 100a and the non-slipstream influence area 100b, and further realize the adjustment of the jet flow momentum coefficient of the slipstream influence area 100a to C μ1 and the adjustment of the jet flow momentum coefficient of the non-slipstream influence area 100b to C μ2 , C μ1 >C μ2 .

[0039] For example, in the embodiments of the present application, taking the propeller 200 with a propeller disc diameter of 536 mm, a propeller 200 rotational speed range of 900 rpm-6050 rpm, and a high-speed jet total momentum coefficient of 10% as an example, the jet flow momentum coefficient C μ1 of the slipstream influence area 100a and the jet flow momentum coefficient C μ2 of the non-slipstream influence area 100b at different rotational speeds are as follows.As shown in Table 1, more jet momentum coefficients are allocated in the slipstream influence area 100a to increase the jet momentum of the wing behind the propeller 200, and less jet momentum coefficients are allocated in the non-slipstream influence area 100b to reduce the jet momentum of the wing in the non-slipstream influence area 100b, so as to realize efficient use of jet momentum while keeping the total momentum coefficient constant.

[0040] Table 1

[0041]

[0042] In some embodiments of the present application, the slipstream influence area 100a and the non-slipstream influence area 100b can be set as relatively fixed areas. Specifically, the slipstream influence area 100a can be the area of the main wing 100 directly behind the propeller 200, and the tip of the propeller 200 can be used as the boundary between the slipstream influence area 100a and the non-slipstream influence area 100b. In this way, when the jet momentum coefficient C μ1 of the slipstream influence area 100a and the jet momentum coefficient C μ2 of the non-slipstream influence area 100b are adjusted, the control logic of the jet control can be simplified.

[0043] The inventor found in the research process that the change of the rotation speed of the propeller 200 will affect the range of the slipstream influence area 100a and the non-slipstream influence area 100b. The higher the rotation speed r of the propeller 200, the greater the thrust generated by the propeller 200, and the faster the airflow speed behind the propeller 200, which will cause the range of the slipstream influence area 100a to expand and the range of the non-slipstream influence area 100b to shrink. Conversely, the range of the slipstream influence area 100a at low rotation speed is smaller, and the range of the non-slipstream influence area 100b is larger.

[0044] Based on this situation, in the embodiments of the present application, the range of the slipstream influence area 100a and the non-slipstream influence area 100b can also be determined according to the current rotation speed r of the propeller 200. Specifically, please refer to Figure 2 In the propeller aircraft disclosed in the embodiments of the present application, the leading edge of the main wing 100 is provided with a plurality of flowmeters 500 uniformly distributed along the extension direction of the main wing 100. Exemplarily, the flowmeter 500 can be a Pitot tube installed on the main wing 100. The first flowmeter 500 is located directly behind the tip of the propeller 200, and the remaining flowmeters 500 are distributed along the extension direction of the main wing 100 to the edge of the main wing 100. Exemplarily, the disc diameter of the propeller aircraft is 536 mm, the number of Pitot tubes is 8, the distance between the first Pitot tube and the tail Pitot tube is 375.2 mm, that is, the distance between two adjacent Pitot tubes is 53.6 mm, which is 1 / 10 of the disc diameter.

[0045] Based on the above structural arrangement, the slipstream influence area 100a and the non-slipstream influence area 100b in the embodiment of the application are determined in the following manner:

[0046] The flow rate output values of the plurality of flowmeters 500 are acquired 1~ n wherein n is the number of flowmeters 500, 1 is the flow rate output value of the first flowmeter 500, n is the flow rate output value of the last flowmeter 500, it can be understood that the flow rate output value of the ith flowmeter is i ;

[0047] The current flight speed V of the propeller aircraft is acquired;

[0048] When the flow rate output value of the ith flowmeter 500 satisfies , it is determined that the ith flowmeter 500 is the demarcation point between the slipstream influence area 100a and the non-slipstream influence area 100b, the slipstream influence area 100a is located in the middle of the main wing 100, and the two non-slipstream influence areas 100b are distributed on both sides of the slipstream influence area 100a, wherein i takes the value of i≤n, m is the flowmeter number when the ith flowmeter 500 is taken as the reference, and k is the rotation speed-flight speed coefficient, 1.2≤k≤1.7.

[0049] In the above scheme, i is the flow rate output value of the ith flowmeter 500, i-2 and i-1 are the flow rate values of the two flowmeters 500 inside the ith flowmeter 500, and i+1The velocity value of the flowmeter 500 outside i, the average velocity of the four flowmeters 500, and the third flowmeter 500 selected as the node are used to determine the range of the slipstream influence area 100a and the non-slipstream influence area 100b, which can relatively increase the determination range of the slipstream influence area 100a, make the identification of the slipstream influence area 100a have a certain redundancy, and provide a buffer space for unsteady flow (such as vortex shedding and turbulent penetration), thereby providing aerodynamic safety margin. It can be understood that the airflow flow velocity of the slipstream influence area 100a is greater than that of the non-slipstream influence area 100b, and when the average velocity is less than k times the flight speed V, it can be determined that the part inside the flowmeter 500 at i is greatly affected by the slipstream, and the part outside the flowmeter 500 at i is less affected by the slipstream, and the rear of the flowmeter 500 at i can be determined as the boundary between the slipstream influence area 100a and the non-slipstream influence area 100b.

