Numerical analysis of thermal radiation of spacecraft on orbit based on SINDA/FLUINT

Thermal stability is an important indicator to measure the reliability of aerospace equipment, and the space thermal environment is complex, and the commonly used thermal analysis software for ground equipment can no longer meet the needs. For this reason, based on the thermal design analysis software SINDA/FLUINT, taking a spacecraft as the research object, the thermal balance equation is first established. Then, use the thermal desktop software to establish a numerical model, and use the SINDA/FLUINT software to solve the heat transfer process. Finally, the thermal desktop is used to post-process the calculation results and analyse the thermal radiation of the spacecraft.

On air “sensed temperature” in Russia’s northern regions and its significance for geological prospecting

Research aim is digital estimation of air “sensed temperature” for Arctic and other cold areas of Russia. Relevance of the work is determined by Arctic geological survey for oil and gas prospecting. Research methodology includes the generalization of the results of previous studies and the application of some new ideas. Results. All measures of temperature senses can be divided into two classes: those based on the thermal balance equation and empirical ones. Without exception, no “effective” temperatures have a universal character and their use is good only for those regions for which they were developed. For Siberia and Russian Arctic segment, it is possible to apply “reduced temperature” by Adamenko-Khairullin based on information on wind speed, air temperature and radiation balance. The latter can be measured with actinometers or estimated from publications. Sphere thermometer readings give directly sensed temperature provided that the sphere has a proper diameter. Nevertheless there is not onevalued universal methodology to calculate air “sensed temperature” mentioned in weather forecast. The authors simplified “sensed temperature” calculations as much as possible. Field of implementation. Digital estimation of air “sensed temperature” is essential for geological prospecting in the northern territories of Russia. Conclusion. There is an objective need in “sensed temperature” calculations including operational decisions in industries working in Arctic conditions. Three simple but effective formulas for “sensed temperature” of air were supposed for the biggest part of Russia’s northern territories.

Non-contact Dynamic Capacity-Increasing of Overhead Conductor Based on Cooling Tester (CT)

The traditional dynamic capacity-increasing technology of overhead conductors needs to monitor the operation state of conductors (temperature, sag, etc.), and the relevant sensors are usually installed directly on the surface of conductors. The installation cost is high, and the operating maintenance is complicated. In this paper, a non-contact dynamic capacity-increasing method for overhead conductors based on CT is proposed. Firstly, the theory of the non-contact dynamic capacity-increasing method for conductors is introduced, and a cooling testing device is designed according to the theory. Then, the cooling index is defined to represent the cooling capacity of the object, and the corresponding cooling indexes for the conductors and the CT are calculated based on the steady-state thermal balance equation. By establishing a cooling correlation model for the conductors and the CT, the calculation for the dynamic ampacity of the conductors can be obtained. Finally, the cooling conditions of cooling testing device at different ambient temperatures and wind speeds are calculated through the finite element simulation method. Combined with the dynamic capacityincreasing method proposed in this paper, the corresponding ampacity value are obtained, and the effect of capacity increase is analyzed. The results show that the non-contact dynamic capacity-increasing method based on the CT has obvious effect in capacity-increasing compared with the static ampacity.

The Micromorphic Approach to Generalized Heat Equations

In this paper, the micromorphic approach, previously developed in the mechanical context is applied to heat transfer and shown to deliver new generalized heat equations as well as the nonlocal effects. The latter are compared to existing formulations: the classical Fourier heat conduction, the hyperbolic type with relaxation time, the gradient of temperature or entropy theories, the double temperature model, the micro-temperature model or micro-entropy models. A new pair of thermodynamically-consistent micromorphic heat equations are derived from appropriate Helmholtz-free energy potentials depending on an additional micromorphic temperature and its first gradient. The additional micromorphic temperature associated with the classical local temperature is introduced as an independent degree of freedom, based on the generalized principle of virtual power. This leads to a new thermal balance equation taking into account the nonlocal thermal effects and involving an internal length scale which represents the characteristic size of the system. Several existing extended generalized heat equations could be retrieved from constrained micromorphic heat equations with suitable selections of the Helmholtz-free energy and heat flux expressions. As an example the propagation of plane thermal waves is investigated according to the various generalized heat equations. Possible applications to fast surface processes, nanostructured media and nanosystems are also discussed.

