Active contRol of Turbulence for sUstainable
Summary of the project
The increasing volume of aircraft passengers requires disruptive new concepts to meet the strict environmental requirements needed for a sustainable aviation growth. The most serious concerns are noise and pollutant emissions. ARTURO aims at identifying active-control
strategies for turbulent flows targeted to more efficient and quieter aero engines.
The focus of the project is on efficient sensing and control of relevant flow patterns in turbulent flows. The main hypothesis of the project is that machine-learning tools can take advantage of the large amount of data delivered by state-of-art experiments and simulations and provide computationally-efficient solutions to identify these flow patterns. These techniques will be the core of ARTURO.
ARTURO will develop along two pathways, one focusing on turbulent jet noise and the other one on the active control of convective heat transfer in turbulent boundary layers.
Regarding jet aeroacoustics, we will investigate the relation between large-scale-motions (only recently discovered for jet flows), wavepackets and noise production and propagation. Flow structures responsible for the main noise sources and engine-noise propagation
will be identified in an ad-doc designed jet facility. Sensing tools to detect efficiently these flow features will be identified, as well as actuation tools to perform control actions. We plan to generate forcing in the stagnation chamber and nozzle. We will explore the effects of jet pulsation, acoustic forcing and other mechanisms (for example pulsed microjets) to control the turbulent features and mitigate the radiated acoustic spectrum. The results of ARTURO will lead to effective control of noise propagation and radiation, thus paving the way toward quieter aircraft engines.
Regarding the convective heat transfer in boundary layers, we will leverage our unique know-how in measuring instantaneous heat-transfer maps with infrared thermography. ARTURO will aim to identify sensing strategies for coherent motions relevant to the heat transport in the boundary layers, and actuation mechanisms to control them. Several actuation approaches will be tested to identify solutions with high control authority. The outcome of ARTURO will eventually lead in the future to more efficient heat-transfer control in aircraft engines, thus allowing higher inlet turbine temperature and more efficient engines.
ARTURO in a nutshell
Title: Active contRol of Turbulence for sUstainable aiRcraft propulsiOn
Project Reference: PID2019-109717RB-I00
Goal: the identification of suitable flow sensing and active control strategies for heat transfer and noise control in turbulent flows of relevance for aero engines.
Duration: 36 months (1/6/2020 – 31/05/2023).
Total Budget: 117.370 € (Funded by the Spanish State Research Agency).
Host: Experimental Aerodynamics and Propulsion Lab of Universidad Carlos III de Madrid.
Turbulent flows are relevant in most industrial and aeronautical thermo-fluid-dynamic applications. Turbulence is characterized by chaotic changes of pressure and flow velocity, in contrast to what occurs with a laminar flow, where a fluid flows in parallel layers. Turbulent flows are responsible for the majority of mass, energy and momentum transport (from the transport of oxygen in the atmosphere to climate comfort in a room, see for example Holmes et al. 2012). For this reason, turbulence has received a very relevant scientific and technological interest in recent years by researchers in different disciplines, mainly engineers (especially in the field aeronautics), physicists and mathematicians (see, for example, the monograph published by Pope, 2000). Understanding the dynamics of these flows is of paramount importance to improve the performance of countless devices and processes in terms of reduction of energy consumption and environmental impact, as well as in terms of functionality.
When talking about aero-engines thermo-fluid-dynamics, turbulence plays a key role in several critical tasks, including mixing and scalar transport in the burner, heat transfer in the turbine and aero-acoustic noise generation and propagation (Kerrebrock, 1992). The understanding and control of these processes is of fundamental importance for a sustainable aeronautical propulsion. The capability of providing high-performance cooling to the turbine blades is needed to obtain high flow temperature in the turbine, which are necessary to obtain high values of thrust per unit of core mass flow rate and high thermodynamic efficiencies (resulting in reduced fuel consumptions and pollutant emissions). On the other side, controlling noise generation and propagation in the jets issued from modern engines is necessary to reduce the acoustic contamination of near-airport neighborhoods, allowing for a more efficient airport usage with a direct impact also on pollutant emissions (ACI Europe, 2018).
Objectives and roadmap
The main goal of ARTURO is is the identification of suitable flow sensing and active control strategies for heat transfer and noise control in turbulent flows of relevance for aero engines. This long-term goal requires reaching three main objectives:
- Development of pattern-recognition tools for the identification of relevant features in boundary-layer heat transfer and jet aeroacoustic problem;
- Identification of suitable flow sensing tools for these relevant flow patterns;
- The selection of control devices with sufficient control authority.
The methodology of ARTURO builds onto four pillars:
- Design of machine-learning algorithms for pattern identification and sensing.
- Design of experimental facility for active flow control in turbulent boundary layer.
- Design of jet-noise experimental facility with flow control.
- Applications of machine-learning methods to flow-control experiments.