放热率计算.docx

VB计算发动机放热率半球形燃烧室的482Q汽油机缸径为82mm，行程为86mm，压缩比为8.2，进气门迟闭角为10CA；排气门提前角为9.5CA。当转速为3200r/mi，油门开度为92%，充气效率为0.74，空燃比为15.3，点火提前角为20CA，平均有效压力为7.92bar，有效功率为38.4kW，比油耗为282g/kW.h时，根据不同曲轴转角下已知的气缸压力，本文通过VB编程语言计算出：1.缸内温度随曲轴转角的变化规律，缸内最高温度及其对应的曲轴转角；2.缸内压力升高率随曲轴转角的变化规律；最大压力升高率及其对应的曲轴转角；3.平均指示压力、指示功率、指示热效率、机械效率。以下是部分程序及结果。压力升高率Private Sub Command1_Click()定义常数Dim Ang(1 To 682) As Double 曲轴转角Dim pre(1 To 682) As Double 缸内压力Dim dp(1 To 680) As Double 压力升高率Dim mdp As Single 最大压力升高率Dim mdpang As Single 最大压力升高率对应的曲轴转角载入数据Dim i As DoubleDim ii As DoubleDim j As Doublefileno = FreeFileOpen App.Path & shuju.txt For Input As #filenoi = 1Do While Not EOF(fileno) Input #fileno, Ang(i), pre(i) i = i + 1LoopClose #fileno计算压力升高率For ii = 1 To 680 dp(ii) = (pre(ii + 1) - pre(ii) / 0.5 / 1000Next ii求最大压力升高率及对应的曲轴转角mdp = dp(1)mdpang = Ang(1)For j = 2 To 680 If dp(j) mdp Then mdp = dp(j) mdpang = Ang(j) End IfNext j绘制压力升高率随曲轴转角的变化并显示最大压力升高率及对应的曲轴转角Picture1.ClsPicture1.ScaleMode = 2Picture1.Scale (-200, 0.25)-(200, -0.15) 自定义坐标系Picture1.ForeColor = RGB(255, 255, 0)Picture1.DrawWidth = 3Picture1.Line (0, -140)-(0, 270) 画Y轴Picture1.Line (-200, 0)-(200, 0) 画X 轴Picture1.DrawWidth = 6Picture1.PSet (0, 0), RGB(0, 255, 0) 画原点Picture1.ForeColor = RGB(0, 0, 255)Picture1.CurrentX = 2Picture1.CurrentY = -2Picture1.Print o 标记原点Picture1.ForeColor = RGB(0, 100, 255)Picture1.CurrentX = -50Picture1.CurrentY = -0.13Picture1.Print 压力升高率随曲轴转角的变化关系Picture1.ForeColor = RGB(255, 0, 255)Picture1.CurrentX = 7Picture1.CurrentY = 0.2Picture1.Print 最高压力升高率为 & mdp & MPa/A & 其对应的曲轴转角为 & mdpang & Picture1.DrawWidth = 2Picture1.ForeColor = RGB(255, 0, 0)For k = 1 To 680 Picture1.PSet (Ang(k), dp(k)Next kEnd SubPrivate Sub Command2_Click()Dim a As DoubleDim t(1 To 682) As DoubleDim v(1 To 682) As DoubleDim b As IntegerDim bb As IntegerDim y As IntegerDim mt As DoubleDim mtang As DoubleDim Ang(1 To 682) As Double 曲轴转角Dim pre(1 To 682) As Double 缸内压力fileno = FreeFileOpen App.Path & shuju.txt For Input As #filenoa = 1Do While Not EOF(fileno) Input #fileno, Ang(a), pre(a) a = a + 1LoopClose #filenoFor b = 1 To 682 Ang(b) = Ang(b) / 180 * 3.1415926 v(b) = 227083.7418 * (1.2778 - Cos(Ang(b) + 3.4884 * (1 - Sqr(1 - 0.0822 * Sin(Ang(b) * Sin(Ang(b) / 1000000 t(b) = pre(b) * v(b) / 0.1305Next bmt = t(1)mtang = Ang(1)For bb = 2 To 681 If t(bb) mt Then mt = t(bb) mtang = Ang(bb) End IfNext bbmtang = mtang * 180 / 3.1415926绘制温度随曲轴转角的变化关系图，并显示最高温度及其对应的曲轴转角Picture1.ClsPicture1.ScaleMode = 2Picture1.Scale (-4, 3000)-(4, -200) 自定义坐标系Picture1.ForeColor = RGB(255, 255, 0)Picture1.DrawWidth = 3Picture1.Line (0, -150)-(0, 18100) 画Y轴Picture1.Line (-200, 0)-(200, 0) 画X 轴Picture1.DrawWidth = 6Picture1.PSet (0, 0), RGB(0, 255, 0) 画原点Picture1.ForeColor = RGB(0, 0, 255)Picture1.CurrentX = 0.05Picture1.CurrentY = -2Picture1.Print o 标记原点Picture1.ForeColor = RGB(0, 100, 255)Picture1.CurrentX = -1Picture1.CurrentY = -100Picture1.Print 温度随曲轴转角的变化关系Picture1.ForeColor = RGB(255, 0, 255)Picture1.CurrentX = -4Picture1.CurrentY = 2000Picture1.Print 最高温度为 & mt & k & 其对应的曲轴转角为 & mtang & Picture1.DrawWidth = 3Picture1.ForeColor = RGB(255, 0, 0)For y = 1 To 681 Picture1.PSet (Ang(y), t(y)Next yEnd Sub显示平均指示压力Private Sub Command3_Click()Dim pmi As Doublepmi = w / 0.453937pmi = Round(pmi, 2)Picture1.ClsPicture1.Print 平均指示压力= & pmi & MpaEnd Sub显示指示功率Private Sub Command4_Click()Dim pi As Doublepi = w * 106.67pi = Round(pi, 2)Picture1.ClsPicture1.Print 指示功率= & pi & kwEnd Sub显示热效率Private Sub Command5_Click()Picture1.ClsPicture1.Print 指示热效率=0.29End Sub显示机械效率Private Sub Command6_Click()Dim nm As DoublePicture1.Clsnm = 0.36 / wnm = Round(nm, 2)Picture1.Print 机械效率= & nmEnd Sub计算指示功Private Sub Form_Load()Dim yl(1 To 682) As Double Dim jd(1 To 682) As Double Dim i As Double fileno = FreeFile Open App.Path & shuju.txt For Input As #fileno i = 1 Do While Not EOF(fileno) Input #1, jd(i), yl(i) i = i + 1 Loop Close #1 w = 0 For i = 1 To 682 jd(i) = jd(i) * 3.1416 / 180 w = w + 1.9809 * yl(i) * (Sin(jd(i) + 0.2867 * Sin(jd(i) * Cos(jd(i) / Sqr(1 - Sin