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.

Analysis of thermal-mechanical coupled characteristics of vehicle twin-tube shock absorber

A comprehensive model that included mechanical dynamics of the shock absorber coupled with its thermal properties was proposed innovatively.Moreover a thermal-mechanical coupled model which reflected the closed-loop positive feedback system was established by using MATLAB/SIMULINK,and some curves of shock absorber temperature rising characteristic were obtained by simulation ＆computation under several operating modes and different parameters conditions.Research results show that：shock absorber design parameters,external excitations,and thermo-physical properties parameter,such as oil density have effect on the shock absorber temperature rising characteristic.However other thermo-physical properties parameters,such as oil specific heat,cylinder density,cylinder specific heat,and cylinder thermal conductivity,have no effect on it.The results may be used for studying reliability design of the shock absorber.

Role of temperature fluctuations and shocks during refrigeration on pork and salmon quality

Refrigeration is considered a prime technology for preserving meat products.Temperature alterations are commonly ignored by industry during refrigeration,which have impacts on product quality.Thus,we conducted research on pork loin and salmon fllets that were preserved for o,5,9,12,and 15 d,where different temperature fluctuations and shocks were established on 4℃.Data revealed that several meat parameters such as total volatile basic nitrogen,total viable count,and lipid oxidation were significantly changed in the±2 C fluctuations group compared with the constant temperature group.Additionally,both the temperature fluctuations and shocks groups had accelerated myofibril protein degrad-ation,while desmin expression and species richness/diversity of bacteria were significantly reduced in the±2℃fluctuations group compared with the constant temperature group.Briefly,temperature fluctuations and shocks accelerated the destruction of muscle structural integrity.Furthermore,both conditions accelerated meat spoilage by progressively expanding the water-loss channels,which can reduce meat edibility.This study provides a new theoretical basis for the proper use of refrigerated temperatures for storing meat products.

Modeling the temperature shock of elastic elements using a one-dimensional model of thermal conductivity

This paper considers the task of evaluating micro-accelerations arising due to the temperature shock of large elastic elements when a small spacecraft leaves the Earth’s shadow.In this case, a one-dimensional model of thermal conductivity is used. Its solution wasobtained by the method of direct approximation with the construction of differenceschemes. It is shown that the accuracy of estimating micro-accelerations is commensurate with the accuracy of solving by a three-dimensional model of thermal conductivity.The proposed model allows reducing the time to obtain estimates and significantly simplifies the task at hand. The results of the work can be used in the formation of thedynamic characteristics of a small spacecraft for technological purposes.