阅读说明：本技术 一种旋翼桨叶结冰气动特性评估方法、电子产品和存储装置 (Rotor blade icing aerodynamic characteristic evaluation method, electronic product and storage device ) 是由 曹普孙 张威 潘喜英 胡偶 吴林波 于 2020-04-30 设计创作，主要内容包括：本发明属于旋翼桨叶防/除冰设计领域,综合考虑直升机的云雾结冰环境、桨叶流场特性、桨叶水滴撞击特性和桨叶结冰参数影响等因素提出一种旋翼桨叶结冰气动特性评估方法、电子产品和存储装置。基于直升机飞行包线评估旋翼桨叶剖面气动环境；以桨叶结冰核心影响参数作为结冰条件,执行结冰分析方法,确定桨叶结冰核心影响水滴直径；以桨叶结冰核心影响水滴直径为结冰条件,再次采用结冰分析方法进一步求解桨叶冰型,并基于该桨叶冰型确定桨叶防除冰防护范围。为桨叶加热组件控制率设计提供依据,从而提升直升机复杂云雾结冰环境作战能力。(The invention belongs to the field of rotor blade anti-icing/deicing design, and provides a rotor blade icing aerodynamic characteristic evaluation method, an electronic product and a storage device by comprehensively considering factors such as a cloud and fog icing environment, blade flow field characteristics, blade water droplet impact characteristics and blade icing parameter influence of a helicopter. Evaluating a rotor blade profile aerodynamic environment based on a helicopter flight envelope; taking the blade icing core influence parameters as icing conditions, executing an icing analysis method, and determining the diameter of the water drops influenced by the blade icing core; and taking the diameter of water drops influenced by the icing core of the blade as an icing condition, further solving the blade ice type by adopting an icing analysis method, and determining the blade ice prevention and control protection range based on the blade ice type. The control rate design method provides basis for the control rate design of the blade heating assembly, and therefore the fighting capacity of the helicopter in the complex cloud and fog icing environment is improved.)

1. A method for assessing aerodynamic characteristics of rotor blade icing, the method comprising the steps of:

s1: evaluating the aerodynamic environment of a rotor blade section based on the flight envelope of the helicopter, wherein the aerodynamic environment comprises the aerodynamic angle of attack and the incoming flow Mach number of the blade section;

s2: taking the blade icing core influence parameters as icing conditions, executing an icing analysis method, and determining the diameter of the water drops influenced by the blade icing core;

s3: and taking the diameter of water drops influenced by the icing core of the blade as an icing condition, further solving the blade ice type by adopting an icing analysis method, and determining the blade ice prevention and control protection range based on the blade ice type.

2. The method of claim 1, wherein the rotor blade icing aerodynamic characteristic is estimated by: in step S1, a helicopter flight dynamics model is built through a vortex theory and a phyllotactic theory to trim to obtain the aerodynamic angle of attack of the blade section, and the incoming flow Mach number is obtained through a first formula of the incoming flow Mach number of the equivalent blade two-dimensional flow field.

3. The method of claim 2, wherein the rotor blade icing aerodynamic characteristic is estimated by: assuming that each section airfoil section of the rotor blade has no spanwise flow, obtaining an airfoil section aerodynamic environment for icing calculation through a first formula of an equivalent blade two-dimensional flow field incoming flow Mach number, wherein the first formula is as follows:

wherein the content of the first and second substances,

M_2Dthe mach number of the incoming flow, Cp, of the airfoil section under icing conditions_maxMaximum pressure coefficient of airfoil section, M_tipThe blade tip mach number.

4. The method of claim 1, wherein the rotor blade icing aerodynamic characteristic is estimated by: in step S2, the icing environment adopts the icing envelope of annex C of CCAR-29, including the maximum continuous icing envelope and the maximum intermittent icing envelope, and the blade icing core influence parameter is used as the icing condition to execute the icing analysis method.

5. The rotor blade icing aerodynamic characteristic assessment method according to claim 4, wherein: the blade icing core influence parameter determining method is characterized in that the water drop diameter is used as a variable, the water drop collection rate of each airfoil section of the blade in two types of icing environments is analyzed, and the water drop diameter corresponding to the most severe state of the water drop collection rate of the blade is obtained.

6. The method of claim 1, wherein the rotor blade icing aerodynamic characteristic is estimated by: the icing analysis method obtains the flow field and water drop impact characteristics of the blade when icing based on the aerodynamic environment and the icing condition; the icing analysis method adopts an unsteady N-S equation and a gas-liquid two-phase flow method to simulate the growth process of an ice layer.

