Description
Split-fiber probes have two parallel nickel films deposited on the same quartz fiber, 200 µm diameter and 3 mm long. The ends are copper- and gold-plated, leaving a 1.25 mm sensing length. The film is protected with a 0.5 µm quartz coating.
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.
Split-fibers are intended for measurement of instantaneous velocity and direction in two-dimensional gas flows. They may replace dual-sensor fiber probes (X-probes) in slowly fluctuating flows, when a high spatial resolution is required, or when the angle of attack exceeds the ±45° acceptance angle for conventional X-array probes.
Configurations
Split-fiber probes are available in three configurations for work in free-stream flows, pipe flows and boundary layers. The standard versions are only for gas applications. The picture on the right shows the dimensions common for the Split-fiber probes.
Mounting: 6 mm dia. probe supports.
Split-fiber film probe, straight (55R55)
Used in free-stream applications. Mounts with the probe axis parallel to the direction of main flow, so that the predominant flow vector attacks in the prong plane and perpendicular to the fiber.
Split-fiber film probe, right angle, parallel (55R56)
Intended for radial operation for example between compressor guide vanes. The sensor is perpendicular to the probe axis. Thus measuring the U-V components. Mounts with the probe axis perpendicular to the main flow and rotated, so that the predominant flow vector is in the prong plane and attacks the fiber under 90°.
Split-fiber film probe, right angle, perpendicular (55R57)
Intended for radial operation for example between compressor guide vanes. The sensor is parallel with the probe axis. Thus measuring the U-W components. Mounts with the probe axis perpendicular to the main flow and rotated, so that the predominant flow vector is in the prong plane and attacks the fiber under 90°.
| Technical Data For Split-fiber Sensors | |
|---|---|
| Thickness of quartz coating | 0.5 µm |
| Medium | Air |
| Sensor material | Platinum-plated tungsten |
| Sensor dimensions | 200 µm dia, 1.25 mm long |
| Sensor resistance R20 (approx.) | 6 Ω |
| Temperature coefficient of resistance (TCR) α 20 (approx.) | 0.40%/°C |
| Max. sensor temperature | 300°C |
| Max. ambient temperature | 150°C |
| Min. velocity | 0.05 m/s * |
| Max. velocity | 350 m/s |
| Frequency limit fmax (CTA mode) |
175 kHz |
* Influence from natural convection up to approx. 0.20 m/s.
