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Hot-Film Constant Voltage Anemometer

Ruggedized 16 Channel Hot-Film Constant Voltage Anemometer (CVA)The multi-channel Hot-Film Constant Voltage Anemometer (HF-CVA) was developed specifically for making simultaneous shear stress measurements using hot-film sensors. As with the HW-CVA, the HF-CVA eliminates problems associated with the use of conventional anemometry, i.e. constant current anemometer (CCA) and constant temperature anemometer (CTA), in wind tunnel facilities. Some of these problems are electromagnetic (EMI) and radio frequency (RFI) interference resulting in a low signal-to-noise ratio (SNR), the need to use precise-length shielded cables, and the need to tweak the instrument for every new flow condition.

The HF-CVA solves these technical issues, while substantially improving the performance:

  • higher sensitivity
  • large bandwidth (30kHz)
  • virtual immunity to EMI/RFI
  • no critical adjustments at each flow condition
  • cable lengths and type not a significant issue

Here are a few applications of the HF-CVA:

  • measuring shear stress
  • mass flow rate
  • flow diagnostics
    • flow stagnation and reattachment
    • boundary layer transition and separation
    • shock boundary layer interactions

The HF-CVA has been successfully tested in numerous wind and water tunnel facilities, flight tests and underwater tests in the ocean. The HF-CVA has also been tested at all speeds from subsonic to transonic to supersonic. The HF-CVA has performed equally well in laboratory and operational conditions (flight and ocean). See this page for a listing of specific facilities where the system has been tested.


The HF-CVA could be custom-configured with respect to (1) channel count, (2) form-factor and (3) flight ruggedization. Please contact us for more details.

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Relevant Publications

  1. "Demonstration of skin friction measurements featuring in situ estimation of conduction loss using constant voltage anemometers and surface hot-films," Review of Scientific Instruments, Vol. 76, Num. 5, 2005.
  2. "Real-Time Unsteady Loads Measurements Using Hot-Film Sensors." NASA TM-2004-212854, Aug. 2004.
  3. "Real-Time Unsteady Loads Measurements Using Hot-Film Sensors." AIAA Paper 2004-5371, 22nd AIAA Applied Aerodynamics Conference, Providence, RI, Aug. 2004.
  4. "Real-Time Extraction of Hydrodynamic Flow Characteristics Using Surface Signatures," Proc. International Symposium on Unmanned Untethered Submersible Technology (UUST03), Durham, NH, 2003.
  5. "Phenomena-based Real-time Aerodynamic Measurement (PRAM) System for Aircraft Performance, Safety, and Control." IEEE Aerospace Conference, Big Sky, MT, March 2003.
  6. Detection of Transition and Flow Bifurcation Regions on a Hydrofoil Using Hot-Film Constant Voltage Anemometry, Proc. Intl. Symposium on Seawater Drag Reduction, Newport, RI, July 1998.
  7. "Flight Demonstration of a Shock Sensor Using Constant Voltage Hot-Film Anemometry." NASA TM 4806, Aug. 1997.
  8. "Analysis of a Constant Voltage Anemometer Circuit." IEEE/IMTC Conference, May 1993.
  9. "A New Approach to High Speed Flow Measurements Using Constant Voltage Anemometry." AIAA Paper 92-3957, 1992
  10. "In-Flight Detection of Flow Separation, Stagnation, and Transition." 18th ICAS Congress, Beijing, China, 1992.
  11. "In-Flight Detection of Stagnation, Transition and Separation Using Micro-Thin Surface Hot-Films." Society of Flight Test Engineers (SFTE) 22nd Annual Symposium, August 1991.
  12. "Cross-Flow Vortex and Transition Measurements by Use of Multi-Element Hot-Films." AIAA Paper 91-0166, 29th Aerospace Sciences Meeting, Reno, NV, 1991.
  13. "Measurement of Crossflow Vortices, Attachment-Line Flow, and Transition Using Micro-Thin Hot-Films." AIAA 90-1636, 1990.
  14. "Simultaneous Detection of Separation and Transition in Surface Shear Layers. Fluid Dynamics of Three Dimensional Turbulent Shear Flows." AGARD CP-438.
  15. "A Unique Technique to Study Laminar Separation Bubble Characteristics on an Airfoil." AIAA Paper 87-1271, 1987.

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