A Method to Estimate the Error of Adiabatic Temperature Rise Testing Device

The surface temperature of a testing sample should be immediately adjusted to equal to the central point when testing adiabatic temperature rise of concrete. However, due to the insufficient tracking accuracy, there are temperature differences between the environment and the central point temperature. In this paper, the heat loss of the sample is deduced based on thermal balance equation and an assumption that the heat passing through cylindrical surface temperature and through the two ends of the sample do not affect each other, and the total heat losses of the sample can be calculated by adding the heat passing through cylindrical surface and the heat passing through two ends. Then, according to the relationship between heat and temperature, the maximum error caused by the adiabatic temperature rise testing device was deduced, and the proposed measurement accuracy of the adiabatic temperature rise testing device was presented. According to the results of the verification case, a corrective constant should be used to modify the deduction.

Calculation Method of Justification of Technical Actions for Prevention of Ice Dams Formation on Buildings with a Pitched Roof

The article presents the methodology of thermal balance equation generation for cold attics. This methodology is aimed to provide the scientific basis for engineer activities to prevent the ice hillock building-up on roofs during the periods of the lowest temperature of outside air. The complex of actions that leads to reduction of damages from buildings of thermal energy is listed, heating up to improvement of parameters of a microclimate in the operated rooms of the top floors of buildings. For realization of these actions any materials and technologies providing the necessary level of thermal isolation for the concrete building and satisfying to the fire-prevention and sanitary and hygienic requirements existing in the territory of the Russian Federation are used

Heat Balance of Extinguishing Process of Flammable Liquid by Sprayed Water

This article considers two alternate solutions of a thermal balance equation. The first solution allows us to trace the decrease of a flammable liquid surface temperature to a temperature lower than fuel flash point at which combustion is stopped. And the second solution allows us to analyze the decrease of burnout rate to a negligible value at which steam-air mixture becomes nonflammable.

Analysis of Monolithic Algorithmic Schemes for an Energy-Consistent Variational Formulation of a Coupled Thermo-Visco-Elastic Problem

A new variational formulation of coupled thermo-mechanical boundary-value problems has been recently proposed [1, 2], allowing to write mechanical and thermal balance equation under the form of an optimisation problem of a scalar energy-like functional. This functional is analysed in the framework of a thermo-visco-elastic problem, considering a strong coupling by taking into account the temperature dependency of mechanical properties. Different algorithmic schemes were tested, aiming to find the one that exhibits best computational performance. A simplified case shows that the optimum of the scalar energy-like functional is a saddle point.

Convective Heat Transfer in a Rotor Stator System Air Gap With Multiple Suctions of Fluid Through the Stator

The experimental work presented in this paper relates to the local convective heat transfer on the rotor surface in the airgap of a discoidal rotor stator system. The stator used in these experiments is a multiperforated disk in which an air suction due to the rotation of the rotor comes through and enters the airgap. A thermal balance equation was used to identify the local convective heat transfer coefficient, with temperatures as boundary conditions, which have been measured by infrared thermography. The influence of the suctions is discussed for an interdisk dimensionless spacing interval G ranging from 0.01 to 0.16 and for Re between 129,000 and 516,000. Results are compared with precedent studies in which we obtained Nusselt numbers with a closed rotor stator system in which stator is a full disk and a rotor stator system with one hole at the stator center. It is shown that multiperforated stator can or cannot improve the rotor cooling, depending on G and Re.

Visual Computation of Thermohydrodynamic Lubrication of Dynamically Loaded Journal Bearings

The Reynolds equation and energy equation with the thermal balance equation in combination were applied to build the thermohydrodynamic (THD) computational model of the dynamically loaded journal bearings. The most popular development platform——Visual C ++ in the field of computer science and the drawing platform of AutoCAD were combined with the medium of ObjectARX and the object oriented programming technology was used, on the basis of which, the visual computational software of the THD lubrication of the dynamically loaded journal bearings for main shaft and connecting rod bearings of automobile engines was developed. The analysis results of an example indicate that the bearing behaviors are closely tied to the radial clearances and inlet lubricant temperature of the bearing.