热力与动力计算 课程设计版(1).doc

内燃机课程设计 -6S50MC柴油机标定工况热、动力计算院 系：机械工程学院班 级：热动07-3班姓 名：蒿 德 意学 号：0703120306原始参数及已知条件型 号 ： 6S50MC船用柴油机热计算气缸直径 ： 125mm活塞行程 ： 130主机转速 : 2500r/m缸 数 : I 8 压 缩 比 ： 18有效压缩比： 12小时功率： 每缸工作容积： 每缸余隙容积： 曲柄半径： 连杆长度 曲柄半径和连杆长度比： 大气状态： 和 燃料平均重量成分： （重柴油）燃料低热值： 燃烧室形式： 浅盆型，直接喷射式燃烧室扫气方式： 直流扫气一 6S50MC型柴油机热计算及结果(1)增压气参数的选择1）增压器出口空气压力 ：2）增压器压缩指数 ：（根据经验公式活塞式或离心式nk=1.4-1.8 ）3）增压后空气的温度 （2）压缩过程参数1）压缩始点压力 ： 由于本柴油机选用的是直流扫气 根据二冲程直流扫气的经验公式 ，取2）压缩终点温度 ： 1）残余废弃系数的选择。二冲程直流扫气fyr=0.03-0.12，由于此柴油机转速较低，有充分的时间进行扫气，因此取2）残余废气温度的选择。二冲程柴油机残余废气温度，由于此型号的柴油机低速，且具有超长行程，有充分的时间散热，因此取3）点热利用系数 ：4)空气进入气缸的温升, 系列柴油机由于具有中冷设备，空气的温度应该有所降低，因此取压缩终点温度 ：（3）有效压缩比 （4）充气系数：（5）平均压缩多变指数 。选取平均多变压力指数（低速增压活塞冷却柴油机一般在说明：压缩过程中气体得到热多越大，相反则越小。由此影响其取值的主要因素有如下几点：1） 发动机的构造特征，水冷发动机的主要零件（缸体、缸盖、活塞）温度要比风冷发动机的低，因此水冷的较小。2） S/D较小时，要比长冲程的机型小一些。3） 当气缸套、活塞、活塞环以及气门密封袋磨损时，漏气量增加，就会带走一部分热量，从而使减小。4）燃烧室表面积碳，会使零件温度升高，减少散热量，使升高。（6）压缩终点温度：（7）压缩终点压力：（8）压力升高比 ： 1）最高爆发压力：选取 （9）燃烧所需理论空气量： 1）：由于是低速柴油机 因此可以选用重柴油，减少燃油成本，以提高燃油经济性。重柴油 2）（10）燃烧所需实际空气量：1）过量空气系数。 高速增压额定工况的过量空气系数，一般均推荐1.62.0(直接喷射式)，选择的原因：过大，虽然燃烧充分肯定导致排风量过大，热损失也大；过小，势必燃烧不充分，燃烧不充分就影响效率。所以选择1.8。1）有利于燃烧过程迅速的完成，增加燃烧产物中二原子气体含量，可以获得较大的绝热压缩与膨胀指数，减少排气热损失，增加发动机经济型。2）在充气状态良好的情况下采用较大的过量空气系数，可以降低主要元件的热负荷，特别是活塞组的热负荷，有利于整机的可靠性和耐久性。3）较大的过量空气系数可以降低发动机的升功率和平均指示压力。2）（11）理论分子变化系数（12）实际分子变化系数（13）Z点烧去的燃油份数1） 低速柴油机的Z点的热利用系数。2）点的热利用系数。（14）Z点处分子变化系数（15）（16）为了求取17步值，以及24步 、25步的具体值，以便减少工作量，本文提供了一个循环体函数，用以下MATLAB代码可以求出（具体代码见附件，在此本文将不再进行重复计算 只带入数值）。通过循环可以得到，（17）z点燃烧产物的定容平均摩尔比热 ：（其中，的应带入）1）2） （18）b点燃烧产物的定容平均摩尔比热：（其中，的应带入 ）1） 2） （19）Z点b点燃烧产物的定容平均摩尔比热 ：（20）燃油发热量（）：（其中的应带入293）1）2） （21）求最高燃烧温度 （）：。（其 中的应带入 ，的应带入 ，的应带入 ）1）2）计算 1）2）3）3)计算1）2）3）4） 4）验证代入以上三步数值计算 得出（22）初期膨胀比（23）后期膨胀比 （24）平均膨胀多变指数1）计算1）2）（25）膨胀终点温度。验证成立（27）理论平均指示压力（以有效形程为准）：（28）实际平均指示压力（以全行程为准） （29）平均有效压力（30）指示油耗（31）有效油耗（32）指示效率（33）有效效率。（34）指示功率。（35）有效功率 。 二 、二冲程内燃机。 1)二冲程示功图的分析由下图可以看出 二冲程有以下四个过程组成。他们分别是扫气线，压缩线，燃烧线，膨胀线。下面对这几个过程分别进行分析。为了简化模型，在分析之前坐几点假设。一：压缩过程中 上止点附近，漏气量很少，或者漏气量相对于整个有效工作容积很小，可以忽略不计。二：由于本篇文章只考虑热计算，为了简化，假设扫气过程中，气门提前开启造成的气体损失很小，也不与考虑。 于是这四个阶段便可以用以下方程模拟出此段过程为扫气过程的一部分，此时气缸内部由于扫气孔的存在和扫气箱相连通，构成连通器，由连通器原理可知：气体压力此时由于扫气孔关闭，缸内气体为纯压缩过程，又因为压缩多变指数（由上文选取）。因此气体压力和体积满足下述方程。此方程过，代入解方程知，此段气体压力，此段过程设计到燃烧过程，由于燃烧时间极短，燃烧过程极为复杂，目前尚无比较完整的方法来进行模拟（或者能够模拟的方法也极为为复杂，已经超出本科生研究范围之内）。即使用测功器测出来的示功图（如图3.1）在这段也都需要修正（如图3.3），修正方法不一，而且也不是本科生的研究范围，本文不进行深加研究，但是介于以往的经验，本文提出可以做一个近似的模拟计算。即假设此段的压力和体积符合三角函数关系。通过matlab对 一份合格的图（图3.5）进行提取分析，验证之间的函数关系 得出以下结果。提取的六个点分别是xx = 0.0333 0.0342 0.0361 0.0383 0.0411 0.0424yy =1.0e+007 * 1.6016 1.6460 1.6746 1.6841 1.6810 1.6651分析后得到一下结果：General model Sin1: f(x) = a1*sin(b1*x+c1)Coefficients (with 95% confidence bounds): a1 = 1.692e+007 (1.671e+007, 1.714e+007) b1 = 54.93 (37.42, 72.45) c1 = 11.99 (11.35, 12.64)Goodness of fit: SSE（标准差）: 2.884e+010 R-square(方程的确定系数): 0.9406 Adjusted R-square（变量个数较多时看这个）: 0.901 RMSE（均方差）: 9.806e+004R square称为方程的确定系数，01之间，越接近1，表明方程的变量对y的解释能力越强R-square 与 Adjusted R-square一个意思，通常看第一个，反映线性化拟合的好坏。