FEM modeling of softened base metal in narrow-gap joint by CMT+P MIX welding procedure

A required finite element method（FEM） model applicable for narrow gap CMT and CMT＋P MIX welding was established based on the interactions between arc,base metal and filler metal.A novel method of simplifying wire feeding pulses and heat input pulses was supposed under the conduction of equivalent input.The method together with composed double-ellipse heat sources was included in the model.The model was employed in the investigation of thermal cycling and the identification of the softened zone of AA7A52 base plates.Low-frequency behavior emerged in the form of low-cooling rate sects,which were not expected under experimental conditions.The softened zone including the quenched zone and averaging zone of the base plate was much wider internal the base plate than that close to the surfaces.The reliability of the predictions in thermal cycling was supported by infrared imaging test results of the thermal cycle process.

整车涂装生产线中电泳加电问题的分析及探讨

在电泳涂装加电原理和结构的基础上，对实际生产过程中出现的带电入槽问题进行了详尽的分析，并通过多次实验和研究，总结出一套解决方案。

电泳涂装热入问题解决的技术探讨

电泳涂装的加电方式按照入槽状态可分为热入和冷入两种,以冷入方式投产时,常存在有个别工件热入现象,经分析试验和研究,得到问题的解决办法。

Radical treatment of stage Ⅳ pancreatic cancer by the combination of cryosurgery and iodine-125 seed implantation

AIM:To investigate the therapeutic effect of radical treatment and palliative treatment in stage Ⅳ pancreatic cancer patients.METHODS:81 patients were enrolled in the study.Radical treatment was performed on 51 patients,while 30 patients were put under palliative treatment.The procedural safety and interval survival for stage Ⅳ pancreatic cancer(IS-Ⅳ) was assessed by almost 2.5 years of follow-ups.The IS-Ⅳ of patients under the two kinds of treatment,and the effects of treatment timing and frequency on IS-Ⅳ,were compared.RESULTS:The IS-Ⅳ of patients who received radical treatment was significantly longer than those who received palliative treatment(P < 0.001).The IS-Ⅳ of patients who received delayed radical or palliative treatment was longer than those who received accordingly timely treatment(P = 0.0034 and 0.0415,respectively).Multiple treatments can play an important role in improving the IS-Ⅳ of patients who received radical treatment(P = 0.0389),but not for those who received palliative treatment(P = 0.99).CONCLUSION:The effect of radical treatment was significantly more obvious than that of palliative treatment,and multiple radical treatments may contribute more to patients than a single radical treatment.

Bone integration properties of antibacterial biomimetic porous titanium implants

A novel antibacterial biomimetic porous titanium implant with good osseointegration was prepared by freeze-casting and thermal oxidation.Bone integration properties of the porous titanium implant were evaluated by cell proliferation assay,alkaline phosphatase activity assay,X-ray examination and hard bone tissue biopsy.The in vitro cell proliferation and the level of differentiation of the group with a modified nano-porous implant surface were significantly higher than those in the group without surface modification and the dense titanium control group(P<0.05).In vivo,bone growth and osteogenesis were found in the experimental groups with modified and unmodified porous titanium implants;osteoblasts in the modified group had more mature differentiation in the pores compared to the unmodified group.Such implants can form solid,biologically compatible bone grafts with bone tissues,exhibiting good osseointegration.

Analysis of Film-Boiling Heat Transfer on a High Temperature Sphere Immersed into Liquid Sodium

Film-boiling heat transfer is a key phenomenon governing severe accident sequence in a sodium-cooled fast reactor. Experimental the fuel-coolant interaction process which may occur during a and theoretical work on film-boiling heat transfer in sodium has hardly been carried out in the past. An experiment has been conducted in the early seventies to investigate sodium pool boiling. In this experiment, a hot tantalum sphere was immersed into subcooled liquid sodium. Film boiling was obtained for various sets of parameters： sodium subcooling from 4.1 K to 29. 1 K, initial sphere temperature ranging from 1,802.6 K to 2,633.7 K, sphere diameters of 1.27, 1.91 and 2.54 cm and sodium depths of 7.6 cm and 11.4 cm. In the present work, a simplified analysis based on the boundary layer theory is developed to describe pool film-boiling heat transfer on a hot sphere in liquid sodium. Two extreme cases are considered depending on sodium subcooling. In the case of high subcooling, most of the heat lost by the sphere is used to heat the sodium while for low subcooling, it is used to vaporize the liquid at the liquid-vapor interface. It will be shown that the scaling analysis predicts the heat fluxes within the order of magnitude when compared to the available experimental data. Besides, it allows an estimation of the contribution of these fluxes to the liquid heating and vaporization processes.

Estimation of Vapor Quality at Compressor Suction of Air Conditioner

To evaluate performance and reliability of an air conditioner, the states of its refrigerant in the refrigeration cycle need to be understood. Since the isentropic exponent of the next-generation refrigerant R32 is larger than that of conventional refrigerant R410A, the compressor discharge temperature of R32 is higher than that of R410A. When a wet refrigerant is entered into a compressor suction line to decrease the discharge temperature, it is generally difficult to estimate the vapor quality at the suction. This paper describes a method that estimates a vapor quality at the compressor suction by applying energy balances on the compressor with the values of suction pressure, discharge pressure, discharge temperature, etc. In the air conditioner test, the vapor qualities at the compressor suction estimated with this method agreed well with those estimated with the conventional method by measuring liquid and vapor flow-rates. Moreover, this paper derived a relational expression for estimating a compressor suction state from a discharge state and discusses the characteristics of the coefficients in the expression calculated from the test results.

