Applied Mechanics and Materials Vols. 291-294

Abstract: Biomass alternative fuels have been around the world attention. This paper studies the characteristics of bio-diesel, bio-diesel by analyzing the physical, chemical properties, comparative bio-diesel and military advantages and disadvantages of diesel fuel come to bio-diesel is a diesel engine available in alternative fuels. In order to verify the heavy-duty off-road vehicles and light army vessel used biodiesel economy, power and reliability, we use the MAN-B & W6L20(27) diesel engine on the practical application of bio-diesel experiment results showed that: the security, power, oil consumption, emissions and reliability of all the available fuel to reach the target, it can be used as a safe alternative fuel use in diesel engines.

Abstract: Effects of EGR on the performance of bio-diesel engine were studied on a single-cylinder bench. The results showed that EGR can reduce NOx emission and NOx reduction increased with EGR rate. When EGR increases too much, due to the deterioration of combustion, CO and HC emission increased distinctly. When the EGR rate is lower than 25%, CO, HC and PM emissions increasing is tolerable, which means that 25% EGR rate can be used to improve NOx emission of bio-diesel engine.

Abstract: An experimental study was conducted on the combustion processes and emissions of direct coal liquefaction (DDCL) and Fischer-Tropsch (FT) fuels in a single-cylinder research diesel engine. Under low load conditions (5 bar IMEP), the results show that the ignition delay is shorter for the FT fuel compared with the reference fuel (Euro IV diesel), while it is longer for the DDCL fuel compared with the reference fuel. However, under high load conditions (10-15 bar IMEP), the Cetane number (CN) shows insignificant effects on the combustion process. The premixed heat release peaks of the fuels are correlated with the ignition delays, i.e. shorter ignition delay led to lower premixed heat release peak. For the emissions, both the FT fuel and the DDCL fuel show similar NOx level to the reference fuel under the conditions tested. The two liquefaction fuels show significantly lower soot emissions than the reference fuel, specifically for the higher load conditions (>=10bar IMEP), and the FT fuel produced the lowest level of soot emissions among the three fuels. For the FT and DDCL fuels, the HC emissions are generally lower than those of the reference fuel, except for the lowest load condition, which DDCL produces slightly higher HC emission. However, the CO emission of FT is lower than the reference fuel while the CO emission of DDCL is higher. In terms of unregulated emissions, the two liquefaction fuels show insignificant difference compared with the reference fuel at very low levels.

Abstract: The KIVA-3V program was used to make numerical simulation for L21/31 type of medium-speed marine diesel engine about the NOx emissions and the affection of NOx changing process on different variable parameters under the Tier Ⅱstandard. On this basis, a discussion towards the NOx emission of the model fueling with dimethyl ether (DME) to meet the Tier Ⅲ standard is offered. The results show that reducing the intake temperature, load and speed, postponing the fuel injection timing and intake lag angle properly can decrease the NOx emissions within the limits of NOx in TierⅡ standard. Comparing the results of the numerical simulation of DME and diesel fuel, the NOx emission of the former one is 60.85% of the latter one, and the NOx emission of changing variable parameters on DME engine is 35.56% of the original type of diesel engine, very close to the Tier Ⅲ.

Abstract: Building an engine cooling system model by GT-cool to analyze the fuel consumption of vehicle cold start in the low temperature environment stage.Getting the relationship between fuel consumption of vehicle cold start and the temperature of cooling water by model calculation.Providing a basis for optimizing the design of the engine cooling system.

Abstract: Experimental research was performed to describe the pressure drop occurring in horizontal taper pipe of dense phase pneumatic conveying, which were widely used in the engineering project. Compressed air was used as transmission power and fly ash as the transport medium. Results showed that the geometric parameters of taper pipe including taper angle and diameter ratio had a dominant effect on the pressure drop of the gas solid flow. In addition, a three-dimensional numerical simulation was performed to show the trend of the pressure field intuitively in the transporting process. And the simulation results of pressure drop were validated by the experimental data.

Abstract: This thesis put forward a hydraulic wave simulation system based on valve-controlled cylinder hydraulic system, which simulated wave movement on the land. The mathematical model of valve-controlled symmetric cylinder was deduced and the mathematical models of servo valve, displacement sensor and servo amplifier were established according to the schematic diagram of the hydraulic system designed, on the basis of which the mathematical model of hydraulic wave simulation system was obtained. Then the stability of the system was analyzed. The results indicated that the system was reliable.

Abstract: The combination of transverse injection and cavity flame stabilizer is a good way to improve the mixing efficiency and flame stability. In order to study the influence of transverse injection on the flow field of cavity in advanced vortex combustor, the turbulence flow and the fuel distribution under the influence of different assignments of jet holes were simulated numerically. The results show that the different assignments of jet holes have a bigger impact on the geometry and center of vortex, but lesser on the total pressure of combustor. The content of fuel reduces quickly in the jet direction, injection can improve the mixing of fuel and air. The phenomenon of mass diffusion and transport is obvious, it is in favor of flame stability.

Abstract: The resistance loss of pipeline is one of the main factors in wet-ash transportation system design, and it has a big influence on the economy of the wet-ash transportation. Based on a lot of experimental results, the multi-factor analyzing method on main factors such as flux, velocity, the diameter of pipe, slurry concentration, and slurry specific gravity that influence resistance loss of wet-ash transportation system was employed to find the degree of impact factor on resistance loss. These contents can be referenced in wet-ash transportation system design later.

Abstract: The interactions between waves and the pendulum wave power converter were simulated, considering Navier-Stokes (N-S) equations as governing equations of the fluid, using the k-ε turbulence model and finite element software ADINA. The setting wave-generating boundary method and viscosity damping region method were developed in the numerical wave tank. Nodal velocities were applied on each layer of the inflow boundary in the setting wave-generating boundary method. The viscosity of the fluid in the damping region was obtained artificially in the viscosity damping region method, and the energy in the fluid was decreased by the viscosity in governing equations. The physical model tests were simulated with the fluid-structure interaction (FSI) numerical model. The numerical results were compared with the experimental data, and then the results were discussed. A reference method is advanced to design the pendulum wave power converter. The method to solve the complex FSI problems is explored.