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High-speed flows over a 34° compression corner subjected to several types of applied electromagnetic fields are numerically investigated. A coupled model for the turbulent flow field and the externally applied electromagnetic field is established based on the low magnetic Reynolds number assumption. The advection upstream splitting method with pressure-based weight function (AUSMPW) scheme and the lower upper symmetric Gauss Seidel (LUSGS) method are implemented to solve turbulent magnetohydrodynamic (MHD) flow equations. Numerical results demonstrate that the performance of MHD separation flow control is determined mainly by the Lorentz force in the turbulent boundary layer. For the counter-flow Lorentz force, the velocity fluid in the boundary layer can be retarded, and a significant temperature increase was observed. The decelerating Lorentz force significantly brings negative effects on the turbulent skin friction coefficients and increases the static pressure locally. Furthermore, the position of the MHD zone has a significant impact on the control efficiency of the ramp-induced separation. With an external electric and magnetic field applied, the low-velocity fluid in the boundary layer can be accelerated, and the Lorentz force directed along the stream can reduce the size of the separation bubble. [ABSTRACT FROM AUTHOR]

This study investigates the mixing processes of liquid jets in supersonic crossflows at a Mach number of 2.1 by using numerical simulations that employ the Coupled Level-Set/Volume-of-Fluid (CLSVOF) method, which is based on the Delayed Detached Eddy Simulation (DDES). The instantaneous spray morphology from the simulations agreed well with the experimental data. The spray presents the 'Ω' shape when viewed from the front, and the maximum error in the penetration depth was 15% from a side perspective. The direction of the air movement determined the shape of the liquid column shearing and breaking. In turn, the breaking process of the liquid jet significantly affects the structure of the air flow. Three-dimensional flow around the liquid column occurred when the supersonic incoming flow impinged on the liquid column, ultimately forming counter-rotating vortex pairs (CVP) in the inner region of the spray. Evolution of the reverse vortex pair accelerated the mixing process of the spray. Single liquid jet was used as a basis to further study double jets in Mach 2.1 airflow. The results show that the breaking length and penetration depth of the downstream jet are significantly improved. [ABSTRACT FROM AUTHOR]

The mixing process of a liquid jet in supersonic crossflow with a Mach number of 2.1 was investigated numerically using large eddy simulation (LES) based on the Eulerian-Lagrangian method. The gas phase was described using the Navier-Stokes equations and the liquid phase was represented using discrete droplets, which were injected and tracked in the computational domain individually according to Newton's second law of motion. The KH (Kelvin-Helmholtz) breakup model was used to calculate the droplet stripping process, and the secondary breakup process was simulated by coupling the RT (Rayleigh-Taylor) breakup model and the TAB (Taylor Analogy Breakup) model. Two-way coupling was enforced to consider the momentum and energy exchange between the gas and the droplets. It was found that the LES predicted spray characteristics, including spray penetration and cross-sectional distribution, agree reasonably well with the experiment. The major gas flow structures such as the bow shock, the large-scale vortices, and the recirculation zones were replicated successfully in the simulations. It was found that the gas flow structures have a significant effect on the mixing process of the droplets. The simulation results revealed that two sets of counter-rotating vortex pair (CVP) exist in the gas-liquid mixing region. Under the influence of CVP, part droplets were transported to the near wall region and subsequently to both sides of the core spray region. The formation mechanism of the CVP was analyzed by comparing the pressure gradient and the source term of droplets in the Navier-Stokes equations. Differences of the mixing process of liquid jet in supersonic crossflow, gas jet in supersonic crossflow and liquid jet in incompressible crossflow were identified. [ABSTRACT FROM AUTHOR]

• A reliability evaluation method of software in NPP DCS is proposed. • TheSRGM and software failures detected in V&V are combined to assess reliability. • The BBNs method is investigated and compared with the NHPP model. • The challenges for NHPP are summarized. With the application of digital technology, the software used in various systems has become increasingly important, as well as complex. This increase in complexity and scale has led to an increase in the probability of software failure. Quantitative reliability evaluation of the digital instrumentation and control system software used in nuclear power plants represent a significant challenge. This study uses a non-homogeneous Poisson process model for quantitative evaluation of the software reliability of a nuclear power plant safety digital control system (DCS), which is the research object. To analyse the research object, a software test environment is established, and the research object is tested to obtain the software failure data. The software reliability growth model, which is widely used in other industries, is combined with data on nuclear power plant DCS software defects that obey a non-homogeneous Poisson process, to construct a non-homogeneous Poisson process model. The formulas for software reliability indicators such as total failures, remaining failures, failure rate (failures per week), reliability, and time to next failure(s) are derived. The software failure data obtained from the test are used to determine the variables of the model based on maximum likelihood estimation; the estimates are then used to quantitatively evaluate software reliability-related indicators. Finally, the minimum correlation error method is used to analyse the error by comparing the actual and model prediction results. The model can evaluate the current reliability level of software and predict the impact of subsequent reliability test results. The findings from this study can provide data support for evaluating the reliability of nuclear power plant DCS software. Therefore, this study can be significant for further research on the reliability of nuclear power plant DCS software. [ABSTRACT FROM AUTHOR]