Air-flow Simulation And Analysis On Cooling System Of All-terrain Crane

Air-flow Simulation and Analysis on Cooling System of All-terrain CraneThe complexity of the engine compartment internal structure of all-terrain crane determines that the traditional design process of the engineering equipment is difficult to test and analysis the flow and cooling process of the engine compartment internal and external simultaneously.Now, computational fluid dynamics (CFD), which widely used, less restricted, with short cycle and low cost, access to information detailed, and obtain a large number of tests and interpretation information that difficult to obtain by the current test, re-emergences with the development of computer technology. Using the mature theory and software related to CFD to study the flow and cooling issues inside and outside the all-terrain crane engine compartment has become the effective method and means.A type of all-terrain crane engine cooling system researched in this paper failed to achieve pre-design requirements in actual use, include that the radiator and intercooler dose not play the expected cooling effect, with the high engine cooling water temperature and the high intake air temperature. For dealing with the poor cooling effect of the cooling system, this paper explores possible factors impacting the flow and heat transfer process inside and outside the engine compartment, and proposed possible improvements for the engine cooling system ultimately.The studies of this Paper include:1) To describe the heat transfer research content, including methods and procedures of the numerical simulation of flow and heat transfer, discrete methods and equations solution involved in the numerical process, etc.2) To establish a simplified model of air flow in a type of all-terrain crane cooling system. Using grid construction method, the model was meshed and refined. The boundary conditions and related physical parameters of simulation were defined by experimental data. Based on the experimental data and empirical formula, the radiator module, fan model and engine compartment model parameters were fitted equations to obtain the simulation parameters of these models.3) In order to verify the correctness of simulation program, simplified model of the cooling system was established. By the experimental data, parameters of the module were set, the control conditions for solving and convergence criteria were determined, and then the simulation results were analyzed and compared with the experimental results. The results show that comparing simulation results with experimental values and theoretical values, the relative ratio of the differences between them is within the allowable range. The theories and simulation methods used in this paper are reliable and credible.4) First, the simplified model established of air flow field of a certain type all-terrain crane cooling system was simulated. The velocity, temperature and flow distribution of the channel in the flow field were analyzed in detail, and the heat transfer law of cooling air outside the heat sink module was learned. In order to obtain factors about thermal performance of the coupling flow field inside and outside the cooling system, this paper explores the mechanism of ambient temperature, fan speed and the vehicle speed on the vehicle model and the radiator module. With the ambient temperature reducing, the most significant effect on radiator module is that cooling fluid outlet temperature decreases. With the fan speed increasing, the cooling air flow through the radiator module increases, and heat transfer power also increases. When the speed faster, the velocity of the cooling air into the engine compartment by the bottom becomes faster, heat transfer is more effective, but thermal reflow also increases.5) The engine compartment enormous impacts on the smooth degree of cooling air flow, the degree of cooling air into the engine compartment and mixing with thermal reflow, the radiator cooling air inlet temperature distribution and thermal reflow in the engine compartment, and these factors also directly determine heat transfer capacity of the engine cooling system, particularly the heat transfer performance of radiator. With the increase of the distance between cab and the radiator module, heat transfer power of radiator module increases, but when the spacing increases in a larger range, the heat transfer power dose not increase significantly. The final improve program opened holes in the top and sides of the engine compartment and increased a certain distance in front of the radiator module. Simulation results show that this program optimizes air flow conditions in the engine compartment, improves the cooling effect of the radiator module, and improves heat transfer performance of the cooling system.