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POLlution Know-how and Abatement

Periodic Reporting for period 1 - POLKA (POLlution Know-how and Abatement)

Reporting period: 2019-02-01 to 2021-01-31

POLKA - POLlution Know-how and Abatement

PROBLEM / ISSUE BEING ADDRESSED

Combustion of hydrogen from renewable sources is an emerging technology that can replace fossil fuels and so provide carbon-neutral energy. The goal of POLKA is to solve serious technical problems, which are unique to hydrogen combustion: thermoacoustic instabilities and flashback. Thermoacoustic instabilities are large-amplitude pressure oscillations caused by an escalating interaction between the flame and acoustic waves; they tend to occur unexpectedly and cause major hardware damage. Flashback is the dangerous phenomenon of the flame propagating backwards into components not designed for high temperatures. The ultimate vision of POLKA is to create new physical insight and advanced simulation tools, so as to underpin the development of hydrogen-fuelled combustion systems (gas turbines, aero-engines, boilers furnaces, etc.).
POLKA considers combustion systems that have a continuously burning flame (rather than intermittent combustion as, for example, in a spark-ignition engine); these are found in many applications, in particular: stationary gas turbines for power generation, aero-engines with jet propulsion for transport, boilers to heat homes and other buildings, furnaces for smelting metal or applying high-temperature treatments in the manufacturing industry, rockets to launch satellites.

IMPORTANCE FOR SOCIETY

Environment
Combustion of fossil hydrocarbons releases greenhouse gases, mainly CO2, into the atmosphere. This is a major factor in global warming. Moreover, toxic gases like NOx are produced, which are harmful to human health, ecosystems and agricultural crops. POLKA is developing low-pollution technologies for combustion and noise control.

People
European industry is in urgent need of young engineers with high-level skills in the mechanical sciences. POLKA is educating young researchers to become well-rounded scientists with an analytical and an intuitive side.

Gender equality
POLKA is an engineering network where half of the scientists-in-charge are female. These women are internationally recognised in their respective area of expertise. Such a network is unique, and it will send a powerful message about women working in the engineering sciences: it will provide positive role models for women; it will help to combat the phenomenon of “subconscious gender bias”; it will act as a magnet for women considering careers in science and engineering.

Outreach
The ESRs in POLKA have received specialist training in Outreach and Communication, and they will engage with the general public through dedicated science events and publications when the pandemic is over.

OVERALL OBJECTIVES

The ultimate goal of POLKA is to ease and accelerate the introduction of safe and reliable hydrogen combustion technology into the power generation, transport and manufacturing sectors. This will be done by generating new insight into the complexities of hydrogen combustion dynamics and by using this insight to develop technical solutions to the problems of thermoacoustic instabilities and flashback.

Research
POLKA has established a fertile research training network, where a cohort of 15 ESRs is performing numerical simulations, theoretical modelling and laboratory experiments in order to understand and mitigate instability problems and flashback in hydrogen combustion.

Training
POLKA is offering a unique and comprehensive training infrastructure, where education in fundamental science is supplemented by complementary skills training in entrepreneurship, outreach and gender issues. This training package is developing a new class of highly-skilled, well-rounded, creative and versatile young researchers with a broad base of technical expertise, who are able to think independently and stimulate innovation in Europe.

Gender-balance and inclusivity
POLKA has created an gender-balanced research environment, which is unique in the engineering sciences, and will attract more women into a scientific/technical career. It has also created a diverse and inclusive working atmosphere, which is an important source of innovation.
A significant amount of work has been performed in all five POLKA work packages:

WP1: Passive instability control

WP2: High-resolution/reduced-order simulations for hydrogen combustion dynamics

WP3: Analytical simulations of nonlinear interactions

WP4: Early detection of instabilities and flashback

WP5: Boiler design

The main results achieved so far are:

- The ability of micro-slit plates to absorb sound depends on their porosity and edge geometry.

- If the hydrogen percentage of a turbulent hydrogen-methane flame is increased, the flame consumption speed at first increases, reaches a maximum and then decreases.

- An efficient numerical code, based on a Green's function approach, has been developed and is giving first results for the amplitudes of thermoacoustic limit cycles in the presence of noise.

- An optical measurement of the temperature in a combustion chamber by a laser-controlled micro-bead has been performed successfully.

- A novel tube termination has been developed which promises to work well for the control of thermoacoustic instabilities.

- The NOx production of a boiler with a heat exchanger in the combustion chamber can be reduced by reducing its distance from the flame.
Economy
POLKA is en route to making scientific discoveries in thermoacoustics and aeroacoustics with technological applications. This will aid the design of gas turbines and domestic heating appliances with zero carbon footprint. Such technologies have an expanding market worldwide. There is a high demand in the renewable energy sector for employees with advanced technical skills and an innovation-oriented mind-set. POLKA is training young researchers to make them fit for such roles.

Environment and Society
POLKA is contributing to reducing the pollution caused by combustion, which is responsible for global warming. This has enormous and obvious benefits; in particular, it will advance the environmental and social well-being.
Logo representing improvements following research in the coupling of flames & sound waves
Early Stage Researcher Recruitment poster showing POLKA locations around Europe
Project members (virtually) attending the 1st Project Meeting in March 2020