由此可以确定之间近似可以满足这个函数关系式图3.5：准确的图 图3.6：Matlab cftool 拟合分析图形上止点附近喷入燃油，燃油燃烧放热使气体膨胀。又因为膨胀多变指数 (热计算第26步)，因此此段的气体方程为，此方程过,带入方程解出知：气体压力，段活塞头经过扫气孔，此时扫气孔再次与外界相连通，由于存在气体的交换，此时气体的压力并不是突降成扫气箱进气压力的，而是近似的看作成一种线性的下降。即压强与体积近似满足一次函数关系。这种函数关系可以通过两个点求出。具体过程本文不再计算。P-V图数据（P（单位：Mpa） ，V(单位：L)）o-a1段a1-c段c-z段z-b段b-o段Vx1Px1Vx2Px2Vx3Px3Vx4Px4Vx5Px5420.35390.3388.82740.327.654910.361538.694614.361388.82740.7854419.26680.3376.37320.313428.035510.78150.768210.1409389.91450.7671418.17970.3363.91890.327828.416211.184362.84177.7155391.00160.7489417.09260.3351.46470.343528.796911.570674.91536.16392.08880.7306416.00550.3339.01050.360529.177611.939386.98885.0867393.17590.7124414.91830.3326.55630.37929.558312.2999.06234.3065394.2630.6941413.83120.3314.1020.399329.93912.6221111.13593.7165395.35010.6759412.74410.3301.64780.421630.319612.935123.20943.2565396.43730.6576411.6570.3289.19360.446130.700313.2284135.2832.8889397.52440.6393410.56980.3276.73940.473231.08113.5017147.35652.5892398.61150.6211409.48270.3264.28510.503331.461713.7545159.43012.3407399.69860.6028408.39560.3251.83090.536931.842413.9866171.50362.1317400.78570.5846407.30850.3239.37670.574732.22314.1974183.57711.9538401.87290.5663406.22140.3226.92250.617332.603714.3868195.65071.8007402.960.5481405.13420.3214.46820.665832.984414.5543207.72421.6677404.04710.5298404.04710.3202.0140.721433.365114.6998219.79781.5512405.13420.5116402.960.3189.55980.785633.745814.8231231.87131.4485406.22140.4933401.87290.3177.10560.860534.126414.9238243.94491.3573407.30850.4751400.78570.3164.65130.948934.507115.002256.01841.2759408.39560.4568399.69860.3152.19711.054334.887815.0575268.0921.2027409.48270.4386398.61150.3139.74291.182135.268515.0901280.16551.1367410.56980.4203397.52440.3127.28871.339635.649215.0999292.2391.0769411.6570.4021396.43730.3114.83441.537836.029915.0869304.31261.0225412.74410.3838395.35010.3102.38021.793536.410515.0509316.38610.9727413.83120.3656394.2630.389.9262.13436.791214.9922328.45970.9272414.91830.3473393.17590.377.47182.605837.171914.9108340.53320.8853416.00550.3291392.08880.365.01753.295637.552614.8068352.60680.8466417.09260.3108391.00160.352.56334.382137.933314.6803364.68030.8109418.17970.3389.91450.340.10916.295838.313914.5316376.75390.7777419.26680.3388.82740.327.654910.361538.694614.361388.82740.7469420.35390.3动力计算基本参数 ：发动机转速: 连 杆 比 ： 活塞组质量：1）活塞头质量： 2）活塞杆质量： 3）十字头质量： 总质量 ： 连杆组质量 ： （1）计算 1）时 2）对一般柴油机来说， 对一般船用和固定式发动机连杆小端质量 连杆大端质量 3）往复质量 （2）活塞的运动规律计算1）活塞位移 2）活塞速度 