Session: 04-18: Pressure Gain Combustion I

Paper Number: 82393

82393 - Experimental Investigations of Hydrogen Fuelled Pulsed Detonation Combustor 

The greenhouse gas emissions represent a clear concern, forcing worldwide nations to adopt drastic regulations to decrease pollution. According to the Green Deal released by the EU Commission, Europe is to reduce by 55% the net greenhouse gas emissions by 2030, while by 2050, Europe is expected to become the world's first climate-neutral continent (Antarctica aside). A major contributor to Carbon emissions is the power generation industry, which accounts for about 72% of the global manmade CO₂ emissions, with generation of electricity and heat as the prime contributor (31%). Consequent political decisions directly target power generation systems, which are one source of greenhouse gas emissions. Such systems include both land, marine, or aerial propulsion systems, and electrical power generation systems than use engines to convert the chemical energy stored in the fuel to work, and then to electricity.

The modern industry is in continuous development on all branches, to discover new ways of reducing emissions and contamination and, although great efforts are made to control these issues, it is said that classic deflagration propulsion systems and applications are coming closer and closer to a stagnation ceiling, where only small improvements can be achieved. Judging its enormous potential in both industrial and mobility decarbonization, Hydrogen, has become an important hope in the future energy mix. To achieve a safe and reliable energy conversion, Hydrogen combustion must be thoroughly investigated, as Hydrogen is known to be a highly flammable and volatile substance and presents storage complications, due to its low density. An elective combustion approach, based on Hydrogen detonation combustion has received special attention in recent studies, due to its potential to overcome the efficiency of deflagration combustion. The advantage of this system is the pressure gain heat addition, which enables higher cycle efficiencies and faster energy release rate.

This paper addresses the above mentioned issues, through in-depth analysis of a Hydrogen fuelled pulsed detonation combustor, to contribute to the understanding of the high-speed mixing performance and to improve the specific know-how regarding the detonation combustors. The experimental facility consists of a test rig that incorporates the pulsed detonation combustor, connected to both hydrogen and compressed air supply lines. The mixing capabilities of the two gases is promoted through crossflow jet, since H₂ is injected axially by means of an injection plate, while the oxidizer inlet is normal to the combustor longitudinal axis. The ignition is triggered by a spark plug placed downstream the mixing chamber. Both supply lines are instrumented with manometers, thermocouples and flow meters.

By means of Z-type Schlieren visualization technique, the structure of the combustor exhaust plume is determined to capture the intrinsic unsteady phenomena of the ignition. Not only qualitative results are presented, such as shock waves, under expanded jet configuration and deflagration-to-detonation properties, but also quantitative results in terms of velocity. To further evaluate the detonation phenomena, the pulsed detonation combustor benefits from high-speed pressure probes, placed both in the mixing chamber, as well as the exhaust pipe.

The objectives of the extensive experimental campaign are twofold. As both fuel and air injection in the pulsed detonation chamber under study is controlled by aerodynamic valves created by shock wave systems generated and amplified by Hartmann resonators, the experimental study helps to gain insight into the aerodynamics of this process and its fundamental operating frequency. In addition, the ignition is investigated for different equivalence ratios. Very high equivalence ratios lead to incipient detonation regimes, while for very low ones, no ignition occurs. The ignition regimes are thoroughly assessed by means of Schlieren visualization and pressure signals thus providing results in terms of cycle operating frequency, shock system structure and pressure.

Presenting Author: Andrei Vlad Cojocea Romanian Research & Development Institute for Gas Turbines - COMOTI

Presenting Author Biography: Ing. Andrei Vlad Cojocea was born in 1995 in Bucharest, Romania and is a Scientific Researcher at the National Research and Development Institute for Gas Turbines COMOTI, in Bucharest, Romania. He is an assistant professor and a PhD candidate within the Aerospace Doctoral School, at Polytehnic University of Bucharest. He has strong education background in the aerospace field, gained during his postgraduate studies: MSc at Imperial College London department of Aeronautics and MRes at Von Karman Institute for Fluid Dynamics, in the Turbomachinery department. He has advanced knowledge of the complex processes includes topics such as fluid dynamics, H2 combustion, detonation engines, high-pressure turbines, supersonic flows and turbulence modelling. He is author of several scientific papers and is involved in two international research projects in ESA and H2020 programs and in one national research project. In addition, he also contributed to the construction and development of TESS detonation test rig of COMOTI and is part of the implementation team for its expansion. His current research interests are related to detonation combustion and carbon free fuels (including Hydrogen) for gas turbines.

Authors:

Andrei Vlad Cojocea Romanian Research & Development Institute for Gas Turbines - COMOTI
Ionut Porumbel Romanian Research & Development Institute for Gas Turbines - COMOTI
Tudor Cuciuc Romanian Research & Development Institute for Gas Turbines - COMOTI
Bogdan Gherman Romanian Research & Development Institute for Gas Turbines - COMOTI
Mihnea Gall Romanian Research & Development Institute for Gas Turbines - COMOTI
Daniel Eugeniu Crunteanu Polytehnic University of Bucharest