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DirectShear – Capacitive | Sensor Head
DirectShear™ Sensors are robust, high-bandwidth, high-resolution, micromachined wall shear stress sensors for subsonic and transonic applications. This non-intrusive, design delivers an unprecedented degree of precision and accuracy for both mean and fluctuating wall shear stress measurements. This sensor system greatly extends the spatial and temporal resolution capabilities over existing devices, offering exceptional bandwidth and dynamic range.
Originally developed for NASA, the capacitive sensors are now commercially available and are ideal for precise skin friction measurements in wind tunnels. Click here to see how NASA is utilizing these sensors.
For high-temperature applications, please see our DirectShear™ Optical product line.
|Dimensions||18 × 18 × 12 in|
|Capacitive Sensor Model||
CS-0110, CS-0210, CS-0310, CS-0410, CS-0510, CS-0610
The DirectShear™ sensor heads are micromachined, floating element devices that enable time-resolved, one-dimensional, direct mean and fluctuating wall shear stress measurements.
- Micromachined floating element shear stress sensor that enables time-resolved, one-dimensional, direct shear stress measurements
- Compact, robust sensor package for flush mounting
- Optimized Sensor Control Unit (SCU) for high dynamic range and bandwidth
- Suite of sensor models for different applications
- Originally developed for NASA
- Ability to measure mean and fluctuating quantities using a variety of capacitive devices
- Integrated rechargeable lithium-ion battery system minimizes power line noise
- Multi-pin shielded sensor connector provides supply voltages and carrier signals
- System status and battery voltage LED indicators
- Instrumentation-grade skin friction sensing
- Aerodynamic drag research
- Detection of flow separation
- Wind tunnel instrumentation
- Direct measurement of shear stress — no heat transfer calibration
- Non-intrusive — minimal flow disturbance
- Simultaneous mean and fluctuating shear stress measurements
- High resolution, dynamic range and bandwidth
- Highly accurate, quantitative measurements
Sensor Head Housing Details
- Non-intrusive — backside contacts for minimal flow disturbance
- Standard stainless steel cylindrical housings available with or without shoulder and key alignment and detachable cable
- Multiple sensor head form factors, materials and finishes available to meet installation requirements.
- Custom housings/materials available
- Suite of 6 sensor models available for different applications (see Specifications table)
- Also available in multi-sensor 1x4 array package
|Model||Shear Stress (Pa)||Bandwidth (kHz)||Sensitivity (mV/Pa)||Resolution (mPa)||Element Size
|CS-0510||10||0.75||100||0.1||2mm x 0.5mm|
|CS-0110||50||1.5||40||0.1||2mm x 0.4mm|
|CS-0610||100||2.5||10||1||2mm x 0.4mm|
|CS-0210||300||5||1||1||1mm x 0.2mm|
|CS-0310||1000||10||0.3||5||0.5mm x 0.15mm|
|CS-0410||5000||20||0.08||10||0.5mm x 0.15mm|
The following additional components and specifications are recommended for AC and DC testing/calibration with the capacitive sensor control unit:
- RG58 coaxial cable with BNC connectors
- Data acquisition system (DAQ) – AC/DC measurement
- Sensing Range: ±1, ±5, ±10V – sensor dependent (see datasheet)
- Resolution: 18+ bits
- Sampling frequency:
- Sensor dependent w/ analog filter between sensor output and analog-to-digital converter (ADC)
- 100+ kS/s w/o analog filter
- Digital multimeter – DC measurement only
- 6.5 digits with power line cycle (PLC) integration
- DAQ or PC connection (e.g., GPIB)
Related Research Projects
Frequently Asked Questions
What is the typical application for DirectShear-Capacitive Sensors?
DirectShear-Capacitive Sensors are typically used in low-speed wind tunnel testing applications.
What is the operating temperature range for DirectShear-Capacitive Sensors?
What is the difference between the H2U and PXI control units?
How do acceleration forces affect the sensor?
The sensor can survive large accelerations; more than 200g. The floating element’s small size and mass limit any significant inertial loads. However, accelerations will affect the output of the sensor. To account for acceleration, an additional accelerometer should be placed near the DirectShear sensor and subtract the coherent power between the DirectShear sensor and the accelerometer. IC2 provides the acceleration sensitivity data in the calibration packet included with each sensor purchase. IC2 is currently working on a future generation of the sensor that will compensate for acceleration automatically. Please contact IC2 for additional information regarding acceleration compensation.
Does each sensor need its own control unit?
Yes. Each sensor requires a dedicated control unit and each unit supports a single sensor at a time; however, multiple sensors can be paired with a single control unit in cases where spares or different sensor types are desired. Engineering services are available for customers who desire custom configurations of control units to support multiple sensors.