基于VGT控制参数的柴油机低速变海拔热平衡试验

Experimental Study on Thermal Balance of Diesel Engine at low speed affected by VGT Control Parameters at Variable Altitudes

中文关键词: 二级可调增压柴油机  低速  VGT叶片开度  高海拔  热平衡

英文关键词: regulated two-stage turbocharged engine  low speed  VGT vane opening  high altitude  thermal balance

中文摘要:

      进行二级可调增压柴油机热平衡性能研究,有助于解决高海拔发动机开锅问题,提高热效率。利用自主设计的柴油机高海拔热平衡试验系统,进行不同模拟海拔(0m、3500m、5500m)基于可变截面涡轮增压器(VGT)控制参数的二级可调增压柴油机低速全负荷热平衡试验,全面分析了变海拔条件下VGT控制参数对整机低速热平衡性能影响的机理与规律,优化标定了不同海拔下柴油机低速最佳VGT叶片开度。结果表明：随VGT叶片开度增大,发动机低速工况下热负荷升高,表现形式为涡前排温升高、缸内最高燃烧温度上升,但缸内最大燃烧压力呈下降趋势,0m、VGT开度小于50%时,缸内最高燃烧压力明显大于17MPa,在0、3500、5500m海拔,VGT开度分别大于70%、50%、30%时,缸内最高燃烧温度超过2200℃。随VGT叶片开度增大,柴油机有效功率、排气带走热量及其占比升高,冷却液带走热量、余项损失及其占比呈下降趋势,5500m 海拔下,VGT 叶片开度每增大10%,柴油机热效率降低3.1%。综合考虑VGT控制参数对缸内最高燃烧温度、缸内最大燃烧压力及热效率的影响,0m、3500m、5500m柴油机低速工况最佳VGT叶片开度应分别为50%、20%、20%。

英文摘要:

      The research on thermal balance performance of two-stage turbocharged(RTST) diesel engine is helpful to solve the problem of coolant boiling and improve thermal efficiency at high altitudes. The full load thermal balance test of RTST diesel engine with low speed at different simulated altitude (0m, 3500m and 5500m) based on variable geometry turbocharger (VGT) control parameters was carried out on the high altitude thermal balance test system for diesel engine. The influence of the VGT control parameters on the thermal balance of the diesel engine with low speed at variable altitudes was analyzed comprehensively, and the optimal openings of VGT vane at different altitudes was calibrated. The results show that with the increase of VGT vane opening, the heat load of the engine at low speed rises, which show that the exhaust temperature and the maximum combustion temperature in the cylinder increase, but the maximum combustion pressure in the cylinder decreases. When the opening of VGT vane at 0m is less than 50%, the maximum combustion pressure in cylinder is obviously greater than 17MPa. At the altitude of 0, 3500 and 5500m, when the opening of VGT vane is greater than 70%, 50% and 30%, the maximum combustion temperature in the cylinder exceeds 2200℃. With the increase of the VGT vane opening, the effective power of the diesel engine, the exhausting heat and the proortion them increase, while the heat taken away by coolant, the remainder heat loss and the proportion of them show a downward trend. At 5500m altitude, the thermal efficiency of diesel engine at low speed decreases by 3.1% with the opening of VGT vane increases by 10%. The influence of VGT control parameters on maximum combustion temperature, maximum combustion pressure and thermal efficiency in cylinder are considered comprehensively, for 0m, 3500m and 5500m, the best VGT vane opening at low speed should be 50%, 20% and 20% respectively.