// Requires a timestep to be passed to FGNewEngine::init and currently assumes this timestep does not change.
// Could easily be altered to pass a variable timestep to FGNewEngine::update every step instead if required.
//
+// DCL 27/10/00 - Added first stab at cylinder head temperature model
+// See the comment block in the code for details
+//
+// DCL 02/11/00 - Modified EGT code to reduce values to those more representative of a sensor downstream
+//
//////////////////////////////////////////////////////////////////////
#include <simgear/compiler.h>
// cout << "fuel " << m_dot_fuel;
// cout << " air " << m_dot_air << '\n';
-//**************
+//***********************************************************************
+//Calculate percentage power
+
+ // For a given Manifold Pressure and RPM calculate the % Power
+ // Multiply Manifold Pressure by RPM
+ ManXRPM = Manifold_Pressure * RPM;
+ // cout << ManXRPM;
+ // cout << endl;
+
+/*
+// Phil's %power correlation
+ // Calculate % Power
+ Percentage_Power = (+ 7E-09 * ManXRPM * ManXRPM) + ( + 7E-04 * ManXRPM) - 0.1218;
+ // cout << Percentage_Power << "%" << "\t";
+*/
+
+// DCL %power correlation - basically Phil's correlation modified to give slighty less power at the low end
+// might need some adjustment as the prop model is adjusted
+// My aim is to match the prop model and engine model at the low end to give the manufacturer's recommended idle speed with the throttle closed - 600rpm for the Continental IO520
+ // Calculate % Power
+ Percentage_Power = (+ 6E-09 * ManXRPM * ManXRPM) + ( + 8E-04 * ManXRPM) - 1.8524;
+ // cout << Percentage_Power << "%" << "\t";
+
+
+ // Adjust for Temperature - Temperature above Standard decrease
+ // power % by 7/120 per degree F increase, and incease power for
+ // temps below at the same ratio
+ Percentage_Power = Percentage_Power - (FG_ISA_VAR * 7 /120);
+ // cout << Percentage_Power << "%" << "\t";
+
+//******DCL - this bit will need altering or removing if I go to true altitude adjusted manifold pressure
+ // Adjust for Altitude. In this version a linear variation is
+ // used. Decrease 1% for each 1000' increase in Altitde
+ Percentage_Power = Percentage_Power + (FG_Pressure_Ht * 12/10000);
+ // cout << Percentage_Power << "%" << "\t";
+
+
+ //DCL - now adjust power to compensate for mixture
+ //uses a curve fit to the data in the IO360 / O360 operating manual
+ //due to the shape of the curve I had to use a 6th order fit - I am sure it must be possible to reduce this in future,
+ //possibly by using separate fits for rich and lean of best power mixture
+ //first adjust actual mixture to abstract mixture - this is a temporary hack in order to account for the fact that the data I have
+ //dosn't specify actual mixtures and I want to be able to change what I think they are without redoing the curve fit each time.
+ //y=10x-12 for now
+ abstract_mixture = 10.0 * equivalence_ratio - 12.0;
+ float m = abstract_mixture; //to simplify writing the next equation
+ Percentage_of_best_power_mixture_power = ((-0.0012*m*m*m*m*m*m) + (0.021*m*m*m*m*m) + (-0.1425*m*m*m*m) + (0.4395*m*m*m) + (-0.8909*m*m) + (-0.5155*m) + 100.03);
+ Percentage_Power = Percentage_Power * Percentage_of_best_power_mixture_power / 100.0;
+
+ //cout << " %POWER = " << Percentage_Power << '\n';
+
+//***DCL - FIXME - this needs altering - for instance going richer than full power mixture decreases the %power but increases the fuel flow
+ // Now Calculate Fuel Flow based on % Power Best Power Mixture
+ Fuel_Flow = Percentage_Power * Max_Fuel_Flow / 100.0;
+ // cout << Fuel_Flow << " lbs/hr"<< endl;
+
+ // Now Derate engine for the effects of Bad/Switched off magnetos
+ if (Magneto_Left == 0 && Magneto_Right == 0) {
+ // cout << "Both OFF\n";
+ Percentage_Power = 0;
+ } else if (Magneto_Left && Magneto_Right) {
+ // cout << "Both On ";
+ } else if (Magneto_Left == 0 || Magneto_Right== 0) {
+ // cout << "1 Magneto Failed ";
+
+ Percentage_Power = Percentage_Power *
+ ((100.0 - Mag_Derate_Percent)/100.0);
+ // cout << FGEng1_Percentage_Power << "%" << "\t";
