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Hot-Wire Constant Voltage Anemometer

Single Channel Hot-Wire Constant Voltage Anemometer (CVA)The Hot-Wire Constant Voltage Anemometer (HW-CVA) is a new type of hot-wire anemometer specifically designed for high-performance flow measurements. It enables the real-time measurement of velocity and temperature fluctuations in air and gases without the need for difficult adjustments to tune its frequency response. Maximum performance is assured with changes in probes, probe supports, and even sensor types. Film and wire sensors can both be operated with similar frequency response without retuning.

The CVA principle of operation allows for an almost constant bandwidth operation even when the flow and sensor conditions are varied. Because of its high frequency response and ultralow noise characteristics, the CVA is especially suitable for turbulent flows with large frequency content and/or low turbulent intensity.

For product information, see the Product Information Sheet. The HW-CVA currently comes in a four-channel configuration, however could be custom-configured with respect to (1) number of channels, (2) form factor, and (3) flight ruggedization. For more information on how the CVA is used in practice, refer to the Technical Note. In addition, several relevant publications listed below describe applications in a variety of flow conditions and facilities around the world.


  • Velocity and turbulence measurement using single or multiple sensors in isothermal and non-isothermal flow
  • Accurate measurement of one, two and three components of velocity
  • Measurement of rapid velocity and temperature fluctuations
  • Measurement of high-speed compressible turbulent flows
  • Measurement of transitional and turbulent boundary layers
  • Measurement of very low turbulence intensities


  • High frequency response (> 450 kHz, no tuning required)
  • Operates with wide variety of commercial probes and geometries
  • In-situ temperature compensation without an auxilliary probe
  • Circuit stability ensured regardless of probe cable length
  • Long probe length (up to 100m) without deterioration of frequency response
  • High-sensitivity, ultra-low noise circuit
  • Virtually unaffected by EMI/RFI, cable capacitance and inductance effects

The HW-CVA has been independently tested and compared in numerous wind tunnel and flight tests in North America and Europe. The HW-CVA performs equally well in laboratory and flight conditions.

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The HW-CVA comes in the following configurations:

  • multi-channel
  • customer-specified form-factor/requirements for flight applications

A multichannel box with several CVA boards can be configured for measurements of several velocity and temperature fluctuations with multi-array probes. The multichannel CVA system is available upon request.

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Relevant Publications

  1. "Control of the dynamic non-linearity in a Constant Voltage Anemometer," 58th Annual Meeting of the Division on Fluid Dynamics, Chicago, IL, Nov. 20-22, 2005.
  2. "Comparative Measurements in Ma=2.54 Flow using Constant-Temperature and Constant-Voltage Anemometry," AIAA Journal 43(5), pp. 1140-1143, 2005.
  3. "Lead-resistance effects in a constant voltage anemometer," Review of Scientific Instruments 75(6), pp.2075-2081, 2004.
  4. "Electronic noise in a constant voltage anemometer," Review of Scientific Instruments 75(5), pp. 1290-1296, 2004.
  5. "Comparative Measurements in Mach 2.54 Flow using Constant-Temperature and Constant Voltage Anemometry," AIAA Paper 2003-1277, January 2003.
  6. "Constant Voltage Anemometer Operated Hot-Wire at Subsonic Speeds over Wide Overheats in Unsteady Flows," Review of Scientific Instruments, Vol. 73, December 2002, pp. 4363-4368.
  7. "Automated Constant Voltage Anemometer for Measurements with Temperature Drifts," Review of Scientific Instruments, vol. 73, pp. 1313-1317, March 2002.
  8. "Constant Voltage Anemometer Practice in Supersonic Flows," AIAA Journal, vol. 39, no. 2, pp. 261-270, Feb. 2001.
  9. "Performance Studies of the Constant Voltage Anemometer in a Mach 2.3 Boundary Layer," 18th International Congress on Instrumentation in Aerospace Simulation Facilities, Toulouse, France, June 14-17, 1999.
  10. "Automated Constant Voltage Anemometer with In-Situ Measurements of Overheat and Time Constant of the Hot-Wire," Review of Scientific Instruments, vol. 70, no. 5, pp. 2384-2386, May 1999.
  11. "Software Corrected Hot-Wire Thermal Lag for the Constant Voltage Anemometer Featuring a Constant Bandwidth at the Selected Compensation Setting," Review of Scientific Instruments, vol. 69, no. 9, pp. 3223-3231, Sept. 1998.
  12. "Transfer Function Analysis of the Constant Voltage Anemometer," Review of Scientific Instruments, vol. 69, no. 6, pp. 2385-2391, June 1998.
  13. "Analysis of a Constant Voltage Anemometer Circuit," IEEE/IMTC Conference, May 1993.
  14. "A New Approach to High Speed Flow Measurements Using Constant Voltage Anemometry," AIAA Paper 92-3957, 1992.

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