3）活塞加速度 附表2 运动分析数据表曲轴转角（度）活塞位移x（m）活塞速度（m/s）活塞加速度（m/s2）020-103.6708101.99-1.4428-104.5548201.9598-2.9087-106.8836301.9091-4.4118-109.7322401.8372-5.9502-111.7057501.7439-7.5004-111.1391601.6292-9.0152-106.3416701.4942-10.4255-95.854801.3407-11.6446-78.6863901.1723-12.5768-54.50641000.9935-13.1269-23.75221100.8101-13.211212.34521200.6292-12.768551.8351300.4583-11.768492.20891400.3051-10.2183130.63511500.177-8.1651164.2381600.0805-5.6944190.39161700.0204-2.9251206.992818000212.68321900.02042.925206.99322000.08055.6944190.39232100.1778.165164.23892200.305110.2182130.63622300.458311.768492.21012400.629212.768551.83622500.810113.211212.34642600.993413.1269-23.75122701.172312.5769-54.50562801.340711.6447-78.68572901.494210.4255-95.85353001.62929.0153-106.34143101.74397.5005-111.1393201.83725.9503-111.70573301.90914.4119-109.73233401.95982.9087-106.88363501.991.4429-104.554936020-103.6708（3）图转化为图其中fy为曲轴转角（单位：度）P为气体压力（单位：Mpa）fyPfyPfyP00.339.73220.3180.000210.36151.01880.343.32880.3064180.427710.36972.03750.346.92540.3136180.855210.39443.05630.350.5220.3218181.282710.43554.07510.354.11860.331181.710210.49285.09390.357.71530.3414182.137710.56596.11260.361.31190.3531182.565210.65477.13140.364.90850.3663182.992710.75868.15020.368.50510.3811183.420210.87729.1690.372.10170.3978183.847711.0110.18770.375.69830.4167184.275211.156111.20650.379.29490.438184.702711.31512.22530.382.89160.4622185.130211.485813.24410.386.48820.4897185.557711.667414.26280.390.08480.521185.985211.858915.28160.393.68140.5568186.412712.05916.30040.397.2780.5979186.840212.266617.31920.3100.87460.6451187.267712.480218.33790.3104.47120.6998187.695312.698319.35670.3108.06790.7633188.122812.919320.37550.3111.66450.8374188.550313.141521.39430.3115.26110.9245188.977813.362822.4130.3118.85771.0272189.405313.581423.43180.3122.45431.1491189.832813.79524.45060.3126.05091.2947190.260314.001425.46930.3129.64751.4698190.687814.198226.48810.3133.24421.6814191.115314.382827.50690.3136.84081.9386191.542814.552628.52570.3140.43742.253191.970314.704929.54440.3144.0342.6385192.397814.836830.56320.3147.63063.1118192.825314.945231.5820.3151.22723.6919193.252815.027332.60080.3154.82384.3971193.680315.079933.61950.3158.42055.2406194.107815.099934.63830.3162.01716.2203194.535315.084135.65710.3165.61377.304194.962815.029536.67590.3169.21038.4111195.390414.932937.69460.3172.80699.4038195.817914.791238.71340.3176.403510.1061196.245414.601639.73220.3180.000210.3615196.672914.3611fyPfyPfyP196.672914.3611320.270.7469348.450.3199.84212.4676320.990.766348.750.3203.011110.7673321.710.7471349.050.3206.18029.2855322.440.7284349.340.3209.34938.018323.160.7102349.640.3212.51846.9457323.880.6923349