内燃机原理中英文课件

内燃机学
Internal combustion engine fundamentals
第1章—绪论
Chaper 1 Introduction
课程内容：内燃机工作过程基础理论+内燃机总体及主要零部件结构course content: internal-combustion engine operating process fundation theory+general and main parts structure of it.
学时：64
academic period:64
第1章概论Chaper 1
Chaper 1 introduction
热机：（化学能燃烧机械能）heat engine: (chemical energy combustion mechanical energy)
外燃机：燃料在气缸外燃烧，加热工质做功。

external combustion engin: burning fuels outside the engine, and heating working fluids to work.
内燃机：燃料在气缸内燃烧，加热工质做功。

包括：往复式和其它形式。

往复式主要包括：压燃式，如柴油机和点燃式如汽油机，是本课程主要内容。

internal combustion engine: burning fuel inside the engine, and heating working fluids to work. Including: reciprocating engine and others. The reciprocating engine mainly including: compression-ignition engine such as diesel engine and
spark-ignition engine such as gasoline engine. Both of them are the main content of the course.
历史发展：
historical perspective
1860年莱诺依尔大气压力式的内燃机（没有压缩行程）
Nicolaus atmospheric engine (without compression cycle)
1876年奥托4冲程点燃式内燃机
Otto four-stroke spark-ignition engine
1890年本茨2冲程点燃式内燃机
Benze two-stroke spark-ignition engine
1892年狄塞尔4冲程压燃式内燃机
Diesel four-stroke compression-ignition engine 1902年雷诺机械增压
Renault mechanically supercharging
1915年波希涡轮增压器
bocy turbocharger
内燃机相对其它动力的优点：Advantage of the internal combustion compares with other power.
a. 结构简单；
b. 效率较高；
c. 重量体积比小；
a.simple structure
b.higher efficiency
c.less specific weight and specific volume
d. 成本低，使用方便，技术成熟。

d. low cost, operating convenient, mature technology
内燃机分类：
classification of internal combustion engine
图1-01
figure1-01
典型内燃机结构：structure of typical engine:
点燃式发动机：spark-ignition engine
图1-02、图1-03、图1-04、图1-05 figure1-02 figure1-03 figure1-04 figure1-05
压燃式发动机：compression-ignition engine
图1-06、图1-07 figure 1-06 figure 1-07
内燃机学
Internal combustion engine fundamentals
第2章—内燃机工作指标
Cheap 2 Engine Operating Parameters
内燃机工作指标包括：
engine operating parameters including:
动力性（功率、转速、扭距）、运转性（冷启动、排气品质）、耐久可靠性（大修时间）、经济性（燃料和润滑油消耗率）。

Power performance (power、speed、torque)、operation performance (cold start、quality of exhaust)、durable reliability(interval between Overhaul)、economy(specific fuel consumption and lube oil consumption rate)
2．1 示功图指示性能指标
2.1 indicator diagram indicator performance parameters
示功图
indicator diagram
4冲程内燃机p-φ示功图—图2-01
figure2-01 p-φdiagram for four-storks engine
4冲程内燃机p-V示功图—图2-02
figure 2-02 p-V diagram for four-storks engine
p-φ和p-V有一一对应关系，可以相互转换。

方法：用途：
p-φis one to one correspondence with p-V，Conversing Each Other. method : use:
指示性能指标：以工质对活塞做功为基础的指标，反映燃烧过程的特征。

indicator performance parameters: the parameters that basic on working fluids pushing the piston to work reflect the characteristic of combustion process
1．指示功和平均指示压力
indicated work and mean indicated pressure
指示功W i：气缸内完成一个工作循环得到的有用功
indicated work Wi: obtained available work per cycle in the cylinder.
发动机的p-V图—图2-03
figure 2-03 p-V diagram of engien
平均指示压力p mi：单位气缸容积一个工作循环所做的指示功；或一个假想的作用在活塞上的不变的压力，使活塞在一个冲程的位移中做的循环指示功。

