INTA plans to spur business growth by providing some of the world’s most advanced jet engine testing services based on LMS Test.Lab
Testing next-generation jet engines is a high-stakes business. In the rarified atmosphere of this competitive market, only a handful of companies worldwide have the facilities, equipment and know-how to provide such leading-edge testing services for the limited number of manufacturers developing these advanced engines. Testing programs are some of the most demanding of any industry, with contracts won or lost based on the ability to safely, rapidly and reliably perform highly specialized rigorous experiments and handle the massive amounts of output data from strain gauges, dynamic pressure transducers, tachometers, accelerometers, microphones, and other sensors. Hundreds of millions of Euros hang in the balance for the manufacturer and the testing company when sensitive, expensive prototypes expelling over 100,000 pounds of controlled explosive thrust are pushed to the limit with never-before-used materials, turbine blade geometries, nozzle shapes and other innovations. Speed and reliability are absolute necessities in performing these tests efficiently, closely monitoring engine behavior to avoid damage, while post-processing results quickly. Based on these, engineers study product performance and make necessary design changes to get next-generation engines into the air on schedule.
To meet these challenging demands, INTA - the National Institute for Aerospace Technology headquartered outside Madrid, Spain - decided to strengthen its leadership position by replacing its outdated analog test system with a new LMS Test.Lab system based on digital technology. INTA relied upon LMS and Alava Ingenieros, one of the leading engineering service providers in Spain, to integrate and deploy the solution, train the user community, and support INTA in the daily use of the system.
As one of only a handful of facilities in this highly competitive market, INTA built up a thorough experience cooperating with major players in the aerospace industry such as Rolls Royce and General Electric, as well as participating in research programs of the European Union for next-generation experimental engines. Many of the world’s most knowledgeable researchers and engineers in aircraft engine testing work at INTA’s turbojet engine testing center: one of the most advanced aerospace testing installations in the world accommodating engines with up to 140,000 pounds of thrust.
Testing blind with the old analog system
Numerous limitations of their former test system prompted INTA to make the switch. “Our previous system couldn’t keep up with the greater requirements of engine testing now and what we expect to need in the future, mainly because it was based on analog technology which is fast becoming obsolete” says Victor Archilla Prat, Manager of INTA’s Measurement and Instrumentation Group.
Victor Archilla Prat explains that the old analog system provided no immediate feedback on tests as they are being run. Raw data was recorded on reels of magnetic tapes that engineers had to carry back and replay completely to study and analyze the results. “It was like testing blind,” he notes. “We had no way of knowing during the experiments that the engine or the test system itself might be at risk of damage. Also, there was no immediate indication where output data might require detailed study when engine behavior was not as expected. This made testing more risky and added to the time and work needed to interpret test results.”
Analog tapes presented other problems as well. They only were able to record for a few hours, so reels had to be changed as a test was being run, often leaving several-minute gaps in the data. The number of channels that could be recorded simultaneously was limited, as was the bandwidth on each channel and the number of different sensors that could be used. Also, tapes tend to degrade over time, making it difficult to save the data for a period of years as aircraft companies and researchers usually require. Moreover, the analog recording process itself was often not as accurate as engineers would like, with background noise sometimes interfering with signals and tests needing to be re-run. Tests also required a long time to set up, with technicians having to make numerous manual adjustments.
Even given these constraints, INTA still delivered top-notch testing services conducted by its highly experienced staff and for years has earned a highly regarded reputation in the industry. But clearly, the analog system they were working with was not able to keep up with the growing demands of increasingly complex tests requiring ever-faster turnarounds and closer monitoring.
Business value of digital technology
To overcome these limitations, INTA installed a more advanced digital system based on the LMS Test.Lab software and the LMS SCADAS III data acquisition system. Dynamic measurements are made with a high dynamic range up to 24 bits and bandwidths up to 80 kHz per channel for simultaneous signals from multiple types of sensors and transducers. The system provides for continuous, uninterrupted recording and analysis of data even for long-running tests that last for 8 hours or more.
The 136-channel testing and monitoring system is composed of three subsystems. An acquisition and recording front-end subsystem has three LMS SCADAS III units with 128 dynamic channels and eight tachometers controlled by the LMS Test.Lab software. A tracking subsystem running on-line in real time has a single SCADAS III system with 24 input channels and 64 output channels. A storage and analysis subsystem is based on LMS CADA-X Time Data Processing software.