.930.3215.68756.0436324.60.6748350.230.3218.85665.286325.330.6577350.530.3222.02574.6496326.050.6409350.820.3225.19484.1137326.770.6245351.120.3228.36393.6611327.50.6085351.410.3231.5333.2772328.220.5928351.710.3234.70212.9502328.940.5775352.010.3237.87122.6705329.660.5626352.30.3241.04032.4302330.390.548352.60.3244.20942.2227331.110.5338352.890.3247.37852.0428331.830.5199353.190.3250.54761.8862332.550.5064353.490.3253.71671.7493333.280.4933353.780.3256.88581.62923340.4806354.080.3260.05491.5235334.720.4682354.380.3263.2241.4301335.450.4561354.670.3266.39311.3474336.170.4444354.970.3269.56221.2739336.890.4331355.260.3272.73131.2084337.610.4221355.560.3275.90041.1499338.340.4115355.860.3279.06951.0975339.060.4013356.150.3282.23861.0506339.780.3914356.450.3285.40771.0084340.50.3818356.740.3288.57680.9705341.230.3726357.040.3291.74590.9364341.950.3638357.340.3294.9150.9056342.670.3553357.630.3298.08410.8779343.390.3471357.930.3301.25320.8528344.120.3394358.220.3304.42230.8303344.840.3319358.520.3307.59140.8099345.560.3248358.820.3310.76050.7916346.290.3181359.110.3313.92960.7751347.010.3117359.410.3317.09870.7602347.730.3057359.70.3320.26780.7469348.450.33600.3（3）往复惯性力的计算 （MPa）fyfjfyfyfjfyfyfjfyfyfjfyfyfjfyfyfjfy0-2.065139.7322-1.2779180.00021.0066196.67291.0292320.2678-1.2779348.454-1.99161.0188-2.064543.3288-1.1481180.42771.0066199.8421.0374320.9905-1.3033348.75-1.99532.0375-2.062846.9254-1.0134180.85521.0067203.01111.0462321.7133-1.3284349.046-1.99893.0563-2.059950.522-0.8751181.28271.0068206.18021.0551322.436-1.3533349.342-2.00244.0751-2.055954.1186-0.7346181.71021.0069209.34931.0638323.1587-1.3778349.638-2.00585.0939-2.050757.7153-0.5931182.13771.007212.51841.0717323.8814-1.4021349.934-2.00916.1126-2.044461.3119-0.452182.56521.0072215.68751.0784324.6041-1.4261350.23-2.01237.1314-2.036964.9085-0.3124182.99271.0074218.85661.0834325.3269-1.4498350.526-2.01558.1502-2.028368.5051-0.1756183.42021.0076222.02571.0861326.0496-1.4731350.822-2.01859.169-2.018672.1017-0.0427183.84771.0079225.19481.0859326.7723-1.4961351.118-2.021410.1877-2.007875.69830.0852184.27521.0082228.36391.0824327.495-1.5188351.415-2.024311.2065-1.995879.29490.2074184.70271.0086231.5331.075328.2178-1.5412351.711-2.02713.2441-1.968786.48820.4312185.55771.0093237.87121.0467329.6632-1.5848352.303-2.032314.2628-1.953590.08480.5315185.98521.0098241.04031.0247330.3859-1.606352.599-2.034715.2816-1.937393.68140.6235186.41271.0102244.20940.9971331.1086-1.6268352.895-2.037116.3004-1.9297.2780.7068186.84021.0107247.37850.9634331.8314-1.6473353.191-2.039417.3192-1.9017100.87460.7813187.26771.0112250.54760.9233332.5541-1.6674353.487-2.041618.3379-1.8823104.47120.