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Many engine model tweaks, updates, and enhancements.

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curt 2001-10-05 20:27:01 +00:00
parent cb0aa1baa1
commit 07f5955f8c
2 changed files with 523 additions and 639 deletions
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src/FDM/IO360.cxx
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src/FDM/IO360.hxx
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@ -1,10 +1,9 @@
// Module: 10520c.c
// Author: Phil Schubert
// Date started: 12/03/99
// Purpose: Models a Continental IO-520-M Engine
// Called by: FGSimExec
//
// Copyright (C) 1999 Philip L. Schubert (philings@ozemail.com.au)
// IO360.hxx - a piston engine model currently for the IO360 engine fitted to the C172
// but with the potential to model other naturally aspirated piston engines
// given appropriate config input.
//
// Written by David Luff, started 2000.
// Based on code by Phil Schubert, started 1999.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
@ -18,34 +17,8 @@
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
//
// Further information about the GNU General Public License can also
// be found on the world wide web at http://www.gnu.org.
//
// FUNCTIONAL DESCRIPTION
// ------------------------------------------------------------------------
// Models a Continental IO-520-M engine. This engine is used in Cessna
// 210, 310, Beechcraft Bonaza and Baron C55. The equations used below
// were determined by a first and second order curve fits using Excel.
// The data is from the Cessna Aircraft Corporations Engine and Flight
// Computer for C310. Part Number D3500-13
//
// ARGUMENTS
// ------------------------------------------------------------------------
//
//
// HISTORY
// ------------------------------------------------------------------------
// 12/03/99 PLS Created
// 07/03/99 PLS Added Calculation of Density, and Prop_Torque
// 07/03/99 PLS Restructered Variables to allow easier implementation
// of Classes
// 15/03/99 PLS Added Oil Pressure, Oil Temperature and CH Temp
// ------------------------------------------------------------------------
// INCLUDES
// ------------------------------------------------------------------------
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#ifndef _IO360_HXX_
#define _IO360_HXX_
@ -65,109 +38,107 @@ class FGNewEngine {
private:
float CONVERT_HP_TO_WATTS;
// These constants should probably be moved eventually
float CONVERT_CUBIC_INCHES_TO_METERS_CUBED;
float CONVERT_HP_TO_WATTS;
// Control and environment inputs
// Properties of working fluids
float Cp_air; // J/KgK
float Cp_fuel; // J/KgK
float calorific_value_fuel; // W/Kg
float rho_fuel; // kg/m^3
float rho_air; // kg/m^3
// environment inputs
float p_amb_sea_level; // Sea level ambient pressure in Pascals
float p_amb; // Ambient pressure at current altitude in Pascals
float T_amb; // ditto deg Kelvin
// Control inputs
float Throttle_Lever_Pos; // 0 = Closed, 100 = Fully Open
float Propeller_Lever_Pos; // 0 = Full Course 100 = Full Fine
float Mixture_Lever_Pos; // 0 = Idle Cut Off 100 = Full Rich
//misc
float IAS;
// 0 = Closed, 100 = Fully Open
float Throttle_Lever_Pos;
// 0 = Full Course 100 = Full Fine
float Propeller_Lever_Pos;
// 0 = Idle Cut Off 100 = Full Rich
float Mixture_Lever_Pos;
double time_step;
// Engine Specific Variables used by this program that have limits.
// Will be set in a parameter file to be read in to create
// and instance for each engine.
float Max_Manifold_Pressure; //will be lower than ambient pressure for a non turbo/super charged engine due to losses through the throttle. This is the sea level full throttle value.
float Min_Manifold_Pressure; //Closed throttle valueat idle - governed by the idle bypass valve
float Max_RPM;
float Min_RPM;
float Max_Fuel_Flow;
float Mag_Derate_Percent;
float MaxHP;
float Gear_Ratio;
// Engine Specific Variables that should be read in from a config file
float MaxHP; // Horsepower
float displacement; // Cubic inches
float displacement_SI; //m^3 (derived from above rather than read in)
float engine_inertia; //kg.m^2
float prop_inertia; //kg.m^2
float Max_Fuel_Flow; // Units??? Do we need this variable any more??