According to Victor Archilla Prat, INTA developed advanced technical specifications for the new dynamic measurement system and opened a public contest. The contract was awarded to LMS because of the state-of-the art digital technology it provides and their extensive background in noise and vibration testing and analysis. Alava Ingenieros supported LMS locally to integrate the complete system. The strong combination of LMS and Alava Ingenieros guarantees further support services for training, applications assistance, and custom programming. LMS developed special tracking software, for example, that include matrix-wise on-line processing and visualization routines. These routines enable the system to analyze and display frequency and amplitude data on selected channels, enabling customer engineers in an adjacent control room to monitor critical output in real time on the display screen instantly as the test is being run. This way, engineers can determine right away if the test is going as expected and pinpoint potential problem areas where they might want to evaluate more in-depth later.
Avoiding damage to expensive engine prototypes
The matrix-wise output is also connected to alarms in the control room that are automatically triggered when safety limit thresholds specified by the engine manufacturer are approached or exceeded. The system then automatically goes through an abort-test procedure that safely shuts down the experiment. “This automatic alarm capability is a significant benefit for avoiding damage to expensive engine prototypes as well as the test system itself,” says Victor Archilla Prat. He explains that many of these development engines are expensive one-of-a kind prototypes that risk being destroyed if pushed too far beyond their operational boundaries.
On-line and off-line capabilities include time/frequency analysis, order and frequency sections with user-definable bandwidth, and octave sections as well as average spectrum, cross-spectrum and FRF. Powerful time data processing features include time visualization and editing, time domain filtering (s.a. high-pass, low-pass, bandpass, etc.), frequency domain processing, several averaging strategies, mathematical calculations on selected channels and the compilation of frame statistics.
“The LMS Test.Lab system can record as well as analyze huge amounts of data very reliably. The ability to provide this level of accurate detail so quickly for specialized tests to our customers is a definite business value,” Victor Archilla Prat explains. “Engineers have the information they need at their fingertips for gaining insight and perspective on the behavior of the design through every phase of testing, from beginning to end.”
Victor Archilla Prat also cites the increased productivity of LMS Test.Lab. Because the system is digital and has numerous automated features, set-ups for individual tests do not require so many manual adjustments and are therefore faster. Moreover, the workbook-based user interface of LMS Test.Lab guides technicians through the sequence of steps for the set-up and test processes. As a result, testing throughput is greater than is otherwise possible. “This greater testing efficiency means greater customer satisfaction and translates into higher throughput and increased profitability,” Victor Archilla Prat notes.
Leading-edge development projects
The LMS Test.Lab system became fully operational at INTA the first quarter of 2005 and has already been relied upon heavily in work on advanced engine development programs. The first of these projects was the European-funded ANTLE (Affordable Near Term Low Emission) program intended to demonstrate the feasibility of developing a low-cost, quiet three-shaft turbofan engine that produces less carbon dioxide emissions than conventional engines.
In this program, INTA works within the EEFAE (Efficient and Environmentally Friendly Aero Engine) consortium of companies that includes Rolls Royce, Fiat Avio, Volvo Aero, ITP and Goodrich Engine Control Systems. During the test, a huge number of parameters were recorded from sensors including shaft speed tachometers, rotating and static strain gauges, tip clearance probes, dynamic pressure transducers, rumble probes and a variety of accelerometers. Many of these are transmitted to the acquisition system via telemetry equipment. In a span of ten weeks, the LMS dynamic system took part in over 27 different performance tests. Another key program for INTA utilizing LMS Test.Lab is testing associated with the Trent 900 engine being developed by Rolls Royce for the new Airbus 380 - a double-deck, 555-passenger airliner for the long-range market.
Gaining a competitive edge
“As we utilize and work with LMS International in expanding the capabilities of the LMS Test.Lab system, we undoubtedly will continue to strengthen our leadership position in the jet engine testing business by increasing the level of service provided to our valued customers and differentiating ourselves in this competitive market,” emphasizes Victor Archilla Prat. “Throughout the first engine testing programs we performed with the new system, we valued LMS Test.Lab as an advanced, extremely reliable and well-supported solution. Taking this step to digital technology provided by LMS will enable us to provide some of the most advanced vibration and dynamic testing available in the aerospace industry. This will form the basis for taking part in some of the most sophisticated research and development programs in the world for next-generation aircraft engines.”