8469187.69531.0118253.71670.8767333.2768-1.687353.783-2.043619.3567-1.862108.06790.9038188.12281.0123256.88580.8232333.9995-1.7062354.079-2.045620.3755-1.8407111.66450.952188.55031.0129260.05490.7629334.7222-1.725354.375-2.047522.413-1.7952118.85771.0239189.40531.0142266.39310.6217336.1677-1.7613354.967-2.05123.4318-1.7711122.45431.0486189.83281.0149269.56220.5409336.8904-1.7788355.263-2.052624.4506-1.746126.05091.0665190.26031.0156272.73130.4537337.6131-1.7958355.559-2.054125.4693-1.7201129.64751.0783190.68781.0164275.90040.3602338.3358-1.8124355.855-2.055526.4881-1.6933133.24421.0846191.11531.0171279.06950.2608339.0586-1.8284356.151-2.056927.5069-1.6657136.84081.0864191.54281.0179282.23860.1561339.7813-1.844356.447-2.058128.5257-1.6373140.43741.0842191.97031.0188285.40770.0465340.504-1.8591356.743-2.059229.5444-1.608144.0341.0789192.39781.0196288.5768-0.0675341.2267-1.8738357.04-2.060231.582-1.5473151.22721.0622193.25281.0213294.915-0.3056342.6722-1.9015357.632-2.06232.6008-1.5159154.82381.0523193.68031.0222298.0841-0.4284343.3949-1.9146357.928-2.062734.6383-1.4509162.01711.0325194.53531.0241304.4223-0.6772344.8403-1.9393358.52-2.063935.6571-1.4175165.61371.0238194.96281.0251307.5914-0.8016345.5631-1.9508358.816-2.064336.6759-1.3834169.21031.0166195.39041.0261310.7605-0.9247346.2858-1.9618359.112-2.064737.6946-1.3488172.80691.0111195.81791.0271313.9296-1.0458347.0085-1.9723359.408-2.064938.7134-1.3136176.40351.0078196.24541.0281317.0987-1.1638347.7312-1.9822359.704-2.06539.7322-1.2779180.00021.0066196.67291.0292320.2678-1.2779348.4539-1.9916360-2.0651 （4）总作用力的计算 （MPa）fyZfyfyZfyfyZfyfyZfyfyZfyfyZfy0-1.865139.7322-1.0779180.000211.2681196.672915.2903320.2678NaN348.454-1.79161.0188-1.864543.3288-0.9417180.427711.2764199.84213.405320.9905-0.6372348.75-1.79532.0375-1.862846.9254-0.7997180.855211.3011203.011111.7135321.7133-0.6814349.046-1.79893.0563-1.859950.522-0.6533181.282711.3423206.180210.2406322.436-0.7248349.342-1.80244.0751-1.855954.1186-0.5035181.710211.3996209.34938.9818323.1587-0.7676349.638-1.80585.0939-1.850757.7153-0.3517182.137711.4729212.51847.9174323.8814-0.8098349.934-1.80916.1126-1.844461.3119-0.1988182.565211.5619215.68757.022324.6041-0.8513350.23-1.81237.1314-1.836964.9085-0.0461182.992711.666218.85666.2694325.3269-0.8921350.526-1.81558.1502-1.828368.50510.1055183.420211.7849222.02575.6357326.0496-0.9322350.822-1.81859.169-1.818672.10170.2551183.847711.9179225.19485.0997326.7723-0.9716351.118-1.821410.1877-1.807875.69830.4019184.275212.0644228.36394.6435327.495-1.0104351.415-1.824311.2065-1.795879.29490.5455184.702712.2236231.5334.2522328.2178-1.0484351.711-1.82712.2253-1.782882.89160.6852185.1302