Data Acquisition and Processing in a Large Aerodynamic Test Center

Abstract

Today, a data acquisition and processing system in a large aerodynamic test center must fulfil a number of functions, which are enumerated and analyzed here. These functions, along with the expected performance and the particular location of the test center under consideration, dictate the configurations of the best systems and the choice of hardware and software. As an example, the system utilized in the Modane and Le Fauga Centers of ONERA is described. It concerns two continuous and one intermittent wind tunnels at Modane and one low- speed pressurized wind tunnel at Le Fauga, about 600 km distant from Modane. The detailed description of the data acquisition and processing systems of these two centers is presented and discussed. OR the past quarter century, aerodynamic testing facilities have greatly contributed to the advance of the aerospace sciences and techniques. During the same period of time these facilities, which are quite often concentrated in large specialized centers, have evolved as a function of both the test requirements and the new potentials offered by scientific and technical advances. Progress in physics, and particularly in electronics and computers, has greatly in- fluenced the nature and the performance of the data acquisition and computation systems used in such centers. In France, the Office National d'Etudes et de Recherches Aerospatiales, ONERA (National Institute for Aerospace Research) operates several wind tunnels in its two large Aerodynamic Test Centers (Modane and Le Fauga), where new data acquisition and processing equipment will be utilized shortly.The design and implementation of such a costly system has been the result of two simultaneous occurrences: on the one hand the Modane center, with its very large (8-m- diam) sonic SI wind tunnel, operational for over twenty years, its supersonic continuous tunnel S2, its supersonic blowdown tunnel S3, its hypersonic tunnel S4, and its various other facilities, had to have its data acquisition and processing system renewed according to the new concepts; and on the other hand a new center was being built at Le Fauga, in the Toulouse region, some 600 km away from both Modane and Chatillon, the ONERA headquarters, with the construction of a large pressurized subsonic wind tunnel, called Fl. It was felt that this situation offered a unique opportunity to devise a coherent system that should, with possible minor ad- justments, serve efficiently for a number of years. The paper describes this new equipment and shows the successive steps followed for selecting such a new system, without entering into the detail of the various solutions retained for the wind tunnels themselves.