Mean indicated pressure p mi: obtained indicated work with unit cylinder volume per cycle; or obtained cycle indicated work at a piston stroke with an imaginary invariable pressure to the piston
用途：application
2．指示功率indicated power
指示功率P i：单位时间做的指示功W i indicated power Pi: indicated work Wi in unit time
3．指示热效率和指示燃油消耗率
indicated thermal efficiency and indicated specific fuel consumption
指示热效率ηit：发动机指示功与消耗燃料热量的比值
indicated thermal efficiencyηit: rate of indicated work of engine to the heating of consumption fuel
指示燃油消耗率b i：单位指示功的耗油量
indicated specific fuel consumption b i:Fuel Consumption for unit indicated work.
2．2 有效性能指标
effective performance parameters
有效性能指标：指示性能指标扣除摩擦及附件消耗。

反映的是发动机的真正做功能力。

effective performance parameters: indicated performance parameters without friction and consumption of accessory. A measure of an engine’s ability to work veritably
1. 机械效率和有效功率mechanical efficiency and brake(useful) power
有效功率：P e =P i-P m brake(useful) power: P e =P i-P m
机械效率：ηm= P e/ P i mechanical efficiency: ηm= P e/ P i
内燃机有效功率：brake(useful) power of engine:
推导：Derivation
2. 平均有效压力和升功率mean effective pressure and power per liter
平均有效压力p me：单位气缸容积一个工作循环所做的有效功, 或一个假象的作用在活塞上的不变的压力，使活塞在一个冲程的位移中做的功为循环有效功。

Mean indicated pressure p me : obtained effective work with unit cylinder volume per cycle; or obtained cycle effective work at a piston stroke with an imaginary invariable pressure to the piston
升功率power per liter
3、充量系数和过量空气系数Charging Coefficient and excess air coefficient
冲量系数：实际循环进气量与进气管状态下充满气缸的空气量比值。

Charging Coefficient: rate of real cycle intake mass to air capacity full of cylinder in the air inlet pipe states
过量空气系数φa：燃烧单位燃料的实际供给空气量与理论空气量之比。

excess air coefficientφa: rate of practical to theoretical air mass provided for burning unit fuel
柴油机：φa=1.2 – 2.2 汽油机φa=0.85 – 1.1
diesel engine : φa=1.2 – 2.2 gasoline engine: φa=0.85 – 1.1
空燃比：空气与燃料的比值。

Air/fuel ratio: rate of air to fuel.
4．有效热效率和有效燃油消耗率effective thermal efficiency and brake specific fuel consumption
有效热效率：ηet=W e / Q1 effective thermal efficiency : ηet=W e / Q1有效燃油消耗率：单位有效功的耗油量。

brake specific fuel consumption: Fuel Consumption for unit brake work
2．3 机械损失与机械效率
mechanical loss and mechanical efficiency
平均机械损失压力：p m =p i-p e mean mechanical loss pressure: p m =p i-p e
机械损失的主要组成：mechanical loss mainly including:
1．活塞和活塞环的摩擦损失：45-65% friction loss of piston and piston ring: 45-65%
2．轴承与气门机构的摩擦损失：2-3% friction loss of bearing and valve train: 2-3%
3．附件的功率消耗：10-20%。

只包括必不可少的附件：油水泵等，不包括：水箱风扇，空气压缩机、空调等。

power consumption of accessory: 10-20% only including accessory that is indispensable: pumps for oil or water etc not including: fan for water tank、air compressor
4．驱动扫气泵和增压器的损失：10-20% loss of driving scavenging pump and supercharger
机械损失的测定mensuration for mechanical loss
1．示功图法indicator diagram test method
上止点位置不容易精确得到（<0.5°）。

the location of TDC(top dead center) is not easy to find accurately
2．倒拖法
motoring test method
需要电力测功机。

误差有：气缸不能燃烧带来的压力、温度变化，影响到摩擦功。

Electrical Dynamometer is needed. The error including: pressure and temperature variety due to not burning in the cylinder, influencing friction work.
3．灭缸法
extinguish spark of the cylinder test method.
必须是多缸机。

分别对某一气缸停机，减少制动力矩直到转速恢复，得到此时的功率，则摩擦功率为：P-P’。

叠加各缸，得到整机的摩擦功。

It must be multi-cylinder engine. Stop the engine for each cylinder to reduce the Brake Torque until the speed retrieve, then the power obtained is friction power. Superposition the each cylinder’s can get the friction work for the whole engine.
4．油耗线法
Fuel Consumption Curve test Method
多用于柴油机或喷射式汽油机。