// Initialise Engine Variables used by this instance
// Engine specific variables that maybe should be read in from config but are pretty generic and won't vary much for a naturally aspirated piston engine.
float Max_Manifold_Pressure; // inches Hg - typical manifold pressure at full throttle and typical max rpm
float Min_Manifold_Pressure; // inches Hg - typical manifold pressure at idle (closed throttle)
float Max_RPM; // rpm - this is really a bit of a hack and could be make redundant if the prop model works properly and takes tips at speed of sound into account.
float Min_RPM; // rpm - possibly redundant ???
float Mag_Derate_Percent; // Percentage reduction in power when mags are switched from 'both' to either 'L' or 'R'
float Gear_Ratio; // Gearing between engine and propellor
float n_R; // Number of cycles per power stroke - 2 for a 4 stroke engine.
// Engine Variables not read in from config file
float RPM; // rpm
float Percentage_Power; // Power output as percentage of maximum power output
float Manifold_Pressure; // Inches
float RPM;
float Fuel_Flow_gals_hr; // gals/hour
float Torque;
float CHT; // Cylinder head temperature deg K
float Manifold_Pressure; // Inches Hg
float Fuel_Flow_gals_hr; // USgals/hour
float Torque_lbft; // lb-ft
float Torque_SI; // Nm
float CHT_degK; // Cylinder head temperature deg K
float CHT_degF; // Ditto in deg Fahrenheit
float EGT; // Exhaust gas temperature deg K
float EGT_degF; // Exhaust gas temperature deg Fahrenheit
float Mixture;
float Oil_Pressure; // PSI
float Oil_Temp; // Deg C
float current_oil_temp; // deg K
/**** one of these is superfluous !!!!***/
float HP; // Current power output in HP
float Power_SI; // Current power output in Watts
float Torque_SI; // Torque in Nm
float Torque_FMEP; // The component of Engine torque due to FMEP (Nm)
float RPS;
float Torque_Imbalance;
bool running; //flag to indicate the engine is running self sustaining
bool cranking; //flag to indicate the engine is being cranked
bool spark; //flag to indicate a spark is available
bool fuel; //flag to indicate fuel is available
//DCL
float angular_velocity_SI; // rad/s
float Torque_FMEP; // The component of Engine torque due to FMEP (Nm)
float Torque_Imbalance; // difference between engine and prop torque
float EGT; // Exhaust gas temperature deg K
float EGT_degF; // Exhaust gas temperature deg Fahrenheit
float volumetric_efficiency;
float combustion_efficiency;
float equivalence_ratio;
float v_dot_air;
float m_dot_air;
float m_dot_fuel;
float swept_volume;
float True_Manifold_Pressure; //in Hg
float rho_air_manifold;
float R_air;
float p_amb_sea_level; // Pascals
float p_amb; // Pascals
float T_amb; // deg Kelvin
float calorific_value_fuel;
float rho_air;
float rho_fuel; // kg/m^3
float thi_sea_level;
float delta_T_exhaust;
float displacement; // Engine displacement in cubic inches - to be read in from config file for each engine
float displacement_SI; // ditto in meters cubed
float Cp_air; // J/KgK
float Cp_fuel; // J/KgK
float heat_capacity_exhaust;
float enthalpy_exhaust;
float Percentage_of_best_power_mixture_power;
float equivalence_ratio; // ratio of stoichiometric AFR over actual AFR
float thi_sea_level; // the equivalence ratio we would be running at assuming sea level air denisity in the manifold
float v_dot_air; // volume flow rate of air into engine - m^3/s
float m_dot_air; // mass flow rate of air into engine - kg/s
float m_dot_fuel; // mass flow rate of fuel into engine - kg/s
float swept_volume; // total engine swept volume - m^3
/********* swept volume or the geometry used to calculate it should be in the config read section surely ??? ******/
float True_Manifold_Pressure; //in Hg - actual manifold gauge pressure
float rho_air_manifold; // denisty of air in the manifold - kg/m^3
float R_air; // Gas constant of air (287) UNITS???