7. The method of claim 6, wherein the rotor blade icing aerodynamic characteristic is estimated by: the icing analysis method specifically comprises the following steps:

s2.1: generating an airfoil grid;

s2.2: solving the characteristics of the airfoil unsteady flow field by adopting gas-liquid two-phase flow according to the icing condition and the blade section pneumatic environment;

s2.3: calculating a first ice type after the specified icing time by adopting a thermodynamic model;

s2.4: generating a new airfoil grid by adopting a deformed grid technology, and solving the characteristics of an airfoil unsteady flow field by adopting gas-liquid two-phase flow according to an icing condition and a blade section pneumatic environment; calculating a second ice type after the specified icing time by adopting a thermodynamic model;

s2.5: comparing the thicknesses of the first ice model and the second ice model, finishing the comparison if the thicknesses of the first ice model and the second ice model are the same, and simultaneously obtaining the flow field and water drop impact characteristics when the paddle is frozen; otherwise, returning to the step 2.1.

8. An electronic product capable of performing the rotor blade icing aerodynamic characteristic assessment method according to any one of claims 1-7.

9. A storage device having stored therein a program executable on a computer for performing the method of assessing rotor blade icing aerodynamic characteristics according to any one of claims 1-7.

Technical Field

The invention belongs to the field of rotor blade anti-icing/deicing design, and provides a rotor blade icing aerodynamic characteristic evaluation method, an electronic product and a storage device by comprehensively considering factors such as a cloud and fog icing environment, blade flow field characteristics, blade water droplet impact characteristics and blade icing parameter influence of a helicopter.

Background

The helicopter flight performance meets the design requirements and becomes a serious difficulty in model development in order to meet the all-weather combat requirements of the helicopter, realize the flight in the cloud and fog icing environment and overcome the adaptability of the rotor in the icing environment. The icing of the rotor seriously affects the aerodynamic efficiency of the blade airfoil, so that the lift force of the rotor is reduced, the required power is increased, even the dynamic stability and the vibration characteristic of the whole helicopter are affected, and the flight safety of the helicopter is endangered. In order to ensure the flight safety of the helicopter under the cloud and fog icing environment condition, an anti-icing/deicing system needs to be additionally arranged on a rotor wing system, and the research on the icing aerodynamic characteristics of rotor wing blades is the basis of rotor wing anti-icing/deicing design.

Therefore, the icing characteristics of the rotor blades in different cloud and mist icing environments in the flight envelope of the helicopter need to be effectively evaluated, the icing range and the icing speed of the blades can be determined, an accurate blade icing protection range is provided for a rotor anti-icing/deicing system, a basis is provided for the design of the control rate of the blade heating assembly, and the fighting capacity of the complex cloud and mist icing environment of the helicopter is improved.

Disclosure of Invention

The invention aims to provide a rotor blade icing characteristic evaluation method, an electronic product and a storage device which meet the requirement of a helicopter flight envelope, which are used for designing a heating component of a rotor wing anti-icing/deicing system and improving the flight capability of a helicopter in a complex cloud and fog icing environment.

The invention provides a rotor blade icing aerodynamic characteristic evaluation method, which comprises the following steps:

s1: evaluating the aerodynamic environment of a rotor blade section based on the flight envelope of the helicopter, wherein the aerodynamic environment comprises the aerodynamic angle of attack and the incoming flow Mach number of the blade section;

s2: taking the blade icing core influence parameters as icing conditions, executing an icing analysis method, and determining the diameter of the water drops influenced by the blade icing core;

s3: and taking the diameter of water drops influenced by the icing core of the blade as an icing condition, further solving the blade ice type by adopting an icing analysis method, and determining the blade ice prevention and control protection range based on the blade ice type.

Further, in step S1, a helicopter flight dynamics model is established through a vortex theory and a phyllotactic theory to trim to obtain an aerodynamic angle of attack of a blade section, and an incoming flow mach number is obtained through a first formula of an equivalent blade two-dimensional flow field incoming flow mach number.

Further, assuming that each section airfoil section of the rotor blade has no spanwise flow, obtaining an airfoil section aerodynamic environment for icing calculation by using a first formula of an equivalent blade two-dimensional flow field incoming flow mach number, wherein the first formula is as follows:

wherein the content of the first and second substances,

M_2Dthe mach number of the incoming flow, Cp, of the airfoil section under icing conditions_maxMaximum pressure coefficient of airfoil section, M_tipThe blade tip mach number.

