invEstigation of pushing pRopeller engine Configurations trough wind tunneL Experiments

Project Information

ERaCLE

Grant agreement ID: 687015

DOI

10.3030/687015

Project closed

EC signature date 4 December 2015

Start date 1 July 2018

End date 31 May 2021

Funded under

• SOCIETAL CHALLENGES - Smart, Green And Integrated Transport

Total cost

€ 1 313 500,00

EU contribution

€ 1 025 575,00

Coordinated by

IBK-INNOVATION GMBH & CO. KG
Germany

Periodic Reporting for period 2 - ERaCLE (invEstigation of pushing pRopeller engine Configurations trough wind tunneL Experiments)

Reporting period: 2019-07-01 to 2021-05-31

Summary of the context and overall objectives of the project

The aim of ERACLE is to investigate Near-field and far-field Acoustic propagation of a pushing and wing mounted propeller-based propulsion.

It is well known that pushing propellers including CROR are critical from an acoustic point of view. Actually, in this context, installation effects play an important role.
Two main types of installation effects can be discerned:
• Aerodynamic installation effects leading to modification of the aerodynamics of the pushing propeller by the aircraft body and wing. Indeed, noise emissions result from the impingement of the turbulent wake shed from the upstream wing and nacelle onto the leading edge of the propeller blades and from the ingestion of turbulence from various sources (atmospheric, wing boundary layer, etc.)
• Acoustic installation effects (noise reflection and refraction on the aircraft).

However, apart from possible drawbacks in terms of acoustic performance, there is one thing in favour of the pusher configuration which needs a better evaluation: a pusher propeller picks up airflow that is already decelerated by the wing and fuselage to generate thrust, while a puller propeller picks up undisturbed air to blow it onto the fuselage and wings, which in turn decelerate the airflow. This difference means that a pusher propeller may be more efficient at higher speeds, with consequent savings in terms of fuel consumption and emissions.

Overall, planned activities are the following:
1. To perform a WT test campaign to measure the near-field and far-field acoustic propagation of a pushing and wing mounted propeller-based propulsion, parameterized w.r.t. propeller design features, installation configurations, and different kind of aerodynamic flows generated by the wing through controlled boundary layers;
2. To collect and post-process WT test data;
3. To further develop/ validate a fast engineering toolset for the preliminary design of propeller-wing arrangements vs. acoustic performance.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

WT model and test requirements have been extensively discussed with the TM during the first period. Even if with some delay in the first two months due to vacation periods, requirements have been agreed and the geometry of the model delivered by the TM in September 2018. In the same month, Implementation Agreement and Consortium Agreement have been signed and delivered in October 2018 as the first deliverable of the project.
The Dissemination and Exploitation plan, Deliverable D1.2 has been prepared by IBK and submitted in December 2018.
The preliminary design of the model has been completed by ERACLE and the PDR achieved in March 2018.
The detail design of the model is ongoing and will be released at the CDR. In particular, the situation at the end of the first period is that the design is almost complete: main wing, nacelles with integration of motor and cooling system, hubs and propellers, interface with the WT are ready and going to be reviewed with TM, WT and JU. Some design details regarding the integration of some auxiliary systems, such as the blowing system and related parts, the motor driving & synchro system and the integration of related subsystems, are still in the definition phase.
To check the effectiveness of the electrical motor cooling system, a demonstrator has been designed, manufactured and tested in the ENEA WT. The test has been successfully performed, giving positive results in terms of system capabilities to ensure the correct venting and cooling of the electrical engines. The test report is ready, and the design features have been implemented in the WT model design.
The preliminary design of the remaining systems is mostly completed, the only open points regard the effective capability to comply with the requirements in terms of performance of
- The motor driving & synchro system to precisely control the relative rotation phase of propellers;
- The blowing system to effectively control the boundary layer thickness with a reasonable flow uniformity in the spanwise direction.
The test matrix has been prepared and agreed with TM and WT. In particular, the WT test campaign has been successfully negotiated, and the contract with Pininfarina (PF) prepared and signed.
Regarding the development of the fast tool to predict the aeroacoustic performance of pushing propellers, a huge effort has been made to develop a first preliminary version of the tool, still in the tuning phase. Indeed, to develop a first version of the tool, a test campaign with isolated propellers (COTS for commercial UAVs) has been performed by UR3 in the anechoic chamber in Rome. The first database for the prototype tool is ready.
All the design and analysis activities, performed by IBK, NHOE and UR3 during the first period, gained benefit from the precious suggestions and manufacture feasibility analysis provided by ERF.
Objectives as stated in the Annex 1 of the GA are almost achieved or going to be achieved. For details please refer to section 1.1.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Pushing propellers, potentially more efficient than pulling ones at high speed, are potentially noisier. Therefore, further efforts are required to reduce the environmental impact of pushing propellers in terms of noise reduction, to allow for a more diffused adoption of such a more promising propulsion configuration.
Implementing low fuel consumption and low-noise technologies into new aircraft will be crucial for economic success. The implementation and the success of this project is in fact contributing to the development of European technical leadership in aircraft manufacturing, increasing competitiveness of EU companies on a worldwide market by helping in the realization of more efficient and less expensive aircraft. By further reducing noise and identifying innovative noise reduction solutions, the project will in fact make a significant contribution towards the major social objectives of the European Community. Moreover, the ERACLE project addressing the environmental aspects of noise and air quality, is indirectly contributing to meeting societal needs for mobility. It helps to increase the acceptance of such mobility impacts in local communities in the proximity of airports.

Concerning exploitable results, the solutions of ERACLE to develop predictive fast tools through metamodels have a huge exploitation potential, especially for improving the efficiency of the preliminary design process of next generation aircraft. Indeed, UR3, IBK and NHOE are already discussing with ADS a possible activity continuation in close cooperation with ADS, and beyond the ERACLE project, accounting for effects not in the scope of ERACLE.
Apart from this, IBK and NHOE are strengthening their visibility in the landscape of WT model and system manufacturers, with the experience with a new WT service supplier (PF).
Furthermore, UR3 are continuously improving their capability on aeroacoustic simulation in industrial environments and increasing their visibility with airplane manufacturers (TM).

3D CAD of ERACLE WT model