The NASA Langley Research Center (LaRC) Transonic Dynamics Tunnel (TDT) has been operational since 1960, investigating a wide range of aeroelastic and non-aeroelastic phenomena. A dedicated aeroelastic test facility, the TDT is a large, variable-pressure, transonic wind tunnel. To support unique types of aeroelastic and dynamic tests, the TDT possesses a dynamic data acquisition system (DAS) with synchronous scanning of all analog channels. Steady (static) values are simply computed as the mean of any signal. The existing TDT DAS is referred to as the Open Architecture Data Acquisition System (OA-DAS). An effort was initiated to replace OA-DAS in order to increase the scan rate, increase the channel count, increase the reliability, increase user friendliness, and improve upon some features while maintaining synchronous scanning and other unique abilities. This effort has been spearheaded by researchers within the Aeroelasticity Branch (AB) co-located with the TDT; hence, the new data system has been named AB-DAS. The new data system will serve as the primary data system and will substantially increase the scan rate capabilities and analog channel count. This synchronous and dynamic system enables high-channel-count buffet and aeroacoustic tests in addition to the range of other testing done at TDT.
The incremental development of AB-DAS is divided into three phases. Phase I efforts have enabled AB-DAS to serve as a standalone data system for TDT for a specific genre of tests. Phase II efforts will be those that increase capability such that AB-DAS can assume all functionality and replace OA-DAS as the primary tunnel DAS. Phase III efforts will be continued performance enhancements beyond those required to replace OA-DAS.
The hardware components of AB-DAS include the existing tunnel systems; steady pressure systems; signal conditioners; analog- to-digital converters; processing, display, and storage computer systems; Phase II hardware for further capability development; and instrumentation sources. A new storage area network was created for data handling of AB-DAS systems. The current capability of the storage area network is 1 Gbit with CAT V cables, and the future capability will include 10 Gbit with CAT VI cables. The current 1-Gbit network enables rapid transfer of large files since there is no throttling of the network, and it is independent of other DAS communication functions operating on DASnet. The 10 Gbit will enable substantially faster communication for data file expansion capability. Specialized backplane communication protocols include PXIe-MC/PCIe/MXI communication.
An acceptance test has already been completed that enables standalone operation of AB-DAS to acquire high-channel-count, high-scan-rate buffet and/or aeroacoustic data that is dynamic and synchronously acquired. In its current state, AB-DAS can be used for TDT tests that do not require a balance or digital channels. The current version of AB-DAS has been successful in several wind tunnel tests and incorporates many user-friendly features. Some of these features include unique wind-off tare capabilities; a built-in in-situ calibration routine; compatibility with displays, existing facility systems, and postpoint analysis routines; and the ability to broadcast all data quantities to customer systems. The data quality of AB-DAS has been validated through a formal operational readiness review, through the use of calibrated standards, and through parallel testing with the existing tunnel data system.