Further, in step S2, the icing environment adopts the icing envelope of annex C of the CCAR-29 section, including the maximum continuous icing envelope and the maximum intermittent icing envelope, and the blade icing core influence parameter is used as the icing condition to execute the icing analysis method.

Further, the blade icing core influence parameter determining method is characterized in that the water drop diameter is used as a variable, the water drop collection rate of each airfoil section of the blade in two types of icing environments is analyzed, and the water drop diameter corresponding to the harshest state of the water drop collection rate of the blade is obtained.

Further, the icing analysis method obtains flow field and water drop impact characteristics when the blade is iced based on the aerodynamic environment and the icing condition; the icing analysis method adopts an unsteady N-S equation and a gas-liquid two-phase flow method to simulate the growth process of an ice layer.

Further, the icing analysis method specifically comprises the following steps:

s2.1: generating an airfoil grid;

s2.2: solving the characteristics of the airfoil unsteady flow field by adopting gas-liquid two-phase flow according to the icing condition and the blade section pneumatic environment;

s2.3: calculating a first ice type after the specified icing time by adopting a thermodynamic model;

s2.4: generating a new airfoil grid by adopting a deformed grid technology, and solving the characteristics of an airfoil unsteady flow field by adopting gas-liquid two-phase flow according to an icing condition and a blade section pneumatic environment; calculating a second ice type after the specified icing time by adopting a thermodynamic model;

s2.5: comparing the thicknesses of the first ice model and the second ice model, finishing the comparison if the thicknesses of the first ice model and the second ice model are the same, and simultaneously obtaining the flow field and water drop impact characteristics when the paddle is frozen; otherwise, returning to the step 2.1.

The invention also provides an electronic product which can execute the rotor blade icing aerodynamic characteristic evaluation method.

The invention also provides a storage device, wherein a program capable of running in a computer is stored in the storage device, and the method for evaluating the icing aerodynamic characteristics of the rotor blade is executed.

The technical effects are as follows: the method can effectively calculate the blade icing condition in the flight envelope of the helicopter, and the blade icing protection range and the icing type obtained by the method are applied to the model rotor anti-icing/deicing design and are verified by a spray tower experiment.

Drawings

FIG. 1 is a schematic flow diagram of a method of analyzing airfoil icing in accordance with the present invention;

FIG. 2 is a schematic diagram of the water droplet impinging streamlines and water droplet collection coefficients of a preferred embodiment of the present invention;

FIG. 3 is a schematic illustration of a plot of maximum continuous icing condition water droplet collection rate for a preferred embodiment of the present invention;

FIG. 4 is a graph illustrating a plot of the maximum intermittent icing condition water droplet collection rate for a preferred embodiment of the present invention;

FIG. 5 is a schematic illustration of an airfoil icing rate curve in accordance with a preferred embodiment of the present invention;

FIG. 6 is a schematic view of a blade icing process according to a preferred embodiment of the present invention;

FIG. 7 is a schematic diagram showing the results of the test of applying the present invention to a spray tower of an anti-icing system.

Detailed Description

In order to make the implementation objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention. 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 scope of the present invention.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a flowchart of the analysis method in this step, and the rotor blade icing aerodynamic characteristic evaluation method of the present invention includes the following steps:

s1: evaluating a rotor blade profile aerodynamic environment based on a helicopter flight envelope;

the method comprises the steps of establishing a helicopter flight dynamics model through a vortex theory and a phyllotactic theory, carrying out balancing to obtain an aerodynamic attack angle of a blade section, and obtaining an incoming flow Mach number through a first formula of an equivalent blade two-dimensional flow field incoming flow Mach number.

The method comprises the steps of calculating the aerodynamic environment of the airfoil section for icing calculation by using an equivalent blade two-dimensional flow field incoming flow Mach number first formula under the assumption that each section airfoil section of the rotor blade has no spanwise flow.

The first formula is:wherein the content of the first and second substances,M_2Dthe mach number of the incoming flow, Cp, of the airfoil section under icing conditions_maxMaximum pressure coefficient of airfoil section, M_tipThe blade tip mach number.

