Liquid atomization is a very complex issue, involving multiple length and time scales over several orders of magnitude. To better understand the atomization characteristics of the main injection in a lean premix prevaporize (LPP) combustor, a volume of fluid (VOF)–particle conversion algorithm Lagrangian particle tracking (LPT) coupled approach was proposed to simultaneously reproduce the primary and secondary breakup processes. A VOF model with an adaptive mesh refinement strategy was used to resolve the liquid disintegration on a large scale. The small liquid structures qualified as droplets were transformed into discrete particles based on particle conversion criteria. Next, these particles were tracked using the LPT method to simulate the secondary breakup process. The proposed coupled method used in the Eulerian/Lagrangian framework was validated against liquid jet in crossflow experimental data. The numerical results achieved good agreement with the experimental data. Finally, the proposed method was used to predict the atomization characteristics of the main injection in an LPP combustor under various aerodynamic conditions. Qualitative and quantitative information about liquid deformation and spray characteristics were obtained, which varied depending on the aerodynamic parameters.

Combined-cycle pulse detonation engines are promising contenders for hypersonic propulsion systems. In the present study, design and propulsive performance analysis of combined-cycle pulse detonation turbofan engines (PDTEs) is presented. Analysis is done with respect to Mach number at two consecutive modes of operation: (1) Combined-cycle PDTE using a pulse detonation afterburner mode (PDA-mode) and (2) combined-cycle PDTE in pulse detonation ramjet engine mode (PDRE-mode). The performance of combined-cycle PDTEs is compared with baseline afterburning turbofan and ramjet engines. The comparison of afterburning modes is done for Mach numbers from 0 to 3 at 15.24<!-- --> <!-- -->km altitude conditions, while that of pulse detonation ramjet engine (PDRE) is done for Mach 1.5 to Mach 6 at 18.3<!-- --> <!-- -->km altitude conditions. The analysis shows that the propulsive performance of a turbine engine can be greatly improved by replacing the conventional afterburner with a pulse detonation afterburner (PDA). The PDRE also outperforms its ramjet counterpart at all flight conditions considered herein. The gains obtained are outstanding for both the combined-cycle PDTE modes compared to baseline turbofan and ramjet engines.

This paper presents a hydrodynamic analysis of binary immiscible metallurgical flow by a numerical simulation of the rheomixing process. The concept of multi-control is proposed for classifying complex processes and identifying individual processes in an immiscible alloy system in order to perform simulations. A brief review of fabrication methods for immiscible alloys is given, and fluid-flow aspects of a novel fabrication method: rheomixing by a twin-screw extruder (TSE), are analysed. Fundamental hydrodynamic micromechanisms in a TSE are simulated by a piecewise-linear volume-of-fluid (VOF) method coupled with the continuum surface force algorithm. This revealed that continuous reorientation in the TSE process could produce fine droplets and the best mixing efficiency. It is verified that a TSE is a better mixing device than a single-screw extruder and can achieve finer droplets. Numerical results show good qualitative agreement with experimental results. It is concluded that rheomixing by a TSE can be successfully employed for casting immiscible engineering alloys due to its unique characteristics of reorientation and surface renewal.

To guide ultra-compact combustor (UCC) engineering, simulations were conducted about turbulent premixed combustion in a high acceleration field which is called high-g combustion, along with a detailed investigation on the evolution of turbulent premixed flame in a rotating tube of stoichiometric propane-air. The rotation of the tube was mimicked by modified momentum source term in the unsteady 2D simulations to decouple the centrifugal force and the Coriolis force, the latter of which was usually neglected in previous reports. A good agreement was found between the simulation result and experimental data, along with a discovery of the phenomenon that flame speed was accelerated by the imposed acceleration field. Further study indicated that the flame acceleration phenomenon can be attributed to the flame corrugation induced by the Rayleigh–Taylor instability (RTI). The Coriolis force was found to be non-negligible in high-g combustion since the Coriolis acceleration could be at the same magnitude as the centrifugal acceleration, and the observed flame speed was nearly 20% lower without the Coriolis force. The current study revealed that the high-g combustion in an open chamber due to the absence of pressure wave/flame front interaction could not be fully compatible with predictions derived from closed chamber experiments and that the Coriolis force could not be ignored in the high-g combustion process.

Li-ion batteries are widely used in electric vehicles for their superior performance. To investigate a simple and efficient method for the Li-ion power batteries, the cold plate with four types of structures A, B, C, and D were established, respectively. Subsequently, the effects of micro-channel thickness and width on the cooling performance of battery thermal management systems were analyzed by using a numerical simulation method. The results show that with the increases of the micro-channel thickness, the maximum temperature (Tmax) of the cold plate is gradually increased under structures A, B, and C, while it is gradually decreased under structure D. The standard deviation of temperature (T?) of the cold plate of structure A was less affected by the change of the micro-channel thickness. Under structures B, C, and D, the temperature uniformity of the cold plate can be well maintained when the micro-channel thickness was 1.0 [mm]. With the increase of the micro-channel width, the Tmax and T? of the cold plate are gradually increased in all cases, while the ?P from the inlet to outlet is gradually decreased. The temperature uniformity of the cold plate is well maintained by structure C. The decreasing amount and changing range of ?P caused by the change of micro-channel width is smaller than caused by the change of the thickness.