High temperature effects in moving shock reflection with protruding Mach stem

The influence of high temperature effects on the protrusion of Mach stem in strong shock reflection over a wedge was numerically investigated. A two-dimensional inviscid solver applies finite volume method and unstructured quadrilateral grids were employed to simulate the flow. Theoretical analysis was also conducted to understand the phenomenon. Both numerical and theoretical results indicate a wall-jet penetrating forward is responsible for the occurrence of Mach stem protrusion. The protrusion degree seems to depend on the thermal energy buffer capacity of the testing gas. Approaches to increase the energy buffer capacity, such as vibrational relaxation, molecular dissociation, and increase of frozen heat caoacitv, all tend to escalate the orotrusion effect.

Physiological responses of people in working faces of deep underground mines

The research studied the influences of high temperature, high pressure, high humidity, noise and other harmful factors in mining conditions on the people health and safety, and investigated the impacts of confined environmental on human physiology factors, including temperature, humidity, noise, pressure,toxic and harmful gases in terms of environmental characteristics in underground mines and an artificial intelligence system for simulation of the environment in a confined space of deep mines. Our results show that the systolic pressure, diastolic pressure, mean pressure, heart rate, respiratory rate, typing test speed and memory level percentage are negatively correlated with temperature value, and positively correlated with humidity value; the human temperature and weight are positively correlated with temperature value, and negatively correlated with humidity value. This research lays the foundation for the study of interaction between the deep confined space environment and safety behavior.

Investigation on Combustion Characteristics and NO Formation of Methane with Swirling and Non-Swirling High Temperature Air

Combustion characteristics of methane jet flames in an industrial burner working in high temperature combustion regime were investigated experimentally and numerically to clarify the effects of swirling high temperature air on combustion.Speziale-Sarkar-Gatski(SSG) Reynolds stress model,Eddy-Dissipation Model(EDM),Discrete Ordinates Method(DTM) combined with Weighted-Sum-of-Grey Gases Model(WSGG) were employed for the numerical simulation.Both Thermal-NO and Prompt-NO mechanism were considered to evaluate the NO formation.Temperature distribution,NO emissions by experiment and computation in swirling and non-swirling patterns show combustion characteristics of methane jet flames are totally different.Non-swirling high temperature air made high NO formation while significant NO prohibition were achieved by swirling high temperature air.Furthermore,velocity fields,dimensionless major species mole fraction distributions and Thermal-NO molar reaction rate profiles by computation interpret an inner exhaust gas recirculation formed in the combustion zone in swirling case.

A novel phenomenological model using a sine function for finite-element simulation of large-strain hot deformation

In hot deformation, the flow stress curves of steels always present as two typical types: at relatively high temperature and low strain rate, the flow stress may first increase and then attain a steady value without reaching an obvious peak stress; in other situations, the flow stress decreases after reaching peak stress and then attains a steady value. A new phenomenological model,described by a sine-function equation, is proposed to define the relationship between flow stress and deformation parameters. A series of isothermal compressions for a carbon steel were carried out, as a case study, to obtain basic experimental data.Parameters of the new model were sequentially determined. The predicted results of the proposed model were compared with actual measured data. Good accuracy was found in the standard statistical parameters of correlation coefficient, root mean square error, and average absolute relative error with the values of 0.935, 7.137 MPa and 4.352%, respectively. Discussion of applications of different models in finite-element simulation demonstrated the benefit of the new model. When comparing the simulation results of three different deformation patterns with large strain, the new model showed 10%–20% lower predicted forming load than the original Arrhenius equation, and better applicability and reliability than modified Arrhenius equations.