Papers by Author: Qian Wang

Abstract: Intake port is an important part of the gasoline engine, its structure will influence the gas flow characteristics which directly affects the performance of the engine [1]. In this paper, three-dimensional CFD calculation and structural optimization were used to research the performance of gasoline engine. Firstly, the method of laser scanning and UG software were used to reverse modeling engine exhaust port and get the three-dimensional model. Secondly, after setting boundary conditions and turbulence models, the air flowing through the intake ports were simulated by FLUENT software respectively. Finally, based on numerical methods, the pressure field, velocity field were shown. The results of the simulation of flow field characteristics analysis show that the simulation and experimental results are in good agreement.

Abstract: The performance of the engine air intake system directly affect the working performance and fuel consumption, where the intake manifold design is the key.In this paper aimed at L91 Engine intake manifold ,firstly theRE(Reverse Engineering)technology was usedto rebuild the3d model of intake manifold.And then the internal flow zoneof the intake manifoldwas meshedin the pre-processing software ICEMand the internal flow fieldwas analyzedin the softwareof Fluent.The numerical model was verified by comparing the simulated and measured results. And then based on the numerical analysis of the internal flow characteristics of the intake manifold, the structure of variable-length intake manifold was come up with and finally was numerically proved to be better than the normal one.

Abstract: Experimental study on macroscopic spray characteristics of a certain type of domestic common rail injectors under the conditions of different injection pressures was carried out through a high-speed digital camera. Furthermore, a fuel dripping phenomenon at the end stage of injection was observed through the high-speed digital camera equipped with a long-distance microscope, and a further analysis of the phenomenon was made. The results show the increase in the injection pressure can evidently enhance spray cone angle and expand the scope of spray field in combustion chamber, which is conducive to air-fuel mixture. The spray cone angle during the development spray shows a double-peak shape. And the long response-time of seating of solenoid valve core that disables the injection cutting off in time is one of factors causing fuel dripping phenomenon.

Abstract: Numerical simulation of the combustion and emissions of HPDI engine under different natural gas substitution rate was performed using AVL FIRE . The effects of natural gas substitution rate on cylinder average pressure, temperature, heat release rate, NO and Soot were analyzed under four typical conditions. Cylinder average pressure and temperature decrease with increasing natural gas substitution rate. Furthermore, the NO emission will decrease significantly under the same circumstances.

Abstract: Water spray cooling is widely used in many industrial processes to control heat removal from a hot material surface. In this work, pressurized spray nozzle was applied to break film boiling immediately once the quenching process is started. For this purpose, a circular disc made of non-ferrous metals is heated to approximately 850 °C and sprayed on one side by hydraulic nozzle and the temperature distribution with respect to time and space is measured by using Infrared camera. On the other side, the measured surface was coated with graphite paint in order to achieve a high emissivity. By this IR thermography, transient temperature measurement can be carried out within the window of 320 × 80 pixels. The heat transfer was analyzed through 1D method. In this method, the temperature difference between both sides neglected. The local heat transfer can then be calculated from a simple differential energy balance.

Abstract: Based on the KIVA-3V source program and coupling the multidimensional model of in-cylinder combustion, this thesis designs a simulation platform of the combustion and emission performances of diesel engines. Results of the test on the in-cylinder pressure change and emission of the experimental subject proves the accuracy of the platform, showing that the platform is able to objectively reflect the real working process of the subject, and that it can be used to research the combustion and emission performances of the experimental engines for a further improvement of the working performances.

Abstract: As a study of natural gas engine, three-dimensional numerical simulations of diesel injection rates were conducted by using AVL FIRE code. And particularly the effects of the injection rates in the pilot diesel jets on the engine combustion and emission were analyzed. It is found that injection rate in the pilot diesel jets plays an important role on the emission, and slow ending rate of the injection keeps lower NO and Soot.

Abstract: The visualization experimental setup of micro free-piston engine has been built, the process of single shot compression combustion in micro combustion chamber has been observed by the high-speed digital camera; Based on the propane combustion kinetics, the numerical calculation method for combustion process coupling with the free-piston movement was put forward, through editing the dynamic mesh subroutine in STAR-CD, the process of homogeneous charge compression ignition (HCCI) in the micro chamber was studied; The influence of piston initial state on HCCI combustion process was analyzed , indicating that the piston mass directly affects the homogeneous gas compression ratio, ignition time, single combustion process cycle and the changes of combustion pressure and temperature, all this research can be the basic theories for designing the micro free piston engine .

Abstract: A greenhouse heating mode was proposed in this paper in order to reduce energy consumption and increase the efficiency of heating system for greenhouse. Considering experimental greenhouse practical operating conditions and various environmental factors, a warm air heating system, with heat source of biomass boilers, end heat abstractor of fan coils, was designed and some winter heating experiments was conducted. With the CFD method, the modelling of thermal environment inside the greenhouse in winter night was realized, temperature variation and distribution was simulated by STAR-CCM+. The simulation results were compared with experimental temperatures at the key positions in the greenhouse, and indicated that temperature errors of the monitoring points were less than 2K, relative error less than 8%, calculated root-mean-square error was 0.47K. Thus the validity of proposed model was certified.

Abstract: A three-dimensional Urea-SCR catalytic converter model was simulated with the method of CFD coupled with chemical reaction dynamic in this paper. With the modeling of urea solution injection and spray, the urea spray angle was optimized to reduce the urea wallfilm on the pipe wall. The flow fields and component distributions of a full scale Urea-SCR catalyst system were obtained to analyze the flow and chemical reaction characteristic of SCR system. Finally, an SCR system with a simple blade SCR mixer was simulated, the results indicated that the mixer can accelerate the evaporation and thermolysis of urea solution, and improve reductant uniformity and NOx conversion efficiency of Urea-SCR system.