Description
Gold-plated wire probes have 5 µm diameter, 3 mm long platinum-plated tungsten wire sensors. The wire ends are copper- and gold-plated to a thickness of 15 to 20 µm, leaving an active sensor, 1.25 mm, on the middle of the wire.
The sensors are arranged in X-arrays, where they form an angle of 90° with one another. The probe body is a 2.3 mm diameter ceramic tube, equipped with gold-plated connector pins that connect to the probe supports by means of plug-and-socket arrangements. Dual-sensor probes have marks (one and two dots) that indicate the sensor number.
The Dual-sensor probes are designed for use in two-dimensional high-turbulence flows. The plating of the ends serves the dual purpose of accurately defining the sensing length and reducing the amount of heat dissipated by the prongs. This results in a much more uniform temperature along the wire than is the case for miniature wires. Another advantage is less flow interference from the prongs at the point of measurement due to the wider prong spacing. Both increase the accuracy at high turbulence levels. All X-probes measure two velocity components simultaneously in turbulent, instationary two-dimensional flow fields. They provide information for calculation of Reynolds shear stress. The flow vector may not exceed ±45°.
Configurations
Dual-sensor gold-plated wire probes are available in four configurations. The picture on the right shows the dimensions common for the probes.
Mounting: 6 mm dia. probe supports.
Gold-plated X wire probe, straight (55P51)
X-probe with straight prongs and with the sensor plane parallel to probe axis.
This probe is used in free-stream applications. Mounts with the probe axis parallel to the direction of main flow, so that the predominant flow vector attacks the two wires under 45°.
Gold-plated X wire probe, cross flow (55P52)
X-probe with straight prongs and with the sensor plane perpendicular to probe axis, for radial operation.
Used in places not readily accessible, for example in pipes. Mounts with the probe axis perpendicular to the main flow and with the predominant flow vector 45° to the two wires.
Gold-plated X wire probe, right angle, parallel (55P53)
X-probe with right-angled prongs and with the sensor plan parallel to probe axis.
Intended for radial operation in pipes or ducts. This probe measure the U-V components. Mounts with the probe axis perpendicular to the main flow and rotated, so that the predominant flow vector attacks the two wires under 45°.
Gold-plated X wire probe, right angle, perpendicular (55P54)
X-probe with right-angled prongs and with the sensor plan perpendicular to probe axis.
Intended for radial operation in pipes or ducts. This probe measure the U-W components. Mounts with the probe axis perpendicular to the main flow and rotated, so that the predominant flow vector attacks the two wires under 45°.
| Technical Data For Gold-plated Wire Sensors | |
|---|---|
| Medium | Air |
| Sensor material | Platinum-plated tungsten |
| Sensor dimensions | 5 µm dia, 1.25 mm long The overall wire lenght is 3 mm |
| Sensor resistance R20 (approx.) | 3.5 Ω |
| Temperature coefficient of resistance (TCR) α 20 (approx.) | 0.36%/°C |
| Max. sensor temperature | 300°C |
| Max. ambient temperature | 150°C |
| Max. ambient pressure | Depends on the type of mounting |
| Min. velocity | 0.05 m/s * |
| Max. velocity | 200 m/s |
| Frequency limit fcpo (CCA mode, 0 m/s) |
90 Hz |
| Frequency limit fmax (CTA mode) |
400 kHz |
* Influence from natural convection up to approx. 0.20 m/s.
