34 results about "Flutter" patented technology

The embodiment of the invention discloses a control method and a control device of an electromagnetic valve and a vehicle. The control method of the electromagnetic valve comprises the following steps: generating a pulse width modulation signal, wherein the frequency of the pulse width modulation signal is greater than the response frequency of the electromagnetic valve and the duty ratio of the pulse width modulation signal fluctuates periodically within a preset range so that the pulse width modulation signal is superposed with a flutter signal; and transmitting the pulse width modulation signal to the electromagnetic valve. The amplitude and the frequency of the flutter signal are respectively determined by modulating the periodic fluctuation of the duty ratio of the PWM signal in the preset range and the fluctuation range and the fluctuation period of the duty ratio of the PWM signal so that the independent adjustment of the amplitude and the frequency of the flutter signal is realized. The algorithm of the flutter signal is simplified on the basis of solving the problem of hysteresis of the electromagnetic valve due to static friction of the system or parasitic flutter of theelectromagnetic valve, and the amplitude and the frequency of the flutter signal can be better controlled according to the requirement of the hysteresis effect and thus the dynamic response characteristic of the electromagnetic valve can be better improved.

The invention relates to a method for measuring a full-motion horizontal tail rotating mode of an airplane, which comprises the following steps of: firstly, identifying an initial dimensionless frequency of a full-motion horizontal tail rotating mode by adopting a phase separation technology, and then obtaining a force frequency curve of the full-motion horizontal tail rotating mode by adopting aphase resonance mode extraction technology near the frequency and gradually increasing exciting force from small to large; when the force frequency curve of the full-motion horizontal tail rotating mode is obtained, processing the force of the exciting force by a resultant moment M. According to the method, the nonlinear influence of friction and gaps on the full-motion horizontal tail rotation mode can be more completely considered, the force-frequency curve of the full-motion horizontal tail rotation mode measured by the method is used as the input of horizontal tail flutter calculation, theflutter calculation can be considered more comprehensively and reasonably, and the flutter safety of an airplane is effectively guaranteed.

The invention provides a system and a method for testing the dynamic stiffness of an airplane horizontal tail servo actuating mechanism. The system comprises ground maintenance and detection equipment(1), a flight control computer (2), a system tester (3), a dynamic stiffness test bed and the like (4), wherein the dynamic stiffness test bed (4) comprises a dynamic stiffness test bed body (41) anda dynamic stiffness test bed control system (42). The method comprises the following steps: drawing a required dynamic stiffness amplitude-frequency characteristic curve through loading force and corresponding position feedback, and finding out the lowest point of the dynamic stiffness amplitude and the corresponding frequency value according to the drawn characteristic curve. The system can truly and effectively measure the dynamic stiffness amplitude-frequency characteristic curve, and according to the testing method, the lowest point of the dynamic stiffness amplitude of the horizontal tail servo actuator and the frequency corresponding to the lowest point can be found out, and necessary data support is provided for analyzing the airplane servo flutter phenomenon and optimizing the horizontal tail servo actuator and a gap eliminating connecting mechanism between the horizontal tail servo actuator and a control surface.

The invention discloses a method for optimizing static aeroelasticity and flutter of an all-moving horizontal tail. Firstly, a finite element model is established, then static aeroelasticity, flutterand balance weight are optimized one by one, the matching degree is high, the minimum-weight full-motion horizontal tail which meets the requirements for static aeroelasticity and flutter and does notaffect the appearance of the horizontal tail is obtained, constraint conditions are met, and the problems of static aeroelasticity and flutter of an airplane are effectively solved.

The invention discloses a method for solving the linear flutter speed of a three-dimensional wing based on a multi-body system transfer matrix method. The method comprises the following steps: deriving a bending-torsion coupling beam transfer matrix of the wing based on the multi-body system transfer matrix method; establishing a total transfer equation of the wing, and solving and obtaining the inherent frequency and the vibration mode of the wing; according to the Theodorsen unsteady aerodynamic force theory, establishing the relation between wing vibration displacement and aerodynamic force; establishing a body dynamics equation of the wing, and converting the body dynamics equation into a frequency domain to obtain a flutter frequency domain model of the wing; and performing frequencydomain solving on the wing flutter frequency domain model to obtain the flutter speed of the wing. The method can achieve the quick solving of the flutter speed of the wing.

The invention belongs to the field of structural mechanics and relates to a method for determining the dimension of a rectangular beam section of a low-speed flutter main beam model of an airplane. The method is characterized by adapting to the situation that the half width a of a rectangular section is smaller than the half height b of the rectangular section or the situation that J/Ix<1.69, wherein Ix refers to vertical inertia moment and J refers to polar inertia moment. The method for determining the dimension of the rectangular beam section with a lug piece comprises the following steps of: calculating the half width ar and the half height br of the rectangular section when the rectangular beam without the lug piece has the vertical inertia moment Ix of a preset value and the polar inertia moment J of a preset value; adjusting the polar inertia moment J with the preset value; calculating the half width a and the half height b; and calculating the half width 1 of the rectangular beam section with the lug piece when the rectangular beam with the lug piece has lateral inertia moment Iy of a preset value and the thickness of the lug piece is t. The method disclosed by the invention has the advantages of increasing the rigidity precision of the section of the model, reducing the uncertainty of model design, shortening the time for determining the dimension of the section, and increasing the design efficiency of the flutter model.

