Stability and Sensitivity Methods for Flow Control and Industrial Design

Project Information

SSeCoID

Grant agreement ID: 955923

DOI

10.3030/955923

Project closed

EC signature date 13 August 2020

Start date 1 January 2021

End date 31 January 2025

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 4 121 912,88

EU contribution

€ 4 121 912,88

Coordinated by

UNIVERSIDAD POLITECNICA DE MADRID
Spain

Periodic Reporting for period 2 - SSeCoID (Stability and Sensitivity Methods for Flow Control and Industrial Design)

Reporting period: 2023-01-01 to 2025-01-31

Summary of the context and overall objectives of the project

SSECOID is facing two of the main problems present in the modern European society. On the one hand, current environmental pressure demands for more efficient, safer, affordable and environmental friendly products. This requirements create new challenges for the industry to improve the current technological designs in order to meet the expectations of the end users. On the second hand, there is a lack of skilled professionals in the field engineering, in particular in topics such as fluid mechanics, computing and aerodynamic. SSECOID has certainly contribute to overcome those problems by researching in the most advanced areas of fluid mechanics, applying this research to the pioneering and most competitive industry of the field, and by developing a specific and industry oriented training for 15 fellows in the most advances techniques of computing and fluid mechanics.
SSECOID has identified four different challenges to advance in the development of more optimized designs: Accuracy of numerical simulations, Data management, Flow stability and Flow Sensitivity, shape optimization and control.

In base of those challenges, a series of objectives were defined:
● Development of new numerical methods and tools better suited for unsteady flows.
● Identification of the features causing unsteadiness, acoustic, flow detachment or lack of performance of current aerodynamic configurations.
● Investigation of control/suppression of unsteady flow through flow control devices.
● Multidisciplinary evaluation of the most promising applications in relevant problems proposed by industry.
● Training of 15 new researchers in the development of most advanced methods for simulation, feature detection, stability and flow control techniques applied to industrial design.
● Dissemination and communication of the project´s results at international level

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

Activities in SSECOID are structured in base of 4 technical work-packages
WP1 focuses on aligning research efforts with industrial challenges through five test cases (TCs):
• TC1: McLaren Racing Ltd addressed aerodynamic simulations on a full Formula 1 car, improving meshing, LES methodologies, and stability analysis.
• TC2: DNS/LES studies examined low-pressure turbine blade flow separation and the effects of harmonic inflow and active control strategies.
• TC3: Inkjet printhead optimization models were developed to enhance droplet uniformity and reduce experimental costs.
• TC4: Boundary layer stability was analyzed, focusing on the effects of surface roughness and waviness on turbulence.
• TC5: Aero-vibro-acoustic interactions in confined flows were optimized for noise and vibration control.

WP2 enhances high-order CFD methods for accurate unsteady flow simulations. Advancements include mesh-free Immersed Boundary Methods (IBM) and adaptive mesh refinement (hrp-AMR) for efficient compressible flow modeling. Improved temporal discretization techniques, such as BDF error indicators and implicit schemes, enhance stability and accuracy. IBM has been applied to multi-element configurations, while adaptive meshing improves turbulence detection. Mode decomposition tools and refined Variational Mode Decomposition (VMD) enhance flow analysis. Stability studies on transonic buffet oscillations provide insights into instability mechanisms. These developments optimize CFD simulations, improving aerodynamic performance and control strategies for industrial applications.

WP3 develops numerical tools to analyze the stability and receptivity of 2D and 3D complex flows, particularly in laminar-turbulent transition scenarios. It investigates boundary layer stability under surface irregularities and detached flow stability. Research includes linear stability analysis of secondary instabilities in crossflow-dominated boundary layers, DNS simulations of discrete roughness effects, and optimization of manufacturing tolerances for laminar flow airfoils. Detached flow studies examine boundary layer separation, transonic buffet instability, and key instability mechanisms like vortex shedding. These advancements enhance understanding of aerodynamic performance, transition mechanisms, and flow control strategies, improving aircraft efficiency and reducing drag.

WP4 focuses on developing tools to analyze flow sensitivity and receptivity to external perturbations, enabling effective flow control strategies. T4.1 studied transonic buffet sensitivity, identifying critical flow regions influencing instability onset. Adjoint-based sensitivity analyses were applied to stall cells and low-frequency breathing modes, offering insights into their origins and potential passive control strategies. T4.2 investigated aerodynamic perturbation effects on structural output, improving numerical stability and analyzing the impact of a smooth surface hump on swept-wing boundary layers, demonstrating its potential for delaying transition. T4.3 focused on flow actuation and shape sensitivity, optimizing actuators and developing frameworks for airfoil design.

The project has made significant strides in advancing scientific knowledge, fostering collaboration, and ensuring compliance with the European Commission's Open Science policy, as outlined in Horizon 2020's Open Access requirements. By the official end date, 33 Open Access publications and proceedings were produced, including 8 peer-reviewed articles in international journals, all of which are Open Access. Of these, 5 were published under Gold Open Access, guaranteeing immediate and unrestricted availability. Additionally, 5 peer-reviewed articles are under review, and 11 are in preparation, bringing the total to 24 peer-reviewed journal articles published in prestigious scientific journals such as Journal of Fluid Mechanics, Nature Physics, Journal of Computational Physics, AIAA Journal, Physics of Fluids, and Journal of Fluids and Structures, among others.

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)

SSECOID has making substantial progress in industrializing high-order numerical simulation methods, enabling efficient and accurate overnight simulations of complex 3D industrial configurations with large detached flow regions. These methods incorporate advanced turbulence models and error estimation techniques, such as mesh refinement (h-adaptation), moving mesh techniques (r-adaptation), and polynomial order refinement (p-adaptation). Additionally, flexible boundary conditions, efficient iterative schemes, parallelization strategies, and mode decomposition algorithms are being implemented to enhance computational efficiency.

SSECOID has also applied stability and adjoint-based approaches to study high-speed flows, high Reynolds number effects, and laminar-to-turbulent transition in unsteady conditions, providing valuable insights into aerodynamic behaviors. In flow control, new tools are developed to optimize the application of passive and active control strategies based on sensitivity maps of unstable flow features. These advancements play a vital role in the design of future aircraft, supporting environmentally sustainable technologies and reinforcing European aerospace leadership in innovation.

High order numerical simulation. Immerse boundary method on a NACA profile at high angle of attack.