In the process of outdoor temperature change, it is beneficial to improve the comfort of thermal users to formulate adjustment and control strategies according to the actual needs of each user. In this paper, differen...
In the process of outdoor temperature change, it is beneficial to improve the comfort of thermal users to formulate adjustment and control strategies according to the actual needs of each user. In this paper, different adjustment modes are established according to the thermal comfort of users, and the control strategies of rising and cooling within 0, 30 and 60 minutes are proposed, and the indoor temperature control effect and heating energy consumption of each adjustment mode under different control strategies are analyzed. The results show that: in different modes, when the rise and cooling time increase, compared with the design room temperature, the indoor temperature difference under the control mode is smaller, but the time needed to reach stability is longer. At the same time, the total heat load is unchanged, but the total pump work decreases.
The design of specific airfoil for wind turbine is a crucial factor in the research of wind turbine performance and stability. Based on bionic methods and numerical optimization methods, a brand new airfoil design met...
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The design of specific airfoil for wind turbine is a crucial factor in the research of wind turbine performance and stability. Based on bionic methods and numerical optimization methods, a brand new airfoil design method is proposed without relying on any traditional airfoil and airfoil design experience. This study proposes a re-evolution method (numerical optimization methods) suitable for designing bionic airfoils based on the previously proposed bionic airfoil (Dol-Rot24°), which was inspired by the Dall's Porpoise. According to this method, a new airfoil is successful designed that gives consideration to both aerodynamic performance and roughness sensitivity. The research content mainly focuses on two aspects: new airfoil design and the new airfoil performance verification. In terms of the new airfoil design, a surrogate model based on radial basic function (RBF) is established for predicting aerodynamic performance and roughness sensitivity of airfoils. This surrogate model can significantly reduce the cost of bionic airfoil optimization calculations, and control the time of 8000 optimization iterations within 1 minute. Based on the actual engineering environment of a horizontal axis wind turbine, the multi-island genetic algorithm is used to adjust the profile of the Dol-Rot 24° airfoil. The optimized airfoil is named Dol-Rot 24° opt. In the performance verification of the Dol Rot 24° opt airfoil, it is found that compared with the Dol Rot 24° airfoil, the lift coefficient of the Dol Rot 24° opt airfoil is increased by 171.06%, and the lift-to-drag ratio is increased by 52.41% at most. Moreover, the roughness sensitivity of the Dol-Rot 24° opt airfoil is also the best among the three airfoils (S809, Dol-Rot 24°, Dol-Rot 24° opt). By modeling the three airfoils according to the NREL Phase VI wind turbine blade parameters and conducting numerical simulations, it is found that the newly optimized wind turbine blades exhibit greatly improved energy efficiency. Th
T-junction is an essential component in piping system of various thermal systems. When hot and cold fluid mixing in the T-junction, several compound mechanisms (like turbulent mixing, turbulent penetration, fluid stra...
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ISBN:
(数字)9798350350326
ISBN:
(纸本)9798350350333
T-junction is an essential component in piping system of various thermal systems. When hot and cold fluid mixing in the T-junction, several compound mechanisms (like turbulent mixing, turbulent penetration, fluid stratification) make the mixing characteristics more complex. To clearly reveal such mixing mechanism with non-isothermal fluids, an experimental study was conducted with Ultrasound Doppler Velocimetry (UDV) and fast-response thermocouples bundle. The results show that the local velocity uncertainty of the UDV is within 10%, the uncertainty of the thermocouple bundle is 0.5°C, and the response time is 66.7 ms. After verification, the mixing characteristics between the main and branch pipe under different momentum ratios and temperature differences were discussed. It is shown that as the momentum ratio decreases, the location of the most intense radial temperature fluctuations and velocity fluctuations shifts towards the lower wall. At the same time, the peak flow rate in the cross-section increases by 35.7% and the main branch fluid mixing is more homogeneous. As the temperature difference increases, the thermal stratification is more pronounced and the velocity fluctuation peak moves towards the upper wall of the pipe.
Based on the Integrated Severe Accident Analysis (ISAA) code, this paper studies the influence of thermo-physical properties of Accident Tolerant Fuel (ATF) materials on the plant responses to severe accidents. By sel...
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The meshless Lagrangian method (particle method) demonstrates significant advantages in simulating multiphaseflows with highly dynamic phase interfaces and has been widely applied in research areas such as ocean engi...
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The primitive pseudopotential-based scheme (PP scheme), the modified pseudopotential-based scheme (MP scheme) and the improved virtual-density scheme (IVD scheme) are the three most widely used contact angle schemes t...
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The primitive pseudopotential-based scheme (PP scheme), the modified pseudopotential-based scheme (MP scheme) and the improved virtual-density scheme (IVD scheme) are the three most widely used contact angle schemes to simulate wall wetting characteristics in the pseudopotential lattice Boltzmann (LB) model under isothermal conditions. In this paper, these three widely used contact angle schemes are applied to simulate the problem of sessile droplet evaporation on a heated substrate, which is a non-isothermal phase-change process where temperature varies spatially and temporally. It is found that (i) using the PP scheme (primitive pseudopotential-based scheme) and the MP scheme (modified pseudopotential-based scheme) may lead to algorithmic instability problems in certain ranges of contact angles, deformation of droplet interface shape or Marangoni vortices shape, generation of unphysical vortices near the heated substrate, or result in erroneous temperature distributions near droplet triple-phase line. (ii) The IVD scheme (improved virtual-density scheme) has better algorithmic stability than the PP scheme and MP scheme (primitive pseudopotential-based scheme and the modified pseudopotential-based scheme), where the droplet interface shape and Marangoni vortices shape are correct, the unphysical vortices and the erroneous temperature distribution near droplet triple-phase line disappear. (iii) If a special ghost fluid layer (as proposed in this paper) is constructed on the wall when the PP scheme or the MP scheme (primitive pseudopotential-based scheme or the modified pseudopotential-based scheme) is implemented, the instability of the numerical solution is improved, the deformation of droplet interface shape and the Marangoni vortices shape are corrected, and the unphysical vortices near the heated substrate and the erroneous temperature distribution near droplet triple-phase line disappear. The addition of such a special kind of ghost fluid layer at the heated wa
The curve interface reconstruction algorithm has received significant attention in the context of two-dimensional two-phase flow. However, it remains absent in the three-dimensional scenario. This paper proposes a nov...
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Plate fuel elements are commonly used in compact nuclear reactors due to the advantages of high fuel consumption. In this paper, the two-phase flow pattern in the coolant channel of plate fuel elements, i.e. the recta...
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More green and environmentally friendly electricity production is the driving force for the development of thermoelectric generators. In addition to high-performance thermoelectric materials, optimizing the geometric ...
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The thermionic conversion performance of the single-cell thermionic fuel element (TFE) is influenced by fuel mass transfer and other parameters. With the consideration of current flow and heat transfer, the thermionic...
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