Pneumatic Probes

Contact

Name

Viola Dehe

Phone

work
+49 241 80 99719

Email

E-Mail
 

The institute has a modular system for different pneumatic probes. This system is used to provide the appropriate measurement technology for each application.

In addition, individual probes and probe traversing units can also be developed and built. A calibration at the free jet calibration wind tunnel is also part of the institute's scope of services. In the following you will find an overview of the standardized probes. Further information can be provided on request.

 

5-Hole-Probes

Photo of a 5-hole probe with different views Copyright: © RWTH Aachen | IST Photo of a 5-hole probe with different views

5-hole probes are used for the experimental determination of flow angles and are suitable for the investigation of three-dimensional subsonic flows. The recommended Mach number range is between Ma=0.1 and 0.9 and the two flow angles are measured relative to the head of the probe in a range of +/- 25°. In addition to the Mach number and the flow angles, 5-hole probes can determine the total pressure as well as the static pressure. In addition, a probe can be equipped with a thermocouple for determining the total temperature, so that the flow velocity can also be derived. 5-hole probes are suitable for stationary measurements in wind tunnels as well as in turbomachines.

Calibration

5-hole probes are calibrated at IST in the free jet calibration wind tunnel. For this purpose, a three-dimensional calibration map (Mach number, α, γ) is measured and dimensionless calibration parameters are determined from the pressure data. Using a multi-parameter polynomial approximation, calibration polynomials are calculated for each calibration quantity. Using these calibration polynomials, the measured variables can then be determined by means of the measured pressures (and temperature, if necessary).

Measured variables

  • Total pressure
  • Static pressure
  • Mach number
  • Flow angle (pitch and yaw angle)

The probe can optionally be equipped with a thermocouple, so that in addition to the variables mentioned above, the total and static temperature can also be measured.

 
 

3-Hole-Probes

Photo of a 3-hole probe with different views Copyright: © RWTH Aachen | IST IST Photo of a 3-hole probe with different views

3-hole probes are used for the experimental determination of two-dimensional flow fields and are suitable for the investigation of flows close to walls. The recommended Mach number range, as with the 5-hole probe, is between Ma=0.1 and 0.9. The flow angle is measured relative to the head of the probe in a range of +/- 25° and allows the determination of two-dimensional flow vectors. The small dimensions ensures minimal disturbance of the flow field and allows a high spatial resolution. The probe head has a height of 0.7mm, a width of 2.0mm and a length of 5.0mm.

Calibration

3-hole probes are calibrated at the IST in the free jet calibration wind tunnel. For this purpose, a two-dimensional calibration map (Mach number, α) is measured and dimensionless calibration parameters are determined from the pressure data. Using a multi-parameter polynomial approximation, calibration polynomials are calculated for each calibration quantity. Using these calibration polynomials, the measured variables can then be determined by means of the measured pressures.

Measured variables

  • Total pressure
  • Mach number
  • swivel angle
 
 

Kiel-Head-Probe

Photo of a Kiel-Head-Probe with different views Copyright: © RWTH Aachen | IST Photo of a Kiel-Head-Probe with different views

Kiel-Head probes are characterized by a high degree of angle independence and are therefore particularly suitable for determining total quantities in flows with unknown or strongly varying flow angles. The recommended Mach number range is between Ma=0.1 and 0.9, as with the 5-hole probe, and the diameter of the probe head is 1.6mm.

Calibration

Kiel-Head probes are calibrated at IST in the free jet calibration wind tunnel. Here, the range of angle independence for the respective measured variable (pressure or temperature) is determined. For a total temperature measurement, the recovery factor is also determined. This enables the total temperature to be calculated, since the measured probe temperature does not correspond to the total temperature of the flow due to the flow around the sensing element of the thermocouple which is necessary for the measurement.

Measured variables

  • Total pressure
  • Total temperature (by thermocouple)
  • Optional or as combination version possible