Hot-wire and Hot-film Probes

image of hot-wire and hot-film probes

Dantec Dynamics offers a complete probe system for use with Constant Temperature Anemometers (CTA). The CTA anemometer is today’s most widely used instrument for measurement and analysis of the micro-structures in turbulent gas and liquid flows.

The CTA probe program comprises a variety of probe types and probe configurations. There is a probe for almost any measurement situation.

General introduction to probe programme

The main probe features are:

  • Fast response – Fluctuations up to 100 kHz or more can be measured
  • High spatial resolution – Eddies down to tenths of a mm can be resolved
  • High dynamic range – Velocities from a few cm/s up to several hundred m/s can be measured with almost constant sensitivity
  • Continuous signal
  • Little disturbance of the flow due to small sensor sizes

The basic working principle makes it possible to determine fluctuations in any parameter in addition to the velocity that influences the heat transfer from the sensor (i.e. density, pressure, temperature, and composition) provided proper means are taken.

Probe construction

In general, a probe consists of the following:

  • Sensor, forming the heating element
  • Sensor supports, carrying the sensor and leading current to it
  • Probe body, carrying the sensor supports
  • Connector, providing electrical connection to the probe support or probe cable

Probes may have one, two or three sensors for use in one-, two- or three-dimensional flows, respectively. Each sensor requires its own anemometer bridge.

The sensor may either be a thin wire suspended between two prongs or a thin metal film deposited on an electrically insulating substrate. Film sensors can be cylindrical (fiber-film probes) or non-cylindrical (film probes). Wire sensors are used in gases and in non-conducting liquids, while film sensors are primarily designed for use in water and other conducting liquids.

The sensor materials are selected to provide maximum flow sensitivity and highest possible mechanical strength with a minimum of thermal inertia. The size of the sensor and its mounting are selected to give minimal disturbance of the flow.

Probe body design

The probe bodies are designed to provide a rigid, aerodynamic mounting of the sensors and sensor supports with a reliable electrical contact to the probe support or to the probe cable.

Probe supports

All plug-in probes are mounted using probe supports. They serve as the electrical connection between the probe and probe cable and provide a mechanical mount for the probe at the same time.

Manufacturer’s responsibility

Dantec Dynamics is responsible for the safety, reliability, and performance of the items described in this catalog only if:

  • The specific environmental conditions correspond to the requirements stated for the specific item in this catalog or on the probe or probe support container
  • Persons authorized by Dantec Dynamics carry out modifications or repairs
  • The items are used in accordance with the recommendations given herein or on the probe or probe support container

More Information

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