The invention provides a folding rudder capable of monitoring and optimizing the flutter phenomenon. The folding rudder comprises a folding module, a monitoring module, a processing and analyzing module and a driving module. According to the folding rudder, the flutter phenomenon is relieved or eliminated in a passive monitoring and active intervention mode, the real-time performance is achieved, the vibration condition of the folding rudder in the flight process of a guided weapon can be analyzed more accurately, and in addition, when the folding rudder of the guided weapon flutters, the problem can be solved in an active intervention mode, so that structural damage is avoided; and therefore, the vibration condition of the folding rudder in the flight process of the guided weapon can be monitored in real time, in addition, a computer analyzes and processes the data, so that the vibration of the folding rudder is relieved or counteracted in an active intervention mode, and therefore the flutter phenomenon is effectively prevented. The folding rudder has the advantages of being low in design cost, high in real-time performance, high in reliability, convenient in installation and free from influence on the original structure and equipment of the guided weapon.

The invention belongs to the field of aviation structural mechanics, and relates to a design method for obtaining the overweight ratio of a flutter model in the design of the flutter model. The method comprises the following steps of: calculating the equivalent mass mBE of a reference beam frame according to a reference beam frame model, and calculating the equivalent mass ratio nBE of the reference beam frame in combination with the component mass mA; calculating a design scale coefficient ndss; specifying a section shape coefficient ns; specifying the mass ratio kb of a flutter model beam; and calculating the overweight ratio nG of the flutter model. In According to the method disclosed by the invention, a reverse design method is used for replacing a trial and error method adopted in the conventional model design, so that various factors possibly influencing model weight and mathematical relations thereof are considered at the start of model design, the overweight ratio of the model is further obtained, the uncertainty of model design is reduced, and the model design period is shortened greatly.

The invention discloses an unsteady flow control method based on flutter winglets, and belongs to the technical field of fluid machinery. A flutter winglet is arranged near a separation point where a controlled pneumatic component generates flow separation, the flow direction of the flutter winglet is within the range of 5% L in front of and behind the separation point, L is the characteristic length of the controlled pneumatic component, and the distance between the spanwise direction of the flutter winglet and the separation point is 5%-50% of the height h of a separation area. Energy sources such as an external air source or a power source are not needed, a complex air path or a circuit system is not needed, energy can be extracted from a main stream to generate flutter only through the structure of the device, and therefore unsteady excitation used for restraining flow separation is generated, performance indexes such as the pressure ratio, the efficiency, the total pressure recovery and the stability margin of a controlled pneumatic component are improved, and the reliability of the controlled pneumatic component is improved. The system has the advantages of simple structure, no external energy source, high engineering practicability and the like.

Methods and systems for analyzing and predicting aeroelastic flutter on configurable aircraft are disclosed herein. The method may include the steps of: a) flying a known aircraft type above ground, wherein the aircraft has a payload in a known configuration; b) acquiring data from at least one sensor on the aircraft while flying above ground; c) repeating steps a) and b) with a different payload configuration; d) training a machine learning predictive model for the aircraft type for aeroelastic flutter using the collected data; and e) using the predictive model to predict when aeroelastic flutter may occur on the aircraft type when the aircraft has a payload in a new configuration for which data from sensors was not previously collected with the aircraft in flight.

The invention relates to an aeroelastic system flutter signal abnormal data expansion method. Based on a time sequence signal generation algorithm of a generator in a generative adversarial network, aflutter data set can be expanded through a pre-trained generator network by only needing a small number of flutter signals with coupling resonance occurring in structural response signals of an aeroelastic system or an aircraft, normal data and abnormal data are balanced as much as possible, and the influence of data samples on the method in the method verification process is reduced. Compared with the prior art, the flutter signal data set extension method based on the deep learning algorithm is provided by introducing the deep learning algorithm into the data set extension of the vibrationsignals of the aeroelastic system. Based on a pre-trained generative adversarial network, conversion from random signals based on Gaussian distribution to flutter signals with flutter characteristicsis achieved through a small number of actually-measured wind tunnel flutter test flutter signals of coupling resonance, and the purpose of expanding a data set is achieved.

The invention belongs to the field of aeroelastic mechanics, and particularly relates to an emergency method for flutter suppression in a low-speed flutter wind tunnel test. The emergency method comprises the steps that 1 an emergency system for flutter suppression is constructed, the emergency system comprises a low-speed flutter model and a skin damage mechanism, the low-speed flutter model comprises a frame section and a dimensional skin, and the skin damage mechanism is installed at a flutter sensitive part in the low-speed flutter model; and 2 when flutter occurs, the dimensional skin of the low-speed flutter model is damaged through the skin damage mechanism. According to the emergency method for flutter suppression in the low-speed flutter wind tunnel test, an emergency flutter suppression measure is provided, when flutter occurs, the skin damage mechanism is adopted to damage the dimensional skin of the low-speed flutter model, and the purpose of protecting the safety of the overall structure of the model at a low cost is achieved. The method is clear in principle and easy to implement, and can protect the model safety when other reversible flutter suppression measures are invalid.