在固定转速下进行负荷特性试验，得燃
油消耗量与平均有效压力的关系曲线：
Generally used in diesel engine or injection gasoline engine. Get relation curve of fuel consumption and mean effective pressure from the load characteristic experiments at fixed speeds
图2-04
figure 2-04
P me为0时所消耗的油量B为克服摩擦功所用。

延长油耗曲线，得到摩擦功。

P me is the fuel consumption B for overcoming friction work at point 0. Get the friction work by prolonging curve of fuel consumption.
2．4 提高内燃机动力性与经济性的途径
the path for improving Power performance and economy of engine
1．采用增压技术：use supercharging technology
2．合理组织燃烧过程，提高指示效率：organize reasonably burning process to improve indicated efficiency
3．改善换气过程，提高气缸冲量系数：
Ameliorate exchange process to improve Charging Coefficient 4．提高发动机转速：improve the speed of engine
5．提高机械效率：Improve the mechanical efficiency of the engine.
内燃机学
Internal combustion engine fundamentals
第3章—内燃机的工作循环
Cheap 3 Engine Operating Cycles
3．1 内燃机的理论循环
Theoretical cycle of engine
内燃机的实际热力循环：燃料的热能转变为机械能的过程
The actual thermodynamic cycle of engine :the process that thermal energy of fuel changes into the mechanical energy
内燃机的理论循环：将实际循环简化，忽略次要因素，得到便于进行定量分析的假想简化循环
theoretical cycle of engine: obtain imaginary predigestion cycle ignoring secondary factor that is easy to do quantitative analysis with actual predigestion cycle
理论循环的简化假设：the simplifying assumptions of the theoretical cycle
1．空气为工质，为理想气体。

其物理化学性能不变，比热为定值；The working fluids are air which can be treated as ideal gas. Physical and chemical performances keep constant, so does the specific heat.
2.工质的总质量不变，忽略了流动损失；
The mass of the working fluids is constant ignoring flow loss 3．工作过程绝热；
Operating cycle is adiabatic
4．用假想的加热放热代替实际的燃烧与排气过程，排气过程视为等容放热过程。

Replace actual combustion and exhaust processes with
imaginary heating and exothermic. Treat exhaust process as constant-volume exothermic process.
研究理论循环的目的：
the objective of studying on theoretical cycle.
1．阐明热力循环参数间的关系；elucidate the relation among the thermodynamic cycle parameters.
2．确定循环热效率的极限；determine the limit of thermal efficiency of cycle
3．分析比较不同循环方式的经济性和动力性。

analyze and compare economy and dynamic performance among different circulating mode
根据不同的燃烧方式，典型的内燃机理论循环有3种：等容加热、等压加热、混合加热。

there are three typical engine theoretical cycle according as different combustion mode: constant-volume combustion 、constant-pressure combustion、limited-pressure combustion. 典型的理论示功图—图3-01
Typical pressure-volume theoretica diagram figure 3-01
压缩比：V a/V c，压力升高比p z/p c
: V a/V c , pressure elevation ratio: p z/p c
各种理论循环的特点：
the characteristics of various theoretical cycle
等容加热：加热在等容条件下很快完成，点燃式发动机；
constant-volume combustion: heated rapidly in
constant-volume condition such as SI engines
等压加热：加热在等压条件下缓慢完成，燃气轮机、早期压燃式发动机；
constant-pressure combustion: heated slowly in
constant-pressure condition such as gas turbine、former CI engine.
混合加热：先在等容条件下很快加热，然后在等压条件下缓慢完成的压燃式发动机。

limited-pressure combustion: first heated rapidly in
constant-volume condition then slowly in constant-pressure condition as CI engine
初始状态及加热量一致，当压缩比相同时，等容加热效率最高；当循环最高压力相同时，等压加热效率最高。

when the Initial State and calefaction heat quantity are consistent, the constant-volume combustion efficiency is the highest with the same compression ratio, while with the same circulation highest pressure is constant-pressure combustion.
各种理论循环比较的结论：
conclusion for comparing all kinds of various theoretical cycle 1．提高压缩比，可以提高工质最高温度，从而提高了热效率；Raise thermal efficiency though increasing compression ratio to increase the highest temperature of the working fluids.
2．提高压力升高比可以提高混合加热中等容部分的比例，从而提高了热效率；
Raise thermal efficiency though increasing pressure elevation ratio to increase the constant-volume parts in the
limited-pressure.
3．绝热指数k增加，热效率增加。