Multi-objective optimization of cooling air distribution of grate cooler with different inlet temperatures by using genetic algorithm

The paper discussed a multi-objective optimization model of the cooling air distribution of a grate cooler according to the analogy

Turbine Endwall Film Cooling With Combustor-Turbine Interface Gap Leak- age Flow: Effect of Incidence Angle

This paper is focused on the film cooling performance of combustor-turbine leakage flow at off-design condition. The influence of incidence angle on film cooling effectiveness on first-stage vane endwall with combustor-turbine interface slot is studied. A baseline slot configuration is tested in a low speed four-blade cascade comprising a large-scale model of the GE-E 3 Nozzle Guide Vane (NGV). The slot has a forward expansion angle of 30 deg. to the endwall surface. The Reynolds number based on the axial chord and inlet velocity of the free-stream flow is 3.5 × 10 5 and the testing is done in a four-blade cascade with low Mach number condition (0.1 at the inlet). The blowing ratio of the coolant through the interface gap varies from M = 0.1 to M = 0.3, while the blowing ratio varies from M = 0.7 to M = 1.3 for the endwall film cooling holes. The film-cooling effectiveness distributions are obtained using the pressure sensitive paint (PSP) technique. The results show that with an increasing blowing ratio the film-cooling effectiveness increases on the endwall. As the incidence angle varies from i = +10 deg. to i = 10 deg., at low blowing ratio, the averaged film-cooling effectiveness changes slightly near the leading edge suction side area. The case of i = +10 deg. has better film-cooling performance at the downstream part of this region where the axial chord is between 0.15 and 0.25. However, the disadvantage of positive incidence appears when the blowing ratio increases, especially at the upstream part of near suction side region where the axial chord is between 0 and 0.15. On the main passage endwall surface, as the incidence angle changes from i = +10 deg. to i = 10 deg., the averaged film-cooling effectiveness changes slightly and the negative incidence appears to be more effective for the downstream part film cooling of the endwall surface where the axial chord is between 0.6 and 0.8.

Effect of Nozzle Inlet Shape on Annular Swirling Flow with Non-Equilibrium Condensation

Recently,by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic flow,a separating and extracting techniques of condensate gas have been developed.This technique can reduce the size of the device and don't use chemicals.In the present study,by using a non-equilibrium condensation phenomenon of moist air occurred in the supersonic flow in the annular nozzle composed of an inher body and an outer nozzle with a swirl,the possibility of separation of the condensable gas and the effect of shape of nozzle inlet on the flow field were examined numerically.

Development of an aero-thermal coupled through-flow method for cooled turbines

The influence of complicated interaction between the flow field and heat transfer in cooled turbines becomes more and more significant with the increasing turbine inlet temperature. However, classical through-flow methods did not take into account the influence of the interaction caused by air cooling. The aerodynamic design and cooling design of cooled turbines were carried out separately, and the iterations between the aerodynamic design and cooling design led to a long design period and raised the design cost. To shorten the design period and decrease the design cost, this paper proposes a concise aero-thermal coupled through-flow method for the design of cooled turbines, taking into account the influence of the complicated interaction between the flow field and heat transfer in cooled turbines. The governing equations, such as energy equation and continuity equation in classical through-flow method are re-derived theoretically by considering the historical influence of cooling with the same method that deals with viscous losses in this paper. A cooling model is developed in this method. The cooled blade is split into a number of heat transfer elements, and the heat transfer is studied element by element along both the span and the chord in detail. This paper applies the method in the design of a two-stage axial turbine, of which the first stator is cooled with convective cooling. With the prescribed blade temperature limitation and the knowledge of the flow variables of the mainstream at the turbine inlet, such as the total pressure, total temperature and mass flow rate, the convergence of the calculation is then obtained and the properties of the flow field, velocity triangles and coolant requirement are well predicted. The calculated results prove that the aero-thermal coupled through-flow method is a reliable tool for flow analysis and coolant requirement prediction in the design of cooled turbines.

Effects of Chemical Reaction Caused by Cooling Stream on Film Cooling Effectiveness

With the increase of inlet temperature of gas turbines, the benefits by using the conventional methods are likely to approach their limits. Therefore, it is essential to study novel film cooling methods for surpassing these current limits. Based on the theory of heat transfer enhancement, a film cooling method with chemical reaction by cool- ing stream is proposed. In order to test the feasibility of the proposed method, numerical simulations have been conducted. The classic flat plate structure with a 30 degree hole is used for the simulation. In the present study, the effects of the parameters in relation to the chemical reaction on film cooling effectiveness, such as chemical heat sink, volume changes, and reaction rate, are investigated numerically. The conventional film cooling is also calculated for the comparison. The results show that film cooling effectiveness is improved obviously due to the chemical reaction, and the reaction heat and reaction rate of cooling stream have an important effect on film ef- fectiveness. However, the effect of volume changes can be ignored.