Papers by Keyword: Transition

Abstract: A coupled heat transfer (CHT) solver was established. The solver couples the N-S equations with the heat conduction equation using the finite volume method. The developed CHT solver was verified by Mark II 5411 case. The numerical results agree well with experimental data, proving the accuracy of the developed CHT code. The solver was applied to the coupled heat transfer simulations of an air-cooled turbine with a single cooling channel. Adiabatic results and CHT results were compared. Different turbulence and transition models were employed. The result shows that the developed code is of great use in engineering simulations, and in order to predict thermal loads on turbine vane accurately, transition needs to be considered.

Abstract: In recent years Unmanned Aerial Vehicles (UAV) has become a significant segment of the aviation industry. They can be chosen to be designed as fixed wing or Rotary wing type. Fixed-wing aircraft has the performance of fast forward movement, long range and superior endurance due to its gliding capabilities with no power. Unlike the fixed wing models, rotary wing mini-copters are able to fly in all directions, hover in a fixed position with minimal space for takeoff and landing. This makes them the perfect instrument for detailed inspection work or surveying. Implementing a hybrid UAV has the advantages of both fixed-wing and rotary wing UAV. This paper aims to brief on the design, development and testing of a hybrid tilt body UAV with four rotors. The hybrid vehicle comprises two units, an aerial unit and a ground unit. The aerial unit consists of an unmanned aircraft system. The ground unit consists of means to view and post-data processing of video/image sent by the UAV if it is used for aerial surveillance and control, navigate and guide the aircraft. To proceed, a novel hybrid UAV with capability of Vertical Take Off and Landing (VTOL) and horizontal flight is developed and its response during the transition from VTOL to horizontal flight is analyzed.

Abstract: The turbulent flow inside contra-rotating disk cavity was numerically studied based on the finite volume method. The flow structure and its transition characteristics inside a contra-rotating were studied. The flow structure varies with the angular velocity ratio Γ of the slower disk to that of the faster one. For Γ=-1, the Stewartson-type flow occurs throughout the domain. For Γ=0, the Batchelor-type flow occurs throughout the flow region. The stagnation streamlines originating from the stagnation point are formed for-1<Γ<0, and batchelor-type flow occurs radially outward of the stagnation point with Stewartson-type flow radially inward. The stagnation point moves radially outward as Γ is reduced.

Abstract: Graphite growth morphology was studied by using InLense detector on FEG-SEM after performing ion etching on the samples. Star like and circumferential growth mechanism of graphite was observed in the graphite nodules. Pure ternary alloy of hypo eutectic and hyper eutectic composition was treated with pure Mg, Ca and Sr, to study the effect of O and S concentration in the melt, on the transition of graphite morphology from nodular to vermicular/compacted and flake graphite. The change in the melt composition between the austenite dendrites due to micro-segregation of S, O and inoculants and their possible effects on the transition of graphite morphologies as well as the nucleation of new oxides/sulfides particles is discussed with the help of thermodynamics.

Abstract: The waste PE modified asphalt is a material with high added value and technical content. It is a new and optimal material for road construction. By adding waste PE into asphalt to improve the asphalt’s performance [1], a longer use age of the road, a lower level of noises, and a more improved driving comfort and safety can all be achieved [2]. This paper mainly focuses on measuring the primary indexes of several modified asphalt samples produced under different conditions [3]. Based on the test data, a scientific analysis will be conducted to confirm the optimal manufacturing conditions, therefore transform the theory of PE modified asphalt into practice.

Abstract: The fluid-structure interaction (FSI) method is employed to analyze heat transfer of a exhaust manifold with a water jacket. Three different turbulence models are valued to predict their spheres of application. The mutual effect on complex flow distribution and heat transfer with and without transition is also considered respectively. The results show that reasonable turbulence model and transition will contribute to a better numerical precision of temperature distribution. Considering transition will have a impact on the design of novel exhaust manifold of high speed gasoline engine. In addition, numerical results can be referred to improve the structure.

