Han Xu

• Ph.D
• Professor (Assistant) at Nanjing University of Science and Technology

Rotating detonation experiments were conducted using CH4/CO/H2 (methane/carbon monoxide/hydrogen) mixtures with varying CO contents, the modes of rotating detonation wave (RDW) propagation in the mixtures were analyzed, and the impact of CO content on the propagation characteristics of the RDW in the gas mixture was compared. Three propagation mode...

In a liquid kerosene rotating detonation engine (RDE), detonation waves often exhibit different propagation modes. The propagation characteristics with different modes are worthy of further study. To further investigate the propagation characteristics, a series of experiments was conducted, and the flow field characteristics under different modes w...

Hydrogen is a kind of promising alternative fuel applied in engines. However, the severe knock with a detonation onset is a huge obstacle for the application of hydrogen. Acoustically absorbing wall could suppress the detonation onset and thus it is found to be a new method to suppress the severe knock without the extra loss of hydrogen engine perf...

Our very recent work has experimentally demonstrated the successful operation of a liquid-kerosene-fueled ramjet/air-breathing rotating detonation engine with a cavity-based annular combustor. As a follow-up study, the present work aims to further reveal the effects of cavities on the initiation and propagation characteristics of detonation, and va...

Due to the inherent working mode of rotating detonation engine (RDE), the detonation flow field has the characteristics of pressure oscillation and axial kinetic energy loss, which makes it difficult to design nozzle and improve propulsion performance. Therefore, in order to improve the characteristics of detonation flow field, the three-dimensiona...

Detonation cycle realizes the high-efficiency utilization of the fuel. However, most of the fuel considered in the detonation engine is gaseous or liquid fuel, while seldom notice is focused on the solid fuel which is also a kind of important energy resource. In this research, experiments were conducted in a rotating detonation combustor, separatel...

Engine downsizing with a higher compression ratio and a higher boosting pressure improves the thermal efficiency of engines. However, with further downsizing of engines, knock intensity is aggravated until super knock occurs which is accompanied by a detonation wave that potentially can destroy engines rapidly. Therefore, it is essential to reveal...

The higher self-ignition temperature of hydrogen facilitates a higher compression ratio of H2ICEs (hydrogen internal combustion engines), which improves the thermal efficiency of engines. However, further increase of the compression ratio would unfortunately result in a super-knock, which would destroy engine parts severely. H2ICEs are vulnerable t...

The thermal ablation of the detonation tube is a key factor in pulse detonation engine (PDE) research. In this study, a symmetric two-phase detonation model and a cylinder heat conduction model are used for studying the features of transient heat transfer. The effects of the tube material and size on the heat transfer are analyzed using this model....

In this paper, the kerosene/air rotating detonation engines(RDE) are numerically investigated, and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation, instabilities, and propulsive performance. A hybrid MPI + OpenMP parallel computing model is applied and it...

With the demand of high efficiency, IC (internal combustion) engines have been pushed to their thermodynamic limits. As a result, severe knock occurs which would make a huge destruction to engine parts. Detonation is found to be the essence of such severe knock. In this research, a series of numerical simulations were conducted to prove that the de...

This work investigates numerically the effect of small obstacle induced perturbations on the re-initiation of a diffracted detonation wave and highlighted the importance of cellular instability. For successful re-initiation, sufficient cellular instabilities and triple points (either survived naturally or induced artificially) must be sustained to...

The advent of new drug therapies has resulted in a need for drug delivery that can deal with increased drug concentration and viscosities. Needle-free liquid jet injection has shown great potential as a platform for administering some of these revolutionary therapies. This investigation explores the detonative combustion phenomenon in gases as a si...

Shock wave formed in internal combustion engines under severe knock will reflect and converge in close space, causing severe damage to combustion chamber parts. However, the research on the failure of piston has not yet gone deeper. In order to reveal such a convergence mechanism and its destruction effects in cone-roof close space, a constant volu...

The transmission of detonation waves, propagating in a homogeneous, gaseous, reactive medium, from a tube into an unconfined space is well known to succeed or fail based on the tube diameter. Below a certain diameter, the detonation fails to transition into the unconfined space, while for a large enough geometry, the transition succeeds. This criti...

In this investigation, the diffraction and re-initiation process of unstable detonations propagating in a homogeneous, gaseous, reactive medium, from a tube into an unconfined space are analyzed. Results were obtained using simultaneous schlieren photography and soot foil records. The experimental investigation was carried out in an apparatus consi...

In internal combustion engines, severe knock is a destructive phenomenon that would converge the energy released by fuel burning to damage the piston so that the engine can't work anymore, which should be avoided. The destruction mechanism have been revealed in previous researches in which the focusing of shock waves is considered as a main reason...

Under severe knock of IC (internal combustion) engines, engine parts like pistons are vulnerable to be damaged rapidly, the mechanism of which remains unsolved. Especially how the chemical energy released from fuel burning is transformed into the force damaging the material of pistons is still unclear. In order to reveal the in-cylinder energy tran...

Excessive increase of methanol engines compression ratio will lead to severe knock，which will dam- age the piston． In order to reveal such a severe knock phenomenon，our research conducted several numerical simulations and then analyzed the chemical process of end gas，which revealed the mechanism that compression waves cause auto-ignition while auto...

Under severe knocks of internal combustion engines, parts like pistons and spark plugs are vulnerable to be damaged by energy convergence of shock waves. Furthermore, the damaged positions and failure modes have a significant regularity. In order to reveal the mechanism and avoid such damage, numerical simulations combined with detonation bomb expe...

In internal combustion engines, different combustion technologiescan result in different knocks, such as the conventional knock of gasoline engines, the super knock and the knock of HCCI engines. Though they are all caused by the auto-ignition of unburned mixture which leads to the oscillation burning, the rising rate and the oscillation amplitude...

For internal combustion engines, the knock of Homogeneous Charge Compression Ignition engines, the conventional knock of gasoline engines and the super knock are all caused by the auto-ignition of unburned mixture which leads to the oscillation burning, but their Maximal Pressure Oscillation Amplitude (MPOA) and Maximum Pressure Rising Rate (MPRR)...

A methanol mixture auto-ignition test is conducted on the first cylinder of a turbocharged intercooled diesel engine to analyze the pressure oscillation characteristics of methanol auto-ignition and study the forming law of destructive pressure wave in super knock. The results show that the probability of methanol auto-ignition tends to increase wi...

For the internal-combustion engine, super knock produced by new combustion system may cause detonation in combustion chamber, which may damage the piston. 2D numerical simulation which is conducted by Ansys Fluent is used to investigate the propagation and reflection of detonation wave produced in combustion chamber with cone type roof. The overpre...

2D numerical simulation which is conducted by Ansys Fluent is used to investigate into propagation and reflection of detonation wave produced in the ω combustion chamber. The overpressure distribution of top piston surface is found. Numerical simulation showed that the detonation wave could converge in special zone because of the shape of combustio...