Plasma Actuator Flow Control for Rotary Wing Blade Stall
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cyclic pitch mechanisms in rotary wing systems, such as helicopters and wind turbines, face challenges in maintaining lift due to blade stall, which is exacerbated by increased pitch angles leading to air current separation, and existing solutions like plasma actuators require frequency adjustments based on air speed and direction.
Innovation Solution
A flow control method that sets a characteristic frequency ratio between the plasma actuator driving frequency and the angle of attack changing frequency, allowing for controlled voltage application to the plasma actuator to suppress stall and improve lift recovery, independent of air speed and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pitch angle of the blade is increased to increase lift coefficient, then the lift coefficient is improved, but the air current separates from the blade causing stall
Solution Approach 1:
The plasma actuator applies a preliminary action by generating plasma and shock waves at the blade front edge before the air current can separate and cause stall. This preliminary disturbance to the flow field prevents the harmful separation effect from occurring in the first place.
Solution Approach 2:
The invention converts the harmful effect of increased pitch angle (which causes stall) into a beneficial effect by using the resulting flow disturbance and pressure changes to generate plasma that actually prevents stall. The harmful stall condition is transformed into the trigger mechanism for beneficial plasma generation.
2Reliability
If the actuator driving frequency is adjusted according to air speed and direction, then the stall suppression is improved, but the control complexity increases
Solution Approach 1:
The system uses the blade's own rotational motion and the resulting flow field characteristics to automatically determine the optimal actuator driving frequency. The frequency is derived from the blade's angle of attack changing frequency, making the system self-regulating without external control complexity.
Solution Approach 2:
The invention changes the parameter approach from adjusting frequency based on external air speed and direction to adjusting frequency based on the blade's intrinsic angle of attack changing frequency. This parameter substitution simplifies control while maintaining effectiveness.
3Reliability
If a changing voltage is intermittently applied to the plasma actuator, then the stall is suppressed, but the power supply complexity increases
Solution Approach 1:
The power supply applies voltage to the plasma actuator in a periodic intermittent manner synchronized with the blade's rotation and angle of attack changes. This periodic action pattern simplifies the power supply control compared to continuous or arbitrarily intermittent voltage application.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively suppresses blade stall and improves lift recovery by determining a characteristic frequency ratio for the plasma actuator, allowing for easy frequency setting and reduced power supply complexity, enhancing lift coefficients and reducing stall duration.
Implementation Method 1
The plasma actuator is a device that generates plasma by applying to an electrode pair a voltage that changes with time
Implementation Method 2
air flow is induced or shock waves are generated in the vicinity of the front edge of the blade
Data Source
AI summary
A flow control method is a flow control method of controlling flow around a blade of a rotary wing, a plasma actuator being disposed at the blade. The flow control method includes: determining a characteristic frequency ratio that is a characteristic value among frequency ratios, each of the frequency ratios being a ratio between an actuator driving frequency and an angle of attack changing frequency, the actuator driving frequency being a frequency of an applied voltage applied to the plasma actuator, the angle of attack changing frequency being a frequency at which an angle of attack of the blade changes in accordance with a rotation angle of the blade; setting the actuator driving frequency such that the frequency ratio becomes the characteristic frequency ratio; and applying a voltage of the set actuator driving frequency to the plasma actuator to control the flow around the blade.