Multi-hole probes are fluid mechanics instruments designed to determine the flow velocity and pressure through direct measurement of the pressures at the probe tip. The probes are calibrated at multiple flow angles in an airstream of constant speed. In an unknown test flow, the measured port pressures are compared to the calibration map by sophisticated pressure-to-velocity reduction software, which returns the total and static pressures at the probe tip, as well as the flow angles. Using thermodynamic data (reference pressure and total temperature) provided by the user, the velocity vector, as well as the total and static pressure at the measurement location may be determined.

There are four basic elements required for flow measurement using a multi-hole Aeroprobe:

1. The probe itself. Aeroprobe provides many probe options, with various geometries and capabilities.
2. An accurate probe calibration, or multiple probe calibrations, as required to properly cover the expected speed range of the probe. For over 10 years, Aeroprobe has been providing accurate, robust probe calibrations supported by data from precise pressure sensors with NIST-traceable calibrations.
3. The data acquisition hardware and software required to measure the probe port pressures in the test flow. Our AeroAcquire data acquisition software provides an integrated environment for multi-hole probe positioning, pressure data acquisition, pressure-to-velocity reduction (through the integration of Multiprobe™) and data storage.
4. A reduction algorithm to convert the measured port pressures to velocity components based on the calibration map. Our Multiprobe™ is the most advanced commercially-available multi-hole probe pressure-to-velocity reduction software.

There are several additional components that contribute to the usefulness of the Aeroprobes and the data resulting from their use:

1. An automated traversing system to position the probe (or multiple probes in a rake) within the test environment. All full traversing system typically consists of:
   • Motor Controller (AP3KM, AP4KM)
   • Stepper Motors
   • Motor Encoders for Positional Feedback (AP4KM Controller Option)
   • Traversing Scales (1D, 2D or 3D Configurations)
   • Probe Mounts, Mounting Rods and Sleeves
2. Scientific visualization software for the graphing and analysis of the three-dimensional velocity data generated through use of the Aeroprobes. AeroAcquire exports data to Tecplot (by AmTec) for visualization.
3. For fast-response probes, it is crucial that the pneumatic system between the tip of the probe and the sensors be calibrated for the attenuation/amplification and phase change of pressure waves as a function of frequency. Aeroprobe has experience in both generating and employing these calibrations within the scope of probe data acquisition and data reduction, through the use of the Acoustic Recovery (ARC) software. It is possible to apply this technique to conventional systems as well, effectively increasing the available bandwidth of the system.

Typical systems are described on our website. However, we are accustomed to accommodating requests from customers for customized probes and systems that will better suit their applications. If you don't see a probe or system option or capability that you require, please do not hesitate to ask Aeroprobe personnel about a custom system.