DynaMic is a miniaturized, flush-mountable aeroacoustic pressure-field microphone designed for through-wall installation applications such as aeroacoustic microphone phased arrays and fluctuating pressure sensing. IC2’s innovative approach enables higher density acoustic arrays, with significantly reduced cost per channel, resulting in higher channel-count arrays comprised of high-bandwidth, high dynamic range, flush-mounted aeroacoustic microphones. Multiple small vents etched through the diaphragm are used to equilibrate the static pressure between the cavity and the test environment, enabling use in vacuum and/or pressurized facilities.
DynaMic’s low cost and high-bandwidth / high-SPL performance makes the sensor an excellent candidate for replacement of precision condenser microphones in aeroacoustic phased-array measurement applications.
The advanced calibration method leverages the reciprocal nature of piezoelectric transduction, using an electrical drive signal to actuate the sensor in reverse and a laser vibrometer to sense the actuated deflection. Through established electromechanical relations, the sensitivity can be found to a high degree of certainty from this deflection measurement. The method is applicable at all frequencies up to and beyond the resonant frequency of the sensor, as actuation drive electronics and modern laser vibrometers are capable of much greater bandwidths (Mills et al., 2020).
Features
- Flush-mount aeroacoustic pressure-field microphone and dynamic pressure sensor
- Accurate, quantified dynamic pressure measurements at frequencies up to 120 kHz
- Reciprocal calibration (magnitude and phase) over the entire measurement bandwidth
- Advanced packaging techniques enable an ultra-smooth sensor (<10 µm variation) to minimize flow disturbances over the measurement surface
- Large dynamic range (>128 dB)
- Preamplifier enables operation of the sensor using commercially available IEPE-enabled data acquisition systems
- -40 to 85°C continuous operating temperature, limited by electronics
Benefits
- Reduced packaged sensor size – higher density acoustic arrays
- Low profile format – flush mounting in reduced-scale model aeroacoustic wind-tunnels
- Dramatically reduced cost per sensor -high channel count arrays
- IEPE capable – eliminates need for specialized external power supplies
- Wafer-level fabrication and underdamped response reduce phase variation between microphones
- Smooth flow-facing surface for sensor, packaging, and array – reduces / eliminates flow disturbances
- Robust sensor construction – can handle moisture and particulates present in the flow
- Aeroacoustic testing specifications – dynamic range, bandwidth, resolution that fully meet aeroacoustic testing requirements
- Increased phase matching – monolithic (wafer-level) fabrication reduces phase variance between microphones
Applications
- Pressure-field microphone
- Dynamic pressure sensing
- Aeroacoustic phased arrays
- Impedance tube measurements
- Boundary layer fluctuating pressure measurements
- In-model fluctuating pressure measurements
- Suitable for vacuum and pressurized wind tunnels
Sensors Housing Details w/ Dimensions
- 3.18 mm (0.125”) diameter, 17 mm (0.67”) long package
- Ultra-smooth sensing surface (<10 µm)
- 0.75 mm (0.030”) diaphragm diameter
- 0.81 mm (0.032”) diameter micro-coaxial cable with SMA connector
- Required installation height: ~25 mm (0.98”) due to cable bend radius
- Exiting the back of the package is a 0.81 mm (0.032”) diameter micro-coaxial cable which may be configured with an SMA connector for connection to an IEPE-enabled data acquisition system or power supply.
- An additional brass part protects the micro-coaxial cable connector on the back of the preamplifier, resulting in a total package length of 17 𝑚𝑚 (0.67”).
- For space-constrained applications that require routing the cable through a model and/or sting, the cable can alternatively be configured with an IPEX MHF-5 micro-coaxial connector and a separate MHF-5 to BNC adapter that can be connected after installation
Power Supply
- Compatible with commercially available IEPE-enabled data acquisition systems.
- The current provided to the preamplifier may be adjusted by the user (typically from 4−20 𝑚𝐴), with higher currents enabling the preamplifier to maintain performance when driving long cables and/or experiencing high-frequency, high-amplitude events.
- Minimizes equipment requirements (and associated procurement and deployment costs) for large array applications, especially when leveraging existing systems or commercially available IEPE-enabled data acquisition systems.
- IC2 offers single and 8-channel IEPE power supplies.
