Capacitive Shear (CS) Series
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.
CONTROL UNIT REQUIRED FOR OPERATION
Add the following to your quote to power, control, and interface with your sensor.
The DirectShear™ sensor heads are micromachined, floating element devices that enable time-resolved, one-dimensional, direct mean and fluctuating wall shear stress measurements.
DirectShear-Capacitive Sensors are typically used in low-speed wind tunnel testing applications.
The sensor can survive large accelerations, >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.
IC2 currently dynamically calibrates its sensors in an acoustic plane wave tube and is working on a new Mean Shear Facility for improved calibration capabilities. DirectShear sensor calibrations are not NIST traceable because no standard yet exists. Our DirectShear sensor is the first of its kind on the market that makes this measurement. It is in our purview and we have had discussions with NIST about creating a standard.
The sensing element (the front face) is extremely fragile. Any physical contact with the exposed sensing element can cause damage to the sensor. A protective cap is provided for handling purposes and should remain covered at all times when not in use. Proper sensor cleaning procedures are outlined in the provided User Manual.
Capacitive models are specified for 0-50°C
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.
The sensor head should be aligned such that the deflection of the sensing element corresponds to the direction of flow (long axis of the sensing element is in the streamwise direction). While angular misalignment during installation can decrease the overall sensitivity, the reduction in sensitivity is minor at small angles (<15°). Installation of the sensor head with the alignment key on the upstream side ensures that the sensor is properly oriented. The sensor head should be inserted until the surface of the sensor head is flush with the facility wall. Proper design of the sensor installation port will provide repeatable installation depths and alignment via use of the shoulder and alignment key on the sensor head. Please contact IC2 for support with sensor installation.
These sensors are not ITAR items. They are also not subject to the EAR.
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