Raise thermal efficiency though increasing adiabatic exponent k
内燃机实际工作条件的约束和限制：
constraint and limitation for internal combustion in actual operation:
1．结构条件：强度及可靠性。

structure conditions: intension and reliability
2．机械效率：摩擦功增加。

Mechanical efficiency: Friction Power increased
3．燃烧：爆燃,余隙太小，燃烧室设计困难。

Combustion: Deflagration, too small clearance volume, design hardly for combustion chamber.
3．2 内燃机的燃料
the fuel for internal combustion engine
1．石油燃料petroleum
成分：碳-氢化合物占97-98% component: CH 97-98%
炼制方法：Refining method
直接蒸馏法：质量较好direct distillation: better quality
热裂解法：质量较差hot dehiscing: worse quality
催化裂解法：质量最好atalytic pyrolysis method: best quality
柴油和汽油的理化性质：physicochemical properties of the diesel and gasoline
柴油：diesel
1.自燃温度：十六烷值autoignition temperature: cetane number
2.低温流动性：柴油标号（凝点）0号、-20号等low temperature
fluidity : diesel labeling (freezing point) number 0 , number-20 etc.
汽油：gasoline
1.挥发性volatile
2.抗爆性：辛烷值：马达法、研究法antiknock ability: octane number: method of motor 、method of research
2. 气体燃料gas fuel
1．天然气：热值较低nature gas :lower calorific value
2．液化石油气LPG (liquefied petroleum gas)
排放较好，可替代汽油replace gasoline for better emission
3. 代用燃料Alteraative Fuel
1．醇类（甲、乙）alcohol (methanol, ethanol)
2．植物油vegetable oil
排放较好，可替代柴油replace diesel for better emission
3.3 内燃机的实际循环
engine actual cycle
非增压柴油机理论循环和实际循环p-V图—图3-02
P-V diagram figure3-02 for not supercharging diesel theoretical and actual cycles
与理论循环的差异：
difference between theoretical and actual cycles
1．不同工质影响：非理想的双原子气体、成分不断变化，影响到比热（增加），从而降低了最高循环温度。

Effect by different working fluids:specific heat influenced due to
the component of nonideal diatomic gas changes constantly and reduces the highest cycle temperature.
2．换气损失：包括排气门提前打开、流动阻力损失。

Gas exchange loss: including exhaust valve opened ahead, flowing resistance loses
3．传热损失：非绝热过程。

Heat Transfer Loss: nonadiabatic process
4．燃烧损失：包括燃烧的速度限制（引起压缩负功增加、最高压力下降）、后燃及不完全燃烧。

combustion loss: including the limited speed for burning (increase minus compression work and reduce the highest pressure), after-burning and incomplete combustion
3．4 内燃机循环的热力学模型
thermodynamic model of engine cycles
燃烧模型：combustion model
1．热力学模型（0维模型）thermodynamic model (dimensional model)
2．现象学模型（准维模型、分区模型）phenomenological model (quasi-dimensional model, partition model)
3．多维模型multidimensional model
热力学模型的假定：hypothesis of thermodynamic model 1．气缸内为单区过程；single zone process in the cylinder
2．工质为理想气体；ideal gas for working fluids
3．气体流动为稳定流动，不计动能；gas flows steadily ignoring
kinetic energy
4．进、排气系统的压力和温度波动不计；the pressure and temperature of the inlet and exhaust system is ignored
5．工质无泄露。

working fluids do not let out
热力过程计算图—图3-03 the diagram for thermodynamic process account
控制方程：control equation
公式相应项计算：corresponding items account of the equation 1．气缸工作容积：cylinder displacement:
4．放热率：heat release rate:
热力过程计算中的简化：
The predigestion for thermodynamic process account
1．闭式阶段：无质量、能量交换
Closed phase : no mess and enery exchange
2．开式阶段：进排气过程计算
opened stage: inlet and exhaust account
进排气过程的计算：inlet and exhaust process account
1．容积法volumetric method
2．特征线法characteristic method
3．差分法（高维）difference method (high dimensional)
内燃机循环模拟计算结果：
calculation results of engine cycle simulation
图3-04 figure 3-04
内燃机学
internal combustion engine fundamentals
第4章—内燃机的充量转换
Cheaper 4 Engine Exchange Processes
第4章内燃机的冲量转换
Cheaper 4 Engine Exchange Processes
冲量转换：排气门（排气口）开启到进气门（进气口）关闭的整个过程。

