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Instrumented engine Cradle for the TUrboprop demonstrator ground teSt

Periodic Reporting for period 2 - ICTUS (Instrumented engine Cradle for the TUrboprop demonstrator ground teSt)

Okres sprawozdawczy: 2019-02-01 do 2020-07-31

In the framework of the development of a new turboprop engine demonstrator (WP3 of the ENGine ITD JTP), a full Integrated Power plant System (IPPS) will be ground tested. The objectives of the ICTUS project are:
- To benchmark current turboprop engine installation : the benchmark aims to deliver recommendations/suggestions for an optimize engine installation configurations in line with the ENG ITD objectives (weight savings and performance);

- To design the engine cradle for ground tests: a virtual prototype of the engine cradle is developed to predict the static and dynamic behaviour of the cradle in operational conditions; design is conducted to be compliant with CS23 regulation rules; as the design must be representative of a real installation, the model will be based on the Finite Element Method taking into account for detailed geometry (especially welding connections), static and dynamic loads. A sensitivity analysis (stiffness, damping, interface, boundary conditions) is conducted to identify the most suitable configuration, to validate the engine mounts (frozen configuration). As output, manufacturing drawing are delivered

- To manufacture, to instrument and to qualify by test the engine cradle: a tubular structure is manufactured; an instrumentation setup is proposed and installed on the cradle; the relevant position of the sensors for monitoring purpose is set-up based on SAFRAN HE specifications and numerical results to identify the most critical area; new technology sensors will be studied especially the FBG technology for strain gauges; finally a static and dynamic test campaign is performed to qualify the cradle and the instrumentation and to identify the critical rotating speed of the engines;

- To characterize the engine compartment ventilation system: CFD analysis are conducted to verify the temperature and the air flow exhausted by the engine.
The optimization of a low weight cradle will contribute to the ACARE objectives in providing a more efficient turboprop leading to a reduction of the overall aircraft fuel burn. Designed for flight test conditions, the cradle will accelerate the possibility to introduce such new generation of engine (known to be more eco-friendly than equivalent turbomachinery) on the next generation of aircrafts. Finally, with an accurate design of the anti-vibrating mounts and a complete dynamic analysis of the cradle, the cockpit and cabin comfort will be increased towards noise emission and crew noise exposure.
In a preliminary step, VibraTec has performed a market survey to analyse the state of the art of the Turboprop architectures. Safety requirements and mechanical main failures have been translated in terms of mechanical loads leading to the definition of a flight envelope specification. At least, the Tech-TP test bed environment, located in the SAFRAN facility at Tarnos, has been inspected and qualified.

Starting from these specifications, the second phase of the program has been focused on the design of the cradle. A detailed dynamic model has been developed to predict the static and the dynamic response of the system. The analysis has covered a wide number of configuration including ultimate loads. The critical design review process has been achieved end of 2018, opens the manufacturing process.

With the support of the SACI Industries, the cradle has been manufactured. Instrumented by VibraTec with strain gauges, the cradle has been qualified in the VibraTec laboratory and submitted to representative radial and axial loads. The equipment has been delivered in May 2019 allowing the first TechTP run in June 2019.


Last step of the program has been dedicated to the exploitation of the static engine test. A thermal analysis has been performed using Computation Fluid Dynamics to adjust the calibration process of the sensors, a minimal requirement to accurately monitor the TechTP demonstrator. In parallel, an inverse method has been setup to measure the operational loads of the TechTP engine. Such indirect measurements allows to characterize the static and the dynamic forces transmitted by the engine at its mounting points. While direct methods only gives access to the resulting forces, the proposed indirect method fully characterizes the mechanical impact of the engine on the aircraft, a smart way to specify the engine interface without the cost of flight test. A test campaign has been conducted to deploy the methods. The full operational load characterization of the TechTP has been extracted, analysed and delivered.

The ICTUS program has strongly contributed to the delivery of the first key demonstrator in Cleansky2 with the manufacturing of the cradle. The proposed instrumentation combined to the development of advanced test methods offers major breakthrough to improve the exploitation of static engine test bed. It opens new ways to predict the engine interface within its aircraft environment for both engine and aircraft manufacturers.
Progress beyond the state of the art:
- The proposed measurement process for GVT has never been conducted on a turborprop engine at SAFRAN
- The Cradle has been designed for flight conditions; it supports extreme flight loading cases and reduce the change in the frame of an industrial production
Major impacts are:
- The delivery of the Cradle will allow the ground test of the Tech-TP Cleansky2 demonstrator
- The smart instrumentation will allow for the characterization of the operational loads of the engine independently of the ground test bench effects
Finally, towards the beneficiary, a direct impact is the development of a new service in the manufacturing of aeronautic architecture including for flight specifications in a harsh environment.