Soakback Assessment using LAttice Boltzmann Method and Aerothermal Nodal-network for the Design of the Engine-bay Region

Project Information

SALAMANDER

Grant agreement ID: 785455

DOI

10.3030/785455

Project closed

EC signature date 13 February 2018

Start date 1 March 2018

End date 31 December 2021

Funded under

• SOCIETAL CHALLENGES - Smart, Green And Integrated Transport

Total cost

€ 824 873,75

EU contribution

€ 824 873,75

Coordinated by

ALTRAN TECHNOLOGY & ENGINEERING CENTER
France

Periodic Reporting for period 2 - SALAMANDER (Soakback Assessment using LAttice Boltzmann Method and Aerothermal Nodal-network for the Design of the Engine-bay Region)

Reporting period: 2019-09-01 to 2021-12-31

Summary of the context and overall objectives of the project

The present SALAMANDER project belongs to the Clean Sky 2 programme, and offers cooperation between DASSAULT SYSTEMS, world-leader in LBM solutions (amongst other important activities), and ALTRAN, world-leader in Engineering Solutions and outsourced R&D, through its Expertise Center dedicated to Fluids and Thermal Engineering. Its ultimate target is to produce fluid and solid temperature data in soak-back conditions which will be used by the Topic Leader to achieve TRL 6 for the Turboprop Demonstrator.

The projects deploys in 3 phases:
- First, perform high-accuracy, state-of-the-art LBM simulations, of the full engine.
- Second, develop a reduced-cost, Nodal-network model, for the channel region.
- Finally,combine LBM (accuracy) & Nodal methods (reduced-cost) to assess soak-back at acceptable cost in the TP Demonstrator.

Technical challenges are numerous: Physics (Free Convection/ High Mach numbers); Modelling (LBM/Nodal Network Coupling); Computational capacity (Long-Transient/ Engine Geometry/ 3D Fluid & Solid). The highest levels of numerical expertise are required, especially in the field of CFD.

Eventually, the outcome model delivery will allow the Topic Leader to improve the design of the TurboProp demonstrator as well as future products. Finally, EU industrials and environment shall greatly benefit from this study, thanks to the dissemination of this work.

Achieving high fidelity and accuracy in modelling enables to:
- Reduce test dependency to validate product configurations, and potentially in mid-term reduce the cost of flight tests campaign and the time to market.
- Develop more efficient and reliable systems, make each trade-off easier, and facilitate decisionmaking about design.
- Optimize the thermal management, gain in mass and in consumption.

The initial purposes has been fulfilled, as a full methodology following the base concept could indeed be developed and implemented. When tested against both experimental and more accurate simulations, results were found in good agreement, while significantly reducing the computational resources needed for the simulations (~50%). Finally, the complete process could be applied to the new generation Turboprop demonstrator that Safran Helicopter Engines is developing in the frame of CSJU. This demonstrates that the methodology is functional and could be applied to other engines as well.

Moreover LBM solver is still not considered as the mainstream CFD software among CFD practitioners.
The LBM market represents less than 10% of the complete CFD market, but this proportion is expected to grow strongly in the coming years, notably thanks to the detection of industrial cases where the addedvalue is significant and the growing capacity of fast computation. Besides the turnover associated with the CFD market is expected to triple in the next 10 years. These elements of market also suggest that there will be real opportunities for the new methodologies implemented within the framework of this project.

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

WP1 was dedicated to the management, dissemination, and communication activities. Two publications have been done (ASME 2020, 3AF2020+1) and two others are scheduled (3AF2022 and ASME2022).
In WP2, the consortium studied the engine compartment and produced a first methodology document. It showed that it is necessary to properly simulates the cut-off and that the real nozzle geometry is needed in order to have a realistic core flow.
WP3 studied an engine casing in a detailed test chamber environment, with the realistic cut off conditions for the engine. The previous methodologies have been improved and updated based on these new results. WP3 reached its objectives as the engine bay simulation showed promising results and good agreement with test results. However, the simple assumptions made on engine case parts were not enough.
WP4 has therefore computed both internal and external flows. Internal flow have been modelled and computed with both PowerFlow and PowerTherm.
This model provided the highest level of accuracy that can be achieved by now through numerical simulations and was therefore considered as the reference simulation. WP4 was in very good accordance with test results, but it also induced high computational costs, hence justifying the need for a simplified modelling of the internal core channel of the engine (content of WP5).
In WP5, the consortium developed nodal network for the internal flow and computed the engine bay region coupled to this nodal network. This nodal network methodology worked good on RTM322 engine. Results were consistent with both full LBM computation and experiments.
In WP6, methodologies and best practices of all previous WP have been used to compute soak-back phase of the Tech TP. It proved the application of the hybrid approach to Tech Tp to be much faster than WP5’s, thereby proving its applicability during an industrial development process.
Finally, WP7 summarized all the work done in previous WPs and highlighted the future work that remains to obtain a fully industrial methodology of coupled LBM/NN simulations.

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)

Challenges were numerous to develop this methodology:
- Modeling of the full geometry of two different engines with a high level of details.
- Natural convection driven flows involve complex phenoma, so that specific analysis and modelling had to be investigated.
- Dedicated tools also had to be developed and implemented onto Simulia cloud.

An excellent agreement is found with full LBM results while cutting the CPU requirements in half. A fair agreement is also observed with experimental data, though some local discrepancies remain. Improvement axes have been identified and further work should allow to get even better representativeness.

By predicting the challenging thermal environment in the engine compartment of the new turboprop engine after shutdown, SALAMANDER contributes to the Clean Sky II objective of decreasing environment and social impact of aeronautical sector:
- Improvement of engine installation efficiency
- Securization of reliability predictions
- Provision of a cost-effective, green and enhanced engine subsystems design process

Axial Velocity

Temperature