+ }
+
+
+
+//**********************************************************************
+//Calculate Exhaust gas temperature
// cout << "Thi = " << equivalence_ratio << '\n';
EGT = T_amb + delta_T_exhaust;
- // cout << " EGT = " << EGT << '\n';
+ //The above gives the exhaust temperature immediately prior to leaving the combustion chamber
+ //Now derate to give a more realistic figure as measured downstream
+ //For now we will aim for a peak of around 400 degC (750 degF)
+
+ EGT *= 0.444 + ((0.544 - 0.444) * Percentage_Power / 100.0);
+
+ EGT_degF = (EGT * 1.8) - 459.67;
+
+ //cout << " EGT = " << EGT << " degK " << EGT_degF << " degF";// << '\n';
//***************************************************************************************
// Calculate Cylinder Head Temperature
CHT_degF = (CHT * 1.8) - 459.67;
- // cout << "CHT = " << CHT_degF << " degF\n";
+ //cout << " CHT = " << CHT_degF << " degF\n";
// End calculate Cylinder Head Temperature
// Engine Power & Torque Calculations
- // For a given Manifold Pressure and RPM calculate the % Power
- // Multiply Manifold Pressure by RPM
- ManXRPM = Manifold_Pressure * RPM;
- // cout << ManXRPM;
- // cout << endl;
-
-/*
-// Phil's %power correlation
- // Calculate % Power
- Percentage_Power = (+ 7E-09 * ManXRPM * ManXRPM) + ( + 7E-04 * ManXRPM) - 0.1218;
- // cout << Percentage_Power << "%" << "\t";
-*/
-// DCL %power correlation - basically Phil's correlation modified to give slighty less power at the low end
-// might need some adjustment as the prop model is adjusted
-// My aim is to match the prop model and engine model at the low end to give the manufacturer's recommended idle speed with the throttle closed - 600rpm for the Continental IO520
- // Calculate % Power
- Percentage_Power = (+ 6E-09 * ManXRPM * ManXRPM) + ( + 8E-04 * ManXRPM) - 1.8524;
- // cout << Percentage_Power << "%" << "\t";
-
-
- // Adjust for Temperature - Temperature above Standard decrease
- // power % by 7/120 per degree F increase, and incease power for
- // temps below at the same ratio
- Percentage_Power = Percentage_Power - (FG_ISA_VAR * 7 /120);
- // cout << Percentage_Power << "%" << "\t";
-
- // Adjust for Altitude. In this version a linear variation is
- // used. Decrease 1% for each 1000' increase in Altitde
- Percentage_Power = Percentage_Power + (FG_Pressure_Ht * 12/10000);
- // cout << Percentage_Power << "%" << "\t";
-
-
- //DCL - now adjust power to compensate for mixture
- //uses a curve fit to the data in the IO360 / O360 operating manual
- //due to the shape of the curve I had to use a 6th order fit - I am sure it must be possible to reduce this in future,
- //possibly by using separate fits for rich and lean of best power mixture
- //first adjust actual mixture to abstract mixture - this is a temporary hack in order to account for the fact that the data I have
- //dosn't specify actual mixtures and I want to be able to change what I think they are without redoing the curve fit each time.
- //y=10x-12 for now
- abstract_mixture = 10.0 * equivalence_ratio - 12.0;
- float m = abstract_mixture; //to simplify writing the next equation
- Percentage_of_best_power_mixture_power = ((-0.0012*m*m*m*m*m*m) + (0.021*m*m*m*m*m) + (-0.1425*m*m*m*m) + (0.4395*m*m*m) + (-0.8909*m*m) + (-0.5155*m) + 100.03);
- Percentage_Power = Percentage_Power * Percentage_of_best_power_mixture_power / 100.0;
-
-
- // Now Calculate Fuel Flow based on % Power Best Power Mixture
- Fuel_Flow = Percentage_Power * Max_Fuel_Flow / 100.0;
- // cout << Fuel_Flow << " lbs/hr"<< endl;
-
- // Now Derate engine for the effects of Bad/Switched off magnetos
- if (Magneto_Left == 0 && Magneto_Right == 0) {
- // cout << "Both OFF\n";
- Percentage_Power = 0;
- } else if (Magneto_Left && Magneto_Right) {
- // cout << "Both On ";
- } else if (Magneto_Left == 0 || Magneto_Right== 0) {
- // cout << "1 Magneto Failed ";
-
- Percentage_Power = Percentage_Power *
- ((100.0 - Mag_Derate_Percent)/100.0);
- // cout << FGEng1_Percentage_Power << "%" << "\t";
- }
// Calculate Engine Horsepower
projects / flightgear.git / commitdiff