High-Frequency Reciprocal Transducer Calibration via Electrical Actuation
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Solution Overview
Problem
Conventional high-frequency calibration methods using shock tubes face challenges with nonlinear, high-amplitude pressure fluctuations and require calibrated reference sensors, which are difficult to ensure identical pressures due to spatial variations in pressure from standing waves and other environmental artifacts.
Innovation Solution
A high-frequency reciprocal transducer calibration method involving electrical actuation, where an oscillating voltage is applied to a diaphragm of a reciprocal transducer, correlating the deflection pattern with the voltage to calibrate the transducer, enabling calibration up to several megahertz frequencies without the limitations of pressure-driven methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If shock tubes are used to generate high-frequency pressure waves for calibration, then high-frequency calibration capability is achieved, but the pressure fluctuations become nonlinear and high-amplitude which are not ideal for low-amplitude sensor applications
Solution Approach 1:
The patent replaces the mechanical shock tube system with an electrical actuation system. A speaker or actuator driven by an oscillating voltage signal generates pressure waves on the diaphragm, substituting the mechanical shock wave generation method with an electrically controlled approach that enables precise amplitude and frequency control while maintaining linearity.
Solution Approach 2:
The patent changes the control parameters from impulse-based mechanical shocks to continuous oscillating voltage signals. By controlling the voltage frequency and amplitude, the system can generate pressure waves at specific frequencies with controlled amplitudes, enabling calibration across a range of frequencies while maintaining linearity and avoiding the nonlinear high-amplitude fluctuations of shock tubes.
2Speed
If conventional shock tube methods are used for calibration, then high-frequency calibration is possible, but a calibrated reference sensor is required which faces the same calibration challenges
Solution Approach 1:
The patent implements a self-calibration approach where the transducer under test is electrically actuated and its response is measured optically. The system uses the known electrical input signal and the optically measured diaphragm displacement to directly determine the transducer's frequency response without requiring an external reference sensor, making the calibration system self-sufficient.
Solution Approach 2:
The patent introduces an optical measurement system as an intermediary to measure diaphragm displacement. This optical intermediary provides a precise, non-contact measurement method that bridges the electrical actuation and the pressure wave generation, enabling accurate characterization of the transducer's response without requiring a reference pressure sensor.
3Measurement precision
If reference sensors are used in shock tube calibration, then calibration can be performed, but ensuring identical pressures at sensor and reference sensor locations is difficult due to spatial variations from standing waves and diffraction
Solution Approach 1:
The patent extracts the pressure measurement function from a separate reference sensor and integrates it directly into the transducer under test by measuring the diaphragm's own displacement. This eliminates the need for a separate reference sensor and the associated problems of spatial pressure variations, as the measurement is taken at the exact location where the pressure acts.
Solution Approach 2:
The patent makes the transducer under test serve multiple functions: it is both the device being calibrated and the measurement sensor. By using the same diaphragm that responds to pressure as the element being measured (through optical displacement measurement), the system eliminates the need for separate reference sensors and ensures that the measurement is taken at the exact location where pressure acts.
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 calibrates reciprocal transducers at higher frequencies, such as those encountered in high-speed vehicles, by correlating electrical actuation with pressure wave reciprocality, providing a more accurate and reliable calibration technique than conventional pressure wave techniques.
Implementation Method 1
coupling a first oscillating voltage with an electrical connector of the reciprocal transducer
Implementation Method 2
directing a source onto a diaphragm of a reciprocal transducer
Data Source
AI summary
A high-frequency dynamic pressure transducer calibration system and method is provided. The method directs a source onto a diaphragm of a dynamic pressure transducer. An oscillating voltage at a target frequency (or range of frequencies) is generated. The oscillating voltage is coupled to an electrical connector of the dynamic pressure transducer. A deflection pattern of the diaphragm is recorded. The dynamic pressure transducer is calibrated by correlating magnitude of the deflection pattern with the oscillating voltage as a function of the target frequency (or range of frequencies).