S2: determining the diameter of water drops influenced by the icing core of the blade;

icing environments adopt icing envelopes (including two types, namely a maximum continuous icing envelope and a maximum discontinuous icing envelope) of the annex C of the CCAR-29 part. And (4) taking the blade icing core influence parameters as icing conditions to execute an icing analysis method.

The blade icing core influence parameter determination method comprises the following steps: and (3) analyzing the water drop collection rate of each airfoil section of the blade in the two icing environments by taking the water drop diameter as a variable to obtain the water drop diameter corresponding to the most severe state of the water drop collection rate of the blade.

The icing analysis method obtains the flow field and water drop impact characteristics of the blade when icing based on the aerodynamic environment and the icing condition; the icing analysis method adopts an unsteady N-S equation and a gas-liquid two-phase flow method to simulate the ice layer growth process, and specifically comprises the following substeps:

s2.1: generating an airfoil grid;

s2.2: solving the characteristics of the airfoil unsteady flow field by adopting gas-liquid two-phase flow according to the icing condition and the blade section pneumatic environment;

s2.3: calculating a first ice type after the specified icing time by adopting a thermodynamic model;

s2.4: generating a new airfoil grid by adopting a deformed grid technology, and solving the characteristics of an airfoil unsteady flow field by adopting gas-liquid two-phase flow according to an icing condition and a blade section pneumatic environment; calculating a second ice type after the specified icing time by adopting a thermodynamic model;

s2.5: comparing the thicknesses of the first ice model and the second ice model, finishing the comparison if the thicknesses of the first ice model and the second ice model are the same, and simultaneously obtaining the flow field and water drop impact characteristics when the paddle is frozen; otherwise, returning to the step 2.1.

S3: and taking the diameter of water drops influenced by the icing core of the blade as an icing condition, further solving the blade ice type by adopting an icing analysis method, and determining the blade ice prevention and control protection range based on the blade ice type.

The invention also provides an electronic product which can execute the rotor blade icing aerodynamic characteristic evaluation method.

The invention also provides a storage device, wherein a program capable of running in a computer is stored in the storage device, and the method for evaluating the icing aerodynamic characteristics of the rotor blade is executed.

FIG. 2 is a typical profile of a blade in a hovering icing environment of a helicopter flight envelope according to an embodiment of the present invention water droplet impingement streamlines and water droplet collection coefficients. The water drops are mainly attached to the front edge of the airfoil of the blade section, and the water drop attachment area is a main icing position. Under the same icing condition, the higher the water drop collection coefficient area is, the faster the icing rate is, and the larger the icing thickness is.

The blade icing aerodynamic characteristic evaluation method adopts the icing envelope of the appendix C of the CCAR-29 part as the icing environment condition.

Fig. 3 is a schematic diagram of a water droplet collection rate curve of a blade under a maximum continuous icing condition according to an embodiment of the invention, and fig. 4 is a schematic diagram of a water droplet collection rate curve of a blade under a maximum intermittent icing condition according to an embodiment of the invention. From the water droplet collection rate curve, one can derive: the diameter of the water drop corresponding to the most severe state of the leaf water drop collection rate is 16-22 μm (maximum continuous icing condition) and 19-20 μm (maximum discontinuous icing condition), and the diameter is used as the blade icing core influence parameter.

FIG. 5 is an airfoil icing rate according to an embodiment of the invention, and FIG. 6 is a typical profile icing condition of a helicopter hovering blade according to an embodiment of the invention at different ambient temperatures.

The evaluation method is adopted for the icing envelope of the annex C in the part CCAR-29 to determine the icing core influence parameters of the helicopter blade, the icing condition calculation analysis conditions are used as the blade icing condition calculation analysis conditions of the embodiment, the blade icing condition analysis is carried out on the flight state (flight speed, flight weight, flight height and environment temperature) in the helicopter flight envelope, and finally the icing rate and the icing thickness of each section of the blade are determined and are used as the basis of the blade icing prevention control rate and the icing protection range. FIG. 7 shows a design result according to an embodiment of the present invention, the effectiveness of the present invention is verified by a spray tower test using the helicopter blade icing evaluated by the embodiment of the present invention as a design bar for installing an anti-icing/deicing system on the helicopter blade, and the power required for the helicopter to start the anti-icing/deicing system in an icing environment is increased by only 4%, thereby satisfying the use requirements of the helicopter.

Finally, it should be pointed out that: the above examples are only for illustrating the technical solutions of the present invention, and are not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the replacements do not make the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions of the embodiments of the present invention.