Abstract: The genetic algorithm was employed to Multidisciplinary Design Optimization of transonic internally cooled turbine blades based on the conjugate heat transfer (CHT) method. Firstly, a parametric modeling method was employed to model the internal-cooled blade.Comparison of the SST turbulence model with and withoutγ-θtransition model was conducted, and the influence and reason between turbulent region and heat transfer distribution was analyzed.The result shows that separation appeared after middle region of the suction surface, because of the pressure after shock wave decrease abruptly that reduce adverse pressure gradient resistance capacity of laminar flow, it leads to instability and transition, and then enter a state of turbulence, same to the heat transfer coefficient with the phenomenon of abrupt increase that impact the temperature distribution, consequently SST model with γ-θ transition is better to showcase the change of aerodynamic and heat transfer in the transition region; Then,comparing the cooling effectiveness with different number cooling holes of internal-cooled blade , four cooling channels case was the best choice in consideration of the cooling effectiveness and the manufacturing process and the cost of the blade; In the end, Automatic optimization process was set up ,andseveral optimization frameworks were achieved. With the cooling flow increase in 0.011849 kg/s, average temperature and maximum temperature were reduced by 4.92% and 1.55% respectively in the boundary conditionsoptimization, in addition to optimized the cooling flow and the cooling effectiveness, temperature distribution in the part of contrastive analysis of turbulence model was verifiable, Simultaneously it is important guiding significance for the geometry parameters optimization.

Abstract: The perfect moulding must have transition and echo, so "transition and echo" is the aesthetic principle that the moulding design of farm machineries have to observe. In some farm machinery products as an example,illustrates that the proper" transition" of products gives people lively, clever feeling, and has clear, certainly, soft beauty , and that reasonable " echo" of products gives people harmonious and unity feeling, and has friendly, movtion, open aesthetics characteristics.

Abstract: From the beginning in the Ming and Qing dynasties until the end of the republic of China, “Zou Xikou” immigration movement lasted more than three hundred years, and has changed the environment of Inner Mongolia. The migrants to the han nationality and the local Mongolian’ behavior all changed accordingly, their way of life and production, way of living has also changed accordingly. This change promoted the formation of the village and the city in Inner Mongolia, which is the miniature of current Inner Mongolia. This article discusses the environment and behavior transition under the influence of “Zou Xikou” immigration in Inner Mongolia. We study this transition from the historical background, production mode, population structure, and city building four angles. We also do the restitutive description, which is mainly aimed at grassland agriculture, population of localization, living centralization and regional architecture, in order to better explore the regionalism of Inner Mongolia.

Abstract: This study concerned the influence of the material strength, ductility and impact energy and the relationship of the broken section profile vs. ductile transition brittle where the steel material was treated under different tempering temperature and hardness. Generally after the steel materials, 10B35 coil wire materials which was generally applied to form screws, was treated by quenching and tempering, its hardness ranged from HRC30 to HRC45. The results showed that the elongation rate beyond 20.4% would be proportional to the impact energy with linear relation, but with reverse proportion to the hardness value. The brittle-tough point of the hardness was set around HRC37 after heat treatment in order to balance the strength and the toughness. In addition, the coil wire materials were analyzed from broken section materials showing good toughness; this represented that the area of the cross section radiation layer due to ductile fracture would largely increase. On the contrary, the wire material test fragment with bad toughness represented that the area of the shear layer due to brittle fracture would largely increase as well. As to that material, if its hardness was greater than or equal to HRC37, that material would have an excellent turning danger from transition. At the same time, when the tempering temperature of the wire steel material was set under 4600C and its corresponding central hardness was about HRC37, the distance between two cementite phase layers suddenly increased. This result leaded to the reason why the wire material test fragment was turned into brittleness from ductility. Therefore, when the fastener was manufactured under tempering treatment, avoiding the tempering brittleness temperature range was necessary.