[0050] It can be understood that the airflow flow velocity is monitored by multiple Pitot tubes, so as to redivide the range of the slipstream influence area 100a and the non-slipstream influence area 100b. Since the slipstream influence area 100a and the non-slipstream influence area 100b are more finely divided, the foregoing gas supply main pipe needs to be connected to more branch pipes to adjust the jet momentum coefficient more accurately.

[0051] It should be noted that the setting of the rotation speed-flight speed coefficient k in the embodiments of the present application is related to the propeller diameter, the number of blades, the pitch angle, the installation position and the installation distance of the propeller aircraft, and therefore, the rotation speed-flight speed coefficient k can be adaptively adjusted according to different types or sizes of the propeller aircraft, and the present application does not make specific limitations thereto.

[0052] It should be noted that in this document, the terms "comprise", "comprising", or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or device that includes a series of elements not only includes those elements, but also includes other elements not explicitly listed, or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element. In addition, it should be noted that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but can also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0053] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A high-speed jet control method under slipstream influence, applied to a propeller-driven aircraft, the propeller-driven aircraft comprising a main wing (100), a propeller (200), and flaps (300), wherein, The propeller (200) is located on the front side of the main wing (100), the flap (300) is connected to the rear side of the main wing (100), and the main wing (100) has a jet slit (400) at its connection with the flap (300), the jet slit (400) is used to eject a jet, the main wing (100) has a slipstream influence zone (100a) and a non-slipstream influence zone (100b), the slipstream influence zone (100a) is located behind the propeller (200), and the two non-slipstream influence zones (100b) are distributed on both sides of the slipstream influence zone (100a). The high-speed jet control method includes: Obtain the current rotational speed r of the propeller (200); Based on the current rotational speed r, the jet momentum coefficient of the slipstream influence zone (100a) is adjusted to C. μ1 The jet momentum coefficient of the non-slip flow affected zone (100b) is adjusted to C. μ2 , where C μ1 +C μ2 =C μt And C μ1 >C μ2 C μt This is the total momentum coefficient.

2. The high-speed jet control method under the influence of slipstream according to claim 1, characterized in that, Based on the current rotational speed r, the jet momentum coefficient of the slipstream influence zone (100a) is adjusted to C. μ1 The jet momentum coefficient of the non-slip flow affected zone (100b) is adjusted to C. μ2 ,include: Obtain the maximum rotational speed r of the propeller (200) max and minimum speed r min ; Determine the jet flow coefficient of the slip flow affected zone (100a). Determine the jet momentum coefficient of the non-slip flow affected zone (100b). , where C μt This is the total momentum coefficient.

3. The high-speed jet control method under the influence of slipstream according to claim 2, characterized in that, By adjusting the flow rates in the slip-flow-affected zone (100a) and the non-slip-flow-affected zone (100b), the jet momentum coefficient of the slip-flow-affected zone (100a) is adjusted to C. μ1 The jet momentum coefficient of the non-slip flow affected zone (100b) is adjusted to C. μ2 .

4. The high-speed jet control method under the influence of slipstream according to any one of claims 1 to 3, characterized in that, The leading edge of the main wing (100) is provided with a plurality of flow meters (500) evenly distributed along the extension direction of the main wing (100), and the first flow meter (500) is located directly behind the tip of the propeller (200), while the remaining flow meters (500) extend towards the edge of the main wing (100). The slipstream-affected zone (100a) and the non-slipstream-affected zone (100b) are determined in the following manner: Obtain the flow rate output values ​​of multiple flow meters (500). 1~ n Where n is the number of the flow meters (500); Obtain the current flight speed V of the propeller aircraft; When the flow rate output value of the flow meter (500) at the i-th position satisfies At that time, the flow meter (500) at the i-th location is identified as the boundary between the slipstream influence zone (100a) and the non-slipstream influence zone (100b). The slipstream influence zone (100a) is located in the middle of the main wing (100), and the two non-slipstream influence zones (100b) are distributed on both sides of the slipstream influence zone (100a). Where i≤n, m is the flow meter number based on the i-th flow meter 500, k is the rotational speed-flight speed coefficient, and 1.2≤k≤1.

7.

5. The high-speed jet control method under the influence of slipstream according to claim 4, characterized in that, The flow meter (500) is a Pitot tube.

6. The high-speed jet control method under slipstream influence according to claim 4, characterized in that, The distance between two adjacent flowmeters (500) is 1 / 10 of the diameter of the propeller (200).

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