SwRI Jet Propulsion System Support Brochure

About the Cover: Preparing an F-16 Fighting Falcon for an engine test run. Courtesy U.S. Air Force/Tech. Sgt. Ben Bloker

From jet propulsion requirements and facility design, to systems and software development, Southwest Research Institute® (SwRI®) provides experienced and timely jet propulsion systems solutions. For nearly 20 years, SwRI has provided jet engine propulsion services and advice on test and repair facilities to the U.S. Air Force, Army and original equipment manufacturers (OEM. SwRI is a recognized leader in developing innovative solutions and providing independent engineering assessments, including:

SwRI’s success in engine and engine component testing is based on a multidisciplinary systems engineering approach to problem solving. Comprehensive expertise in design, modeling, fabrication and integration enables SwRI to address client needs. SwRI has implemented an ISO 9001:2000 compliant program for all design and manufacturing processes, including engineering analysis tasks and software development efforts.

SwRI developed instrumentation for the thrust frame and adapter kit used to test engines for the Air Force.

Thrust Frames
SwRI engineers designed and fabricated a unique dynamometer test stand configured to accept and measure 250 ft.-lb. to 25,000 ft.-lb. of torque and 80,000 lbs. of thrust at speeds up to 200 rpm.

Noise Suppressors
SwRI engineers have developed plant layouts and design detail options for an engine test facility to evaluate large engine-generator sets fabricated by the client. Exhaust emissions, acoustic noise and ground-borne vibrations from the engine generators were key topics of consideration.

SwRI developed a dynamometer test stand to evaluate high-torque engines.

Automation Software
Implementation of the automated and semi-automated control of a jet engine test evolved from operational and performance tests included in technical manuals. SwRI is adept at developing test software from requirements to acceptance testing and post-delivery software maintenance.

Calibration
Using instrumentation error analysis over normal ambient conditions of the test cell and coordination with engine manufacturers, SwRI instrumentation engineers develop technical data to calibrate intermediate and depot jet engine test cells. Software engineers implement semi-automated calibration software and are knowledgeable in error calculations such as SAE ARP4990 for calculating fuel flow in turbine flowmeters. SwRI also coordinates calibration requirements with various calibration organizations, such as the Air Force Precision Measurement Equipment Laboratory (PMEL), Air Force Metrology and Calibration (AFMETCAL) program and the on-site quality team, including development of Calibration Measurement Requirements Summary (CMRS) documents.

SwRI developed system software for the Air Force that communicates between hardware and software used at engine test cells in the field. This image shows an engine vibration waterfall plot developed with the software.

Throttle Controls
Design considerations for engine throttle controls include redundancy and safety, operator ease of use, alignment, computer interface, and application given the cost drivers. Local closed-loop control of stepper motors are used to achieve ±0.25 degree power lever angle repeatable commandable set points. Ramp rates and safety cutback and shutdown commands also are featured.


Engineers use solid modeling tools to design engine throttle controls.

Test Cell Instrumentation Design
When designing a test cell instrumentation system, SwRI engineers consider control of the engine; measurement of safety, performance and facility parameters; and performance calculations. Safety shutdown and redundant safety parameters, such as engine speeds, engine temperature and fuel flow, provide a safety net to the operator. Engineers also interface with engine buses (such as MIL-STD-1553B) for parameter acquisition and take into account measurement characteristics such as linearity, temperature sensitivity, hysteresis, resolution, shielding and grounds, and National Fire Protection Agency (NFPA) regulations. Design encompasses selection of sensors, data acquisition, data processing, data display/recording equipment, and special interfaces and cabling.

	Photo courtesy of DoD: Engineers consider a variety of factors when designing jet engine test cell instrumentation systems, including engine control, safety and performance.
SwRI engineers develop technical data and software to perform semi-automated calibration of jet engine test cells.

Test Cell Correlation/Certification
SwRI engineers have more than 20 years of experience in performing jet engine test cell correlation, which is required to ensure standardization of all testing facilities that certify serviceable status of the same Type/Model/Series (TMS) turbofan, turboshaft and turbojet engines. The typical reference base is an engine, provided by the OEM, that is baselined for all gas path parameters to meet specification requirements. Running the calibrator, data collection, data analysis and (as required) correction back to baseline is mandated because each facility is unique. SwRI is working on a new method to correlate test cells using an engine cycle model when a test cell undergoes a significant modification of the physical structure or the instrumentation system hardware or software.

Test cell correlation analysis software measures engine efficiency and plots correlation correction paths.

This brochure was published in April 2009. For more information about Jet Propulsion System Support, please contact Susan Zubik, Phone (405) 741-5420, Fax (405) 741-3453, or Kevin Marafioto, Phone (210) 522-4932, Fax (210) 522-2572, Aerospace Electronics and Information Technology Division, Southwest Research Institute, P.O. Drawer 28510, San Antonio, Texas 78228-0510.