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Complete Shear Stress

Measurement Solution

 

DirectShear-2D

$9,147$12,347

DirectShear-2D™ is a dual-axis capacitive wall shear stress sensor, providing direct, vector skin-friction measurements in complex, three-dimensional turbulent flows.

DirectShear-2D is a natural extension of IC2’s original capacitive DirectShear™ sensing system, an industry-first microelectromechanical systems (MEMS) direct wall shear stress sensor.

The 2D, or dual-axis, version of this sensor allows for measurement scientists to obtain point vector measurements of turbulent boundary layers. With its easy-to-use, non-intrusive housing and unprecedented dynamic range, DirectShear-2D sensors provide aerospace engineers with a new tool to improve fundamental understanding of complex, three-dimensional flows and validate computational models, paving the way for the future of efficient aircraft.

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 DirectShear sensors.

Power Supply Included

CSU-2001-PXI

CSU-2001-H2U

SKU: 2D CS Series Category:
Weight 5 lbs
Dimensions 18 × 18 × 12 in
Sensor Model

CS-2110 (+$5,499), CS-2210 (+$5,499)

Form Factor

PXI (+$3,299), H2U (+$6,249)

Cable Length

2 meters (+$349), 5 meters (+$449), 10 meters (+$599)

DirectShear-2D is a dual-axis, instrumentation-grade, robust, high-bandwidth, high-resolution, silicon micromachined differential capacitive wall shear stress sensor for subsonic and transonic applications.

The sensor system enables localized, non-intrusive, vector measurement of mean and fluctuating wall shear stress for characterization of complex boundary-layer flows in ground-test facilities.

The design of next-generation air vehicles with increased efficiency cannot be developed without considerable research on the character and dynamics of unsteady, complex, three-dimensional flows. Specifically, some of the most difficult problems in the design of high-efficiency subsonic aircraft are associated with flow control technologies for viscous drag reduction. Time-resolved measurements of skin friction are needed to quantify the underlying transition and turbulence physics present in three-dimensional flows occurring on various aircraft that lead to increased drag and fuel consumption.

Features

  • Micromachined floating element shear stress sensor
  • Time-resolved, two-dimensional, direct wall shear stress measurements
  • Compact, robust sensor package for flush mounting
  • Optimized Sensor Control Unit for high dynamic range and bandwidth
  • Two sensor models to address different sensitivity/bandwidth applications
  • Ability to measure mean and fluctuating quantities
  • 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

Benefits

  • Direct measurement of wall shear stress — no heat transfer calibration required (change, generalize, no in-situ)
  • Non-intrusive — minimal flow disturbance
  • Simultaneous mean and fluctuating wall shear stress measurements
  • High resolution, dynamic range and bandwidth
  • Highly accurate, quantitative measurements
  • Ability to place in arbitrary flow to measure wall shear stress vectors

Applications

  • Point vector wall shear stress measurements in an arbitrary flow
  • Low-speed wind tunnels
  • Instrumentation-grade skin friction sensing
  • Aerodynamic drag research
  • Detection of flow separation
  • Wind tunnel instrumentation

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
  • 2 sensor models available for different applications (see Specifications table)
ModelShear Stress (Pa)Bandwidth (kHz)Sensitivity (mV/Pa)Resolution (mPa)Element Size
CS-2110501.5300.22mm x 2mm
CS-22103005121mm x 1mm

The following additional components and specifications are recommended for AC and DC testing/calibration with the capacitive sensor control unit:

  • 2 – RG58 coaxial cables 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 Publications

Related Research Projects

Frequently Asked Questions

What is the typical application for DirectShear-2D Sensors?

DirectShear-2D Sensors are typically used in low-speed wind tunnel testing applications that require point vector wall shear stress measurements such as complex, three-dimensional turbulence research and detection of flow separation.

What is the operating temperature range for DirectShear-2D Sensors?
The operating temperature range (continuous) is 0-50°C
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.

Are DirectShear Sensors NIST traceable?
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.
How is the sensor typically mounted to the wall of a test section?

The sensor head may be placed in any known angular orientation with respect to the sensing axes. Angular misalignment during installation can result in increased uncertainty due to cross-axis sensitivity. Installation of the sensor head with the alignment key on the upstream side ensures alignment with the critical sensing axis. 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.

How cautious should I be when handling the sensor?

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 be used to keep the sensor face covered at all times when not in use. Proper sensor cleaning procedures are outlined in the provided User Manual.

Are DirectShear-2D Sensors ITAR or export controlled?

These sensors are not subject to ITAR restrictions and have been classified EAR99 under the Commerce Control List.

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