冲量转换的状态与系统设计和运行状态有关。

Gas exchange processes: the whole from exhaust valve (exhaust port) opened to inlet valve (inlet port) closed. The state of gas exchange processes is related with system design and operation state.
4．1 4冲程内燃机的换气过程
gas exchange processes for four-strokes engine
1．自由排气阶段free exhaust phase
超临界状态：气缸压力远大于排气管压力，流速为当地声速，流量取决于缸内状态和气门开启有效截面，与排气管内状态无关。

supercritical state: The pressure in the cylinder is much higher than in exhaust pipe. velocity is local velocity of sound, and the flow is depended on gas state in the cylinder and valve opening effective section not relating with the state in the exhaust pipe. 亚临界状态：气缸压力和排气管压力比较接近，流量与有效截面和缸内与排气管内压差有关。

排气提前：减少废气推出功
subcritical state: the pressure in the cylinder is almost equal with
in the exhaust pipe. The flow is related with valve opening effective section and different pressure between in the cylinder and exhaust pipe. If the exhaust is advanced, that will reduce gas pushing work.
自由排气阶段排出的废气量与内燃机的转速无关，但在高速时相同的排气时间对应着更大的曲轴转角。

exhaust volume during free exhaust stage do not relate with the engine speed, but in the high speed crank angle is larger with the same exhaust time.
2．强制排气阶段forced exhaust phase
活塞上行推动排气the piston upgoing pushes the exhaust gas. 排气迟闭：非增压-利用废气引射；增压-安排扫气过程
exhaust valve close later : not supercharging –make use of exhaust ejecting; supercharging –arrange the scavenging process.
3．进气阶段intake phase
进气提前：保证进气过程开始时有适当的进气流通截面
Intake advanced: ensure proper intake flow area at the beginning 进气迟闭：非增压-利用惯性进一步充气；增压-安排扫气过程
intake closed later: not supercharging –make use of inertia for more charge
换气损失：
gas exchange loss
1．排气损失exhaust loss
包括：膨胀损失（由于排气门提前开启）和推出损失（活塞推出废气）Including : expansion loss ( due to exhaust valve opening
advanced) and pushing loss ( the piston pushes exhaust gas)
与排气提前角的关系：排气提前角增大，膨胀损失增大，推出损失减小The relation with advance angle: expansion loss increases and the pushing loss decreases as the exhaust advance angle gets larger
与转速的关系：转速增加，膨胀损失略有增加，推出损失有较大增加 the relation with the speed: as the speed increases , the expansion loss increases slightly while the pushing loss increases more.
转速对排气损失的影响—图4-01
the speed for influencing exhaust loss
2．进气损失inlet loss
包括：进气消耗的功和进气量的损失（均由于流阻）
Including: consumption work of inlet and the loss of intake flow rate ( all is due to flow resistance)
泵气损失：由排气损失和进气损失组成
pumping loss: consist of exhaust and inlet loss
提高冲量系数的措施：
measures for improving the charging coefficient
1．降低进气阻力reduce the intake resistance
包括：including
降低进气门阻力：增加进气门数量、增加进气门直径（进、排气门不等径）等
reduce the intake resistance: increase the inlet valve and the diameter of valve(the diameter of inlet and exhaust valves are
not equal) etc
图4-02
figure 4-02
采用可变进气系统：可变凸轮机构、可变气门定时
adopt Variable Intake System:variable cam mechanism , variable valve timing(VVT)
2．降低排气阻力reduce the exhaust resistance
采用适当的排气系统adopt proper exhaust system
3．减少冲量温度reduce charging temperature
中冷intercooling
4．2 内燃机增压
supercharging for engine
增压的目的：得到更多的空气，从而可以提供更多燃料，得到更大功率。

