Synthetic Jet Generator With Mechanical Amplification
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Solution Overview
Problem
Existing generators of synthetic jets face limitations in controlling the frequency and speed of jets, with restricted applications due to limited displacement by piezoelectric cells, resonant frequency dependencies, and high dead volume, which restricts their use in varying main flow control scenarios.
Innovation Solution
A generator of synthetic jets with a cavity delimited by a fixed and mobile wall, utilizing a piezoelectric rod actuator with mechanical amplification, allowing variable amplitude and frequency control, and a reduced dead volume design to enhance jet speed and control range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a piezoelectric actuator with a membrane is used to generate synthetic jets, then the jet generation mechanism is simple, but the displacement is limited to a few micrometers and the jet speed is restricted
Solution Approach 1:
The invention introduces a mechanical amplification mechanism that converts the small displacement in one dimension (piezoelectric cell contraction) into large displacement in another dimension (membrane deflection). The lever arm mechanism with pivot points creates a mechanical advantage, amplifying the micrometer-scale piezoelectric displacement into millimeter-scale membrane movement, thereby achieving high jet speeds while maintaining simple actuator structure.
Solution Approach 2:
The invention introduces a mechanical amplification mechanism as an intermediary between the piezoelectric actuator and the membrane. This intermediary component (comprising lever arms and pivot points) transforms the limited piezoelectric displacement into amplified membrane deflection, enabling high jet speeds without complicating the overall actuator structure or requiring resonance conditions.
2Productivity
If the membrane is excited at its natural resonant frequency to achieve significant deformation, then the jet amplitude is improved, but the frequency cannot be varied and requires multiple generators
Solution Approach 1:
The invention replaces the static resonant frequency requirement with a dynamic mechanical amplification system. The lever arm mechanism allows the membrane to be driven at any frequency while maintaining large amplitude deflection, as the mechanical advantage is provided by the amplifier rather than resonance. This enables a single generator to adapt to various frequencies and control the main flow under different conditions.
Solution Approach 2:
The invention changes the operating parameters by decoupling the jet amplitude from the resonant frequency condition. The mechanical amplification mechanism allows independent control of frequency and amplitude parameters, enabling the system to operate effectively across a wide frequency range without requiring multiple generators tuned to different resonant frequencies.
3Device complexity
If a large dead volume cavity is used in the actuator, then the structure is simple, but the jet speed is reduced due to pressure attenuation
Solution Approach 1:
The invention changes the cavity volume parameter from large to small, transforming the dead volume from a harmful feature into a manageable component. The small cavity volume reduces pressure attenuation and improves jet speed, while the mechanical amplification mechanism compensates for the reduced cavity size by providing larger membrane deflection, thereby maintaining simple structure while achieving high jet performance.
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
Enables independent control of jet frequency and amplitude, achieving jet speeds close to or exceeding the speed of sound, with reduced overall dimensions and improved efficiency over a wider frequency range, suitable for various fluid flow control applications.
Implementation Method 1
an actuator (6) mechanically linked with the piston and able to drive the piston with an alternating movement having an amplitude and a frequency
Data Source
AI summary
Generator (1) of synthetic jets (2) for a main flow of fluid, comprising a cavity (10) delimited by a fixed wall (13) and a mobile wall. The fixed wall comprises a sleeve (8) and a head (4) provided with an orifice (14) through which the generated jet of fluid (2) is drawn in from and ejected into the main flow of fluid. The mobile wall is opposite the head. The generator comprises a rigid piston (3) including the mobile wall and sliding in a fluid-tight manner in the sleeve (8), and comprises an actuator mechanically linked with the piston and able to drive the piston with an alternating movement having an amplitude and a frequency. The actuator is capable of providing a movement of variable amplitude and frequency, at least the amplitude being variable during the movement. The actuator comprises a mechanism for the mechanical amplification of displacement.