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DirectShear – Optical | Sensor Head
DirectShear-Optical™ sensors are robust, high-bandwidth shear stress sensors designed from the ground up for harsh environments, including high-temperature applications. The sensors employ purely optical transduction, a silicon/Pyrex micromachined floating element, and a remote optical fiber readout to enable time-resolved one-dimensional, direct shear stress measurements at high temperatures.
Like the original DirectShear line of sensors, IC2’s DirectShear-Optical sensors are capable of both mean and dynamic measurements of wall shear stress over a wide dynamic range and are offered in a range of sensor models to suit different applications.
The optical sensors are now commercially available and are ideal for precision skin friction measurements in high-speed, high-temperature test facilities. Click here to see how NASA is utilizing these sensors.
|Optical Sensor Model||
OS-0110, OS-0210, OS-0310, OS-0410, OS-0510, OS-0610
Designed from the ground up for harsh environments, including high-temperature applications
- Optical micromachined floating element sensor for time-resolved, one-dimensional, direct shear stress measurements in harsh environments
- Optical gratings for direct transduction of shear stress with remote optical fiber readout
- Silicon/Pyrex sensor structure for high-temperature environments (up to 400°C continuous)
- Optimized Sensor Control Unit (SCU) for high dynamic range and bandwidth
- Suite of sensor models for different applications
- Mean and fluctuating optical sensor measurements compatible with all DirectShear CS Series models
- Selectable low-noise AC or rechargeable Li-ion battery power source
- Optimized high dynamic range and bandwidth
- System status and battery voltage LED indicators
- Rugged, industrial LC Duplex fiber connection
- Removable shielded sensor cable
- Time-resolved, direct mean and fluctuating wall shear stress measurements
- Differential optical shear stress sensors for subsonic and transonic applications
- Instrumentation-grade skin friction sensing in high temperatures and harsh environments
- Aerodynamic drag research
- Detection of flow separation
- High-speed wind tunnel testing
- Direct measurement of shear stress
- Harsh environment capable
- Non-intrusive - minimal flow disturbance
- High resolution, dynamic range and bandwidth
- Immune to EMI
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)
|Model||Shear Stress (Pa)||Bandwidth (kHz)||Sensitivity (mV/Pa)||Resolution (mPa)||Element Size
|OS-0510||10||0.8||190||0.1||1.5mm x 0.7mm|
|OS-0110||50||1.8||40||0.5||1mm x 0.7mm|
|OS-0610||100||2.5||20||1||1mm x 1mm|
|OS-0210||300||5||5||2||0.4mm x 0.4mm|
|OS-0310||1000||10||1.3||50||0.3mm x 0.3mm|
|OS-0410||5000||20||0.3||50||0.3mm x 0.3mm|
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 - Optical Sensors?
What are the operating temperature ranges for DirectShear - Optical sensors?
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.