The purpose for supercharging: obtain more power though getting more air and fuel
包括：增压器、增压器与内燃机的匹配、内燃机增压后的调整
including: supercharger, the matching between supercharging and engine, adjustment after supercharging
1．增压对经济性和动力性的影响
Supercharging influencing for economy and Power performance 增压效果直接取决于增压比和压气机绝热效率
the effect of the supercharging depend on pressure ratio and adiabatic efficiency of the compressor
增压性能估算：
estimate supercharging performance
根据压气机绝热效率的计算公式，得增压前后温度的变化：T b/T0
get temperature variation after supercharging according as calculation formula the compressor’s adiabatic efficiency
T b/T0
且压气机绝热效率越高，温升越小。

根据气体状态方程，得增压前后密度的变化：ρb/ρ0
Temperature rise less as the adiabatic efficiency is higher. Get density variation after supercharging according as gas state equation
ρb/ρ0
和冲量系数的变化（也可以省略）：and charging coefficient variation ( it can be ignored)
φb/φ0
则有增压前后平均指示压力的变化: mean indicated pressure after supercharging variation:
p b/p0
和机械效率的变化：mechanical efficiency variation:
ηb/η0
于是得有效功率和燃油消耗率的变化：so obtain the effective power and specific fuel consumption variation
P b/P0 b b/ b 0
增压对经济性和动力性都有较大的益处。

Supercharging is more benefit for the economy and Power performance
增压优势与代价Advantages and Disadvantages of supercharging
优势：Advantages
1．大幅度提高功率increase greatly engine power output 2．节省制造材料save making material
3．降低排气噪声decrease the exhaust noise
4．有利于高原恢复功率recover profitably power in the Plateau 5．排放总体下降reduce the whole emission
6．适用范围广泛apply at wide range
代价：Disadvantages
1．机械及热负荷增加increase mechanical and thermal load 2．低速扭矩受影响influence the torque at low speed
3．响应性差poor responsiveness
2．增压方式supercharging method
增压方式包括：机械、涡轮、气波、复合等。

supercharging method including :mechanical supercharging ,turbocharging ,pressure wave supercharging, mixture supercharging
图4-03
figure 4-03
排气涡轮增压exhaust turbocharging
排气涡轮增压器（涡轮）包括：径流式增压器和轴流式增压器，压气机通常为离心式。

exhaust turbocharging (turbo) including: Radial-flow and Axial-Flow supercharging and compressor generally is Centrifugal.
径流式增压器用于高转速及响应性好的场合，如车用发动机；Radial-flow supercharging is used in the high speed and well responsiveness condition, such as vehicle engine
轴流式增压器用于大流量、高效率的场合，如大型发动机。

Axial-Flow supercharging is used in large flow and high efficiency coditon, such as large-scale engine
图4-03-2
figure 4-03-02
离心式压气机工作过程Radial-flow compressor operation processes
图4-04 figure 4-04
压气机的主要作用是提高气体压力，即增加气体密度。

其工作过程见上图，为：
the main function of the compressor is improving the gas pressure just the density. The operating processes is showed in the upper diagram.
压气机特性曲线characteristic curve of compressor
主要特性参数包括绝热效率、压比、流量、转速。

见图4-05。

The main
Characteristic Parameters includes adiabatic efficiency, pressure ratio, flow rate and speed, as figure 4-05
各特性参数分析：
each Characteristic Parameters analysis
喘振与阻塞surge and obstruction
喘振：当压气机工作在喘振线左侧时，压气机工作不稳定甚至强烈振动，发生危险。

原因：当流量太小、压比太大时，工作轮进口处的气流与壁面发生分离现象。

Surge: when the compressor operates on the left of the surge line, the compressor is unstable or even shaking intensively that will be danger. Causation: when the flow is too large and the pressure is to high, airflow of operating impeller in the inlet separate with wall
阻塞：压气机工作在特性线右下侧时，流量太小、压比太大。

当压比继续降低时，流量也不增加，即阻塞现象。

Obstruction: when the compressor operates on the underside right of the Characteristic line with too small flow and too high pressure, the flow would not increase as the pressure ratio falls continuously that is the choking phenomenon.
压气机通用特性曲线（去除大气环境的影响）general characteristic curve of compressor (except influenced by the atmospheric environment)
折合流量：reduced flow rate
折合转速：corrected speed
径流式涡轮工作过程Radial-flow Turbine operating processes
径流式涡轮工作简图—图4-05-2 the diagram for Radial-flow Turbine operation –figure 4-05-2
径流式涡轮的结构设计的核心是将压力和温度降低，转化为动能并将其传递给涡轮。