float delta_T_exhaust; // Temperature change of exhaust this time step - degK
float heat_capacity_exhaust; // exhaust gas specific heat capacity - J/kgK
float enthalpy_exhaust; // Enthalpy at current exhaust gas conditions - UNITS???
float Percentage_of_best_power_mixture_power; // Current power as a percentage of what power we would have at the same conditions but at best power mixture
float abstract_mixture; //temporary hack
float engine_inertia; //kg.m^2
float prop_inertia; //kg.m^2
float angular_acceleration; //rad/s^2
float n_R; //Number of cycles per power stroke
float FMEP; //Friction Mean Effective Pressure (Pa)
double time_step;
// Various bits of housekeeping describing the engines state.
bool running; // flag to indicate the engine is running self sustaining
bool cranking; // flag to indicate the engine is being cranked
int crank_counter; // Number of iterations that the engine has been cranked non-stop
bool spark; // flag to indicate a spark is available
bool fuel; // flag to indicate fuel is available
// Propellor Variables
float FGProp1_Thrust;
float FGProp1_RPS;
float FGProp1_Blade_Angle;
float FGProp1_RPS; // rps
float prop_torque; // Nm
float prop_thrust; // Newtons
float blade_length; // meters
float forward_velocity; // m/s
float angular_velocity_SI; // rad/s
float prop_power_consumed_SI; // Watts
float prop_power_consumed_HP; // HP
double prop_diameter; // meters
double J; // advance ratio - dimensionless
double Cp_20; // coefficient of power for 20 degree blade angle
double Cp_25; // coefficient of power for 25 degree blade angle
double Cp; // Our actual coefficient of power
double blade_angle; // degrees
double neta_prop_20;
double neta_prop_25;
double neta_prop; // prop efficiency
double prop_diameter; // meters
double blade_angle; // degrees
// MEMBER FUNCTIONS
// Calculate Engine RPM based on Propellor Lever Position
float Calc_Engine_RPM(float Position);
@ -181,18 +152,32 @@ private:
// Calculate percentage of best power mixture power based on equivalence ratio
float Power_Mixture_Correlation(float thi_actual);
// Calculate exhaust gas temperature rise
// Calculate exhaust gas temperature change
float Calculate_Delta_T_Exhaust(void);
// Calculate cylinder head temperature
float FGNewEngine::Calc_CHT(float CHT);
void FGNewEngine::Calc_EGT(void);
// Calculate fuel flow in gals/hr
void FGNewEngine::Calc_Fuel_Flow_Gals_Hr(void);
// Calculate current percentage power
void FGNewEngine::Calc_Percentage_Power(bool mag_left, bool mag_right);
// Calculate Oil Temperature
float Calc_Oil_Temp (float Fuel_Flow, float Mixture, float IAS);
float Calc_Oil_Temp (float oil_temp);
// Calculate Oil Pressure
float Calc_Oil_Press (float Oil_Temp, float Engine_RPM);
// Propeller calculations.
void FGNewEngine::Do_Prop_Calcs(void);
public:
ofstream outfile;
// ofstream outfile;
//constructor
FGNewEngine() {
@ -234,9 +219,6 @@ public:
// accessors
inline float get_RPM() const { return RPM; }
inline float get_Manifold_Pressure() const { return True_Manifold_Pressure; }
inline float get_FGProp1_Thrust() const { return FGProp1_Thrust; }
inline float get_FGProp1_Blade_Angle() const { return FGProp1_Blade_Angle; }
// inline float get_Rho() const { return Rho; }
inline float get_MaxHP() const { return MaxHP; }
inline float get_Percentage_Power() const { return Percentage_Power; }
@ -245,6 +227,7 @@ public:
inline float get_prop_thrust_SI() const { return prop_thrust; }
inline float get_prop_thrust_lbs() const { return (prop_thrust * 0.2248); }
inline float get_fuel_flow_gals_hr() const { return (Fuel_Flow_gals_hr); }
inline float get_oil_temp() const { return ((current_oil_temp * 1.8) - 459.67); }
};