Data Acquisition and Processing

Data acquisition system room

S2MA - wind tunnel control room

Different types of programmes

First level programmes: they process acquisition data. They depend on the type of test, that's why they are specific. We have some basic programmes which can be used for many different tests, in different wind tunnels, but they are very general: Force and/or Pressure measurements. They are rarely used « as is » nowadays due to test increasing complexity.

Post processing programmes using the results of the first level. For example Interpolation, difference between configurations.... These programmes are general, and can be applied to a lot of tests without modifications.

WDF - Wind Tunnel Data Format made to Measure

Users of wind tunnels rely for the interpretation of test results on data provided by the wind tunnel operator. Typically, this data is arranged by computer software on a data carrier in a format that not only allows finding and interpreting the measured data after sophisticated processing but also enables the allocation of the data to the tested aircraft model configuration. A systematic arrangement is of high importance as it facilitates the interpretation by the client considerably.

What is a WDF?

WDF is a standard software interface for data transfer for DNW and ONERA facilities. The main objectives for WDF project are:

• Make one standard software interface for data transfer to clients,
• Make data file platform independent,
• Provide customer with a coherent set of all wind tunnel test results,
• Provide customer with standard structure of output medium.

Standardization of data formats creates the opportunity to provide these users with a common look-and-feel facilitating the comparison of databases between different facilities for aircraft models of comparable signature. Moreover, the result of this standardization for all participating wind tunnels leads to considerable savings in time for both users and operators once the harmonization process has been concluded.

Whom does it concern ?

ONERA Wind Tunnel Division serve many international customers. These companies are typically familiar with data formats of their own national facilities. As the current practice within these concerns is to share databases for mutual design and development activities it is convenient to have common standards for interpretation of data from wind tunnels and other testing facilities as much as possible.

How does it look and work ?

The new wind tunnel data format is netCDF based, fully platform independent and self-describing. The format is ready to adopt many known and also not yet known data sources. Well known limitations of the different existing current formats are overcome, e.g. the number of variables per record.

Customers of ONERA wind tunnel division receive a medium (e.g. CD or DVD) containing always the same data structure: test results, documentation and software tools.

A series of software tools for WDF use are distributed on the medium. There is a WDF viewer for numerical data presentation and conversion of WDF results into files readable by spreadsheet software or Tecplot® or Matlab® software.