The design core of radial-flow Turbine is reducing the pressure and temperature, then the heat energy translate into kinetic energy transferring to the turbo.
4．3涡轮增压系统
turbo supercharging system
定压系统与脉冲系统—图4-06
pressure fixing system and pulse system- figure 4-06
定压系统：系统介绍。

优点：涡轮在定压下全周进气，效率高，系统结构简单。

缺点：脉冲能量利用率低，流动损失大，响应差，扫气效果差。

pressure fixing system: introduction system. Advantage: intake gas all the while in the fixing pressure, with high efficiency and simple system structure. Disadvantage:low the utilization efficiency for pulse energy, great flow loss, bad response, poor scavenging effect.
脉冲系统：图4-07。

系统介绍。

优点：脉冲能量利用率高，流动损失小，响应好，扫气效果好。

缺点：涡轮间歇进气，效率低，系统结构复杂。

pulse system: figure 4-07. introduction system. Advantage: high the utilization efficiency for pulse energy, little flow loss, well response, well scavenging effect. Disadvantage: intake gas
intermittently, low efficiency, complex system structure.
脉冲转换器：图4-08。

系统介绍。

优点：能量传递优于定压系统，涡轮效率优于脉冲系统。

缺点：结构复杂，能量形式多次转换，有损失。

pulse converter: figure 4-08. introduction system. Advantage: energy transfer is better than pressure fixing system, turbine efficiency is higher than pulse system. Disadvantage: complex system structure, the energy multiple conversion with energy loss
多脉冲系统：图4-09。

系统介绍。

用于多缸。

即可以保证能量传递效率，又可以提高涡轮效率。

multi-pulse system: figure 4-09. introduction system. Using for multi-cylinder engine. It can not only improve the efficiency of energy conversion, but also the turbo efficiency.
模块式脉冲转换（MPC）系统：图4-10。

系统介绍。

结构简单，能量传递效率和涡轮效率都高。

module pulse conversion(MPC) system: figure4-10. introduction system. With simple structure, both the efficiency of energy conversion and turbo are high.
各种脉冲系统特点比较：图4-10。

Comparing the characteristic of various pulse system .figure 4-10
涡轮增压器与发动机的匹配
match a turbocharger to an engine.
增压器的选择：增压压力、流量、效率the choice for supercharging: the ratio of supercharging, flow and efficiency
压气机：增压压力、流量compressor : the ratio of supercharging and flow
涡轮：功率平衡turbo: power balance
增压后发动机的调整adjustment after supercharging for engine
1．压缩比：降低。

降低机械负荷。

compression ratio: reduce the compression ratio to decrease the mechanical load
2．过量空气系数：升高。

降低热负荷，降低油耗。

excess air coefficient: increase the excess air coefficient to reduce heat load and oil consumption.
3．供油系统fuel injection system
4．配气机构：气门重叠角加大。

valve train: increase valve overlap angle
5．进、排气系统：进气系统容量加大；排气系统重新设计。

Inlet and exhaust system: increase the inlet capability ; design the exhaust system again.
6．中间冷却：进一步增加功率，降低油耗，降低排放。

Intercooling: increase power further, reduce the oil consumption and emission.
汽油机增压supercharging for gasoline
主要制约因素：爆燃。

混合气形成使用喷射方式。

通常为低增压。

对于车用要求增压器响应性好。

main limited factor: deflagration. Make use of injection to form mixture gas. The supercharger which request well respond generally increases pressure low.
机械增压mechanical supercharging
特点：响应性好；功率、油耗的收益较少；结构紧凑。

Characteristic: well respond ; less benefit for power and oil consumption; compact structure
4．3 二冲程内燃机的换气
two-stroke engine exchange
二冲程内燃机的换气过程： two-stroke engine exchange process 特点：characteristic
1．自由排气阶段free exhaust stage
气体流出约70-80%。

Exhaust about 70-80%
2．强制排气阶段forced exhaust stage
活塞上行推动排气the piston upgoing pushes the exhaust gas. 3．过后排气或过后进气阶段exhaust aferwards or inlet afterwords stage
多数二冲程内燃机的扫气口的关闭早于排气口。

