The aim of the CA3ViAR project is the design of an Open-Test-Case Low-speed Fan geometry that will develop instability mechanisms which are representative for UHBR fans of civil aircrafts and perform extensive experimental tests to measure aerodynamic, aeroelastic and aero-acoustic performance in a wide range of operational conditions.

Driven by economic as well as ecological requirements, airplane operators and thus manufacturers invest continuously in reducing the fuel consumption.

Regarding the engines, a way to further reduce the fuel consumption is the increase of propulsive efficiency, which directly depends on the difference between engine exit velocity and flight velocity. This led to the development of Ultra High Bypass Ratio (UHBR) engines equipped with larger fans having a reduced pressure ratio as well as reduced speed.

Such new propulsors, equipped with larger fans, do come with significant challenges from aerodynamic and structural perspective. The higher engine-BPR does increase the required operating range of the fan by moving especially Take-Off and Approach closer to the part power limit of the fan and therefore reducing its stall-margin and increasing the flutter risk. In parallel, the increased fan diameter is driving the intake design, with significant implications on drag and airflow inlet distortion at the Aerodynamic Interface Plan (AIP) during off-design and cross-wind. Beside these increased aerodynamic requirements, the fan itself has to be reduced in weight, leading to application of lighter and stiffer materials, such as Carbon Fibre Reinforced Polymers (CFRP) instead of more conventional titanium alloys, providing more design degrees of freedom in terms of “customized” stiffness and inertia distributions along the blade-span. This implies the need of developing more reliable and accurate methods for aerodynamic, aeroacoustic and aeroelastic design of engine fans.

The main aim of the CA3ViAR project is to design an Open-Test-Case Fan geometry that experiences instability mechanisms which are representative for UHBR fans of civil aircrafts, and to perform a comprehensive experimental investigation to measure aerodynamic, aeroelastic and aero-acoustic performance in a wide range of operational conditions.

Experimental tests will be performed in the Propulsion-Test-Facility (PTF) of the Institut für Flugantriebe und Strömungsmachinen (IFAS) of Braunschweig, Germany.

The CA3ViAR project, coordinated by IBK, is targeting several objectives. As a first step a literature review of the main issues affecting composite UHBR engine fans is performed by the Technische Universität Braunschweig (TUBS). The design of the Low-Transonic Fan (LTF) is led by TUBS with support from DREAM (an Italian SME) in terms of aerodynamic shaping as well as from Leibniz Universität Hannover (LUH) and IBK in terms of aeroelasticity and aeroacoustics.

The LTF test article, to be mechanically designed by IBK, is being conceived in a way to experience aerodynamic and aeroelastic instabilities in an expected way during wind tunnel operations. The supervision of manufacturing-related activities is in charge of IBK through the placement of subcontract(s) to well-recognized manufacturer(s) specialized in rotor blades and parts made of composite and metallic materials, while requirements for the test article integration are provided by TUBS, responsible of WT instrumentation and operations. The execution of the experimental tests aimed at measuring fan instabilities (e.g. stall, flutter, etc.) is performed by TUBS with support from LUH.

The last technical phase of the project is the calibration and the eventual validation of aerodynamic, aeroelastic and aeroacoustic models according to WT test data acquired in the PTF. This last technical phase is led by LUH, with a strong support from all the other partners.

PTF cross-section, cross-wind concept and fan mock-up in the test section (courtesy of TUBS)


The following partners contribute to CA3ViAR:

  • IBK Innovation  Project Coordination support to LSF aeroelastic design, test article design Leader and manufacture responsible
  • Technische Universität Braunschweig (TUBS)  requirements management, LSF aerodynamic design and scaling approach, rig modification and instrumentation, management of WT tests
  • Leibniz Universität Hannover (LUH)  LSF aeroelastic and aeroacoustic design, support to WT test measurements, pre/ post-test predictions
  • DREAM Innovation srl  Support to LSF design and post-test predictions (CFD)

The project started on September 2019, and has a duration of 48 months.

This project has received funding from the Clean Sky 2 Joint Undertaking (JU) under grant agreement No 864256. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and the Clean Sky 2 JU members other than the Union.