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Knock prevention and increase of reliability and efficiency of high power gaseous internal combustion engines

Periodic Reporting for period 2 - Knocky (Knock prevention and increase of reliability and efficiency of high power gaseous internal combustion engines)

Reporting period: 2017-12-01 to 2019-11-30

Main research targets of the project are as follows: to work out knock model for its prediction and to work out effective methods for knock reduction in high power output gas fuelled stationary engines for heat and power generation. Academic and commercial R&D centres herein undertake the investigation of the reduction of the abnormal combustion phenomena of knock in internal combustion engines. Combustion knock limits the efficiency of the engine and deteriorates engine performance while simultaneously contributing to engine destruction, thus it crucially reduces engine reliability. Reducing or eliminating combustion knock increases durability and also engine efficiency, hence reducing CO2 emissions.
The inter-sectoral research encompassed in this proposal concerns high-power stationary engines fuelled with gaseous fuels (biogas, natural gas, coke gas) working in combined heat and power (CHP) systems.
As result of the synergies and breadth of expertise, a resultant acceleration in research finding is expected with complementary investigation conducted within both the companies (Wartsila, AVL, Motortech) and universities involved that finally should result in successfully solving the related challenges.

Importance to society
Creation amongst the project participants of a strong science-engineering group is planned. It will initiate academic-industry based cluster with the aim to extend collaboration in the field of power and combustion engines.
Hence, both local and global societies should benefit from access to knowledge that leads to well-educated people. Participation in Researcher's Nights is one of the measures taken in this case.
By solving scientific and technoological problems dealing with the combustion knock, the engine will work more efficiently and more reliably.
Hence, the engine consumes less fuel, what implies to the following:
- it generates more power, hence reduces risk of energy defficiency
- and emits less toxic pollutants as well as CO2,
Therefore, it contributes to reduce impact of power generation by gas fueled engines on natural environment, so increases comfort of living for people.

The overall Objectives
The main project objectives are as follows:
1) to obtain a synergy and extended interaction by joining several scientific and engineering disciplines to investigate the attributes and causality associated with abnormal combustion in the internal combustion piston engine.
2) Specific technological objectives of the project are:
to recognize details associated with combustion knock,
to determine methods for knock prediction and reduction,
3) to stimulate collaboration between industry and academic entities.
"The following key-leading research works were realized:
- tests on combustion of various fuels in the SI engine at various working conditions
- chemical analysis of fuels applied to IC engines,
- 3D CFD AVL FIRE modeling – spark discharge and ignition phase
- 3D CFD FOAM modeling air-gas mixture preparation
- Thermo-chemical and thermodynamic analysis of knock occurrence in the SI engine - 0D modeling
- Digital signal processing (DSP) and analysis of combustion pressure plots
- Statistical analysis of engine combustion events.

Main Results
WP 1
3D-CFD simulation of flame propagation and end-gas pre-reactions was done.
On knock onset detection from a model data was collected. Computational model was created.
RANS and LES modelling approaches and validation of simulation results are completed.
Knocking combustion of gaseous fuels in RCM was measured and modelled.
The developed ignition model validation was done.
All the tasks were completed. Esential content of research works conducted at those tasks was to collect data for the following:
Methane number prediction,
Combustion modelling,
Knock intensity modelling,
Flash boiling modelling,
Spark ignition modelling.

WP 2
Engine indicating – in-cylinder pressure data acquisition was completed. Results from engine indicating were used to build a data base, which is required for knock model calibration.
Updating the Single Cylinder BOOST Model, Measurement Matrix Status, Measurement Matrix Update, Creation & Parametrization of the 4-Cylinder Engine Model.
Exhaust toxic emissions and PM measurements from the engine working at various loads and combustion related parameters were recorded and analyzed.
Combustion tests were extended with additional parameters: variable valve timing and overexpanded cycle as well as additional tests on potential anti-knock additives to fuels (glycerol, water, aromatic hydrocarbons etc.) were also conducted.

WP 3
Development of a model of large 4-stroke engines: calibration of large system model.
All these tasks below were completed.
Data processing was focused on the following: in-cylinder combustion pressure data collection, pressure rectification, conversion and filtering – methods and codes, temperature calculation.
Test works included as follows: data mining and processing, data accomplishments, data processing for knock evaluation and its correlations with engine parameters.

WP4 Flame visualization.
Several images of flame development were taken as training works with optical systems.
The research works contained injection, spraying, ignition and flame kernel development.
Digital image processing. Tests on spraying at various injection pressures.

WP5 Knock reduction measures.
Several correlations between knock and engine parameters were worked out. Conclusions were drawn.

WP6 Dissemination.
The web page was built.

The seminar #1 was organized as the main part of the 44th International Scientific Congress on Powertrain and Transport Means – KONES 2018.
Seminar #2 was organized at MTU, USA.
2 Workshops, conference and symposium were organized.
This task is continued over the project realization. 25 papers were published as showed further. All papers are published with the open access option.

In the WP7 Management. The kick-off meeting, 4 mid-term meetings and 4 meetings trough webinars were done."
Progress beyond state-of-the-art is in the following fields:
- characterization of knock onset in the gas fueled spark ignited engine,
- working out knock prediction and reduction methods.
By now, a new model for knock occurrence has been worked out. It is implemented in the commercial AVL FIRE software for modelling engine combustion phenomenon and work cycles.
Expected results:
- in AVL - development in the electrical discharge model and the ignition model, development of computer codes for ignition modeling and flame propagation,
- in Wartsila – implementing Combustion Research Unit (CRU) and Rapid Compression Machine (RCM) to work on various fuels, working out and implementing computer codes into CRU and RCM to control combustion process, The RCM experimental work and AVL Boost model are now being implemented,
- in MOTORTECH – working on air-gas premixing problems in gas mixing units.
- in MTU - visualisation of injection, ignition and flame kernel development.