Most two-strokes engine scavenging port closed is earler than exhaust port
过后排气：可以进一步排出废气exhaust afterwords : exhaust more exhaust gas
过后进气：可以额外充气（少部分二冲程内燃机）
二冲程内燃机换气过程的特点the characteristic for two-stroke engine exchange process
1．时间短；in short time
2．排气、进气同时进行inlet and exhaust gas simultaneously
二冲程内燃机的换气方案（图4-12、图4-13）exchaner method
for two-strokes engine exchange
横流扫气cross-scavenged
回流扫气loop-scavenged
直流扫气uniflow-scavenged
曲轴箱扫气crankcase scavenging
内燃机学
internal combustion engine fundamentions
第5章—内燃机混合气的形成和燃烧
Cheaper 5 – Engine Mixture Generation And Combustion
内燃机混合气的形成和燃烧影响着发动机的动力性、经济性、噪声和排放。

engine mixture generation and combustion influences the power performance, economy, noise and emission.
5．1 内燃机缸内的气体流动
the air flow inside cylinder
良好的缸内气体流动，对汽油机可以：提高火焰传播速度、降低燃烧循环变动、适应稀燃烧或层燃的需要等；对柴油机可以：提高混合气形成速度、提高燃烧速度、促进热混合作用等。

Well air flow inside cylinder, for the gasoline, increasing the speed of flame spread, reducing Combustion Cyclic Variations, adapting the requirements of Lean or Stratified Combustion; for diesel engine, increasing the mixing speed, rising burning velocity, promoting fuel evaporating and mixing with air by the high temperature.
1．进气涡流：绕气缸轴线的有组织的气体流动。

intake swirl: organized rotation of the charge about the cylinder axis
分布：小于某一半径时，涡流沿半径增加而增加，即刚体分布；大于某一半径时，涡流沿半径增加而减少，即势流分布。

接近上止点时，势流减弱，可以认为是刚体分布。

进气涡流可以持续到燃烧结束。

distribution:when it is less than a certain radius, the tangential speed of the swirl increases as the radius increasing that is
rigid-body distribution; but when it is greater than a certain radius, the tangential speed of the swirl reduces as the radius increasing that is potential flow distribution. It can be treated as rigid-body distribution because of potential flow decreasing nearby TDC. The intake swirl may continued to t the end combustion.
形成：1. 带导气屏的进气门 2. 切向气道 3. 螺旋气道
generation: 1.intake valve with guide gas panel 2. tangential intake port 3.Helical Intake Duct
进气涡流的形成—图5-01
the generation of intake swirl – figure 5-01
产生涡流的气道的气流速度分布图5-02
velocity profile of generating swirl airway
气道的评定：流动阻力涡流强度
evaluation of the airway: flow resistance swirl intensity
2．挤流squish flow
挤流：压缩过程后期，由于活塞与气缸盖彼此靠近挤压形成的气体流动。

挤流在汽油机上得到了广泛的应用。

squish flow: the squish flow generates due to the piston closing to the cylinder head squeezing the gas flow at the compression later. The squish flow is used widely in the
gasoline.
3．滚流（横轴涡流）tumble swirl ( cross-axis swirl)
进气滚流：由于进气过程产生的垂直于气缸轴线的有组织的气体流动。

intake tumble swirl: organized perpendicular of the charge about the cylinder axis generated due to intake process.
滚流发展过程图5-03
the development process of tumble swirl
4．湍流turbulence
湍流：气缸内的无规则的气体流动。

其特征通常用统计方法加以定义。

重要用于汽油机。

Turbulence: ruleless gas flow inside the cylinder. Generally, it is defined with statistical method for character. It is mainly used for gasoline.
5．2 点燃式内燃机的燃烧
the combustion of SI engine
1．着火过程与着火落后
Ignition Process and ignition lag
火花点火过程the process of spark ignition
火花点火过程十分复杂，有许多方面还有待研究。

大体分为：
the process of spark ignition is very complex, and further study is needed. Mainly divided into:
1．击穿阶段：高压电离，击穿breakdown phase:high voltage ionization, breakdown
2．电弧：建立电流通道，形成电弧electric arc: build current chunnel to form electric arc
3．辉光放电：绝大部分点火能量在此阶段放出glow discharge: let。