涡轮增压器设计培训资料.ppt

Cummins Global Brand Affect of turbine control on compressor operation Creating efficiency vs flow characteristics效率与流量的关系 Actual Dynamometer maps – 56% to 218% nozzle gap (expressed as % of turbine wheel tip width) 实际的测功图-喷嘴间隙由56%到218%，这个百分比是喷嘴间隙与涡轮顶部宽度的比值 Closing 逐渐关闭 Fully open 全开 Creating peak efficiency vs flow data for a given expansion ratio: 针对给定的膨胀比，做最大效率VS流量图 For each expansion ration, select the peak efficiency value and the speed/flow value at which it occurs 对于每一个膨胀比，找出最高效率值，以及对应的速度/流量值 Single Entry vs Twin Flow Turbines: Guidelines for Decisions 单流道VS双流道涡壳 Single entry turbine gives about 1 percent bsfc advantage at rated speed conditions. (About 3 – 4 % points turbine efficiency increase) Twin entry turbine gives about 1 percent bsfc advantage at peak torque conditions. Twin entry turbine gives better transient load pickup. Twin entry turbine not suitable when wastegate flows become large. 额定转速时，单流道涡壳在燃油消耗率方面有1%的优势（涡轮效率要高出3到4 个百分点） 最大扭矩时，双流道涡壳在燃油消耗率方面有1%的优势 双流道涡壳不适于旁通流量大的时候 双流道涡壳对瞬时负载增大有更好的响应能力 Cyl 1 Intake Manifold Exhaust Manifold Cyl 2 Cyl 3 Cyl 4 Cyl 5 Cyl 6 Comp. Turb. STACK AMB Wastegated Turbocharger Cooler After- Wastegate 旁通阀增压器 旁通阀 进气歧管 中冷 排气歧管 排气管(堆栈) 涡轮 压气机 Typically may need more boost here e.g. To reduce smoke at low engine speeds 通常是通过提高增压压力来降低发动机低速运转时的烟尘 Use smaller turbine casing to give more work to the compressor hence more boost! 小的涡壳,提供更多的功给压气机从而提高增压压力 Now, because housing is smaller, boost will also increase across the speed range of the engine 现在，由于涡壳小了,在发动机转速由最低上升到最大的过程中增压压力不断升高 Small casing to suit low flow at low engine speeds give too much boost at high flow high engine speed, thus leading to over speed 小的涡壳适宜于发动机低速、小流量的状态,但当发动机转速高、流量大时，由于压力上升过大, 会导致发动机超速. BANG! Small casing also means that engine will have too much boost at even less than max engine speed – too much boost can exceed peak cylinder pressure limits! 小的涡壳使发动机在尚未达到最大转速时，增压压力就已经很大了，甚至会超出气缸可承受的压力极限 Wastegate is set to open at a