diff --git a/engine/include/engine/engine.h b/engine/include/engine/engine.h
index d1d5efc69a57d44c38f791264372f58b69582e31..5a1160a20711f7958b631e7267cd006c3197af89 100644
--- a/engine/include/engine/engine.h
+++ b/engine/include/engine/engine.h
@@ -271,21 +271,30 @@ public:
*/
[[nodiscard]] auto get_thrust_aircraft() -> double;
- /**
+ /**
* @brief Get the scaled engine thrust at the current operating point for the engine
* @return double [N] The thrust of the engine.
*/
[[nodiscard]] auto get_thrust() -> double;
+ /**
+ * @brief Get the TSFC at the current operating point for the engine
+ * @return double [kg/(Ns)] The TSFC of the engine.
+ */
[[nodiscard]] auto get_tsfc() -> double;
+ /**
+ * @brief Get the TSFC including penalties at the current operating point for the engine
+ * @return double [kg/(Ns)] The TSFC of the engine.
+ */
[[nodiscard]] auto get_tsfc_penalties(double delta_isa_T, double shaft_offtake, double bleed_offtake) -> double;
- [[nodiscard]] auto get_tsfc_penalties(double delta_isa_T, double shaft_offtake) -> double;
-
+ /**
+ * @brief Get the thrust at the current operating point for the engine. The thrust setting is interpolated linearly.
+ * @return double [N] The thrust of the engine.
+ */
[[nodiscard]] auto get_thrust_with_lever_position(double lever_position_percent, double mach, double altitude) -> double;
-
/**
* @brief Get the scaled fuel flow at the current operating point
* @return fuelDeck.getVal fuel flow [kg/s] depending on the variables above
@@ -474,9 +483,8 @@ private:
void set_upper_N1_limit();
void set_upper_N1_limit_temperature(const std::string &thrust_rating);
void set_upper_N1_limit_with_overall_fuelflow_pressure_ratio(const std::string &thrust_rating);
- void set_upper_N1_limit_high_pressure_spool_speed(const std::string &thrust_rating);
- void set_upper_N1_limit_power(const std::string &thrust_rating);
void set_N1_to_rating(const std::string &thrust_rating, const double &derate);
+ void calculate_offtake_correction2(const atmosphere& atm, const double& bleedAir, const double& shaftPower, double altitude, double mach);
void calculate_offtake_correction(const atmosphere &atm,
const double &bleed_air_offtake,
const double &shaft_power_offtake);
diff --git a/engine/src/engine.cpp b/engine/src/engine.cpp
index 1b84a52600b74a3de0f716a7c15cb3c2162d7bf0..074f93a25a6ed99bb7ee00749fa99b5d858f2d07 100644
--- a/engine/src/engine.cpp
+++ b/engine/src/engine.cpp
@@ -132,7 +132,7 @@ double Engine::get_thrust_lapse(const std::string &thrust_rating, const atmosphe
0);
double operating_thrust = get_thrust();
// Output is the ratio of the thrusts
- return operating_thrust/base_thrust;
+ return operating_thrust / base_thrust;
}
auto Engine::get_operating_point() -> OperatingPoint
@@ -215,7 +215,6 @@ void Engine::calculate_N1_with_penalties(const double& flight_level,
errMsg << "Could not find low pressure shaft speed N1 for current rating: ";
errMsg << thrust_rating << std::endl;
errMsg << "N1(current): " << this->op_.N << "; ";
- errMsg << "N1(last): " << currentNmom << "; ";
errMsg << "N1(upperLimit): " << this->N_upper_limit_;
throwError(__FILE__, __func__, __LINE__, errMsg.str());
} else {
@@ -565,9 +564,8 @@ auto Engine::get_scaled_SLST() -> double
void Engine::set_lower_N1_limit() {
// Estimation of ground/flight idle
- // FADEC sets minimum fuel flow to prevent flame-out (WF/P3)
// Set lower N1 limit to minimum required fuel
- // (first converged N1 in fuel flow deck for current altitude and Mach number)
+ // first converged N1 in fuel flow deck for current altitude and Mach number
this->N_lower_limit_ = op_.N = engine_data_.get_lower_operating_point(fuelflow).N;
// N_lower_limit_ is increased from min value in deck that shows all valid operating points to first valid value
while (engine_data_.get_deck_value(fuelflow, this->op_) < 0)
@@ -580,27 +578,41 @@ void Engine::set_lower_N1_limit() {
op_.N += N1_step_;
this->N_lower_limit_ = op_.N; // update the N_lower_limit_ variable
}
- // Initialize check variables
- // Check flameout limit deck (WFqP3) if flameout danger is true
- // and ratio of fuelflow to combustion chamber inlet is below limit.
- // In this case N1 is increased
}
void Engine::set_upper_N1_limit() {
// Estimation of upper N1 value
- // FADEC sets maximum fuel flow to prevent over temperatures as a limit of temperatures, pressures, HP spool speed
- // Set upper N1 limit to maximum required fuel
- // (last converged N1 in fuel flow deck for current altitude and Mach number)
+ // last converged N1 in fuel flow deck for current altitude and Mach number
this->N_upper_limit_ = op_.N = engine_data_.get_upper_operating_point(fuelflow).N; // Reset upper N1 limit
// N_upper_limit_ is decreased from max value in valid operating point deck to first valid value
while (engine_data_.get_deck_value(fuelflow, this->op_) < 0)
{
this->op_.N -= N1_step_;
- this->N_upper_limit_ = this->op_.N; // update the N_upper_limit_ variable
+ this->N_upper_limit_ = this->op_.N; // update the N_upper_limit_ variable
+ }
+ while (engine_data_.get_deck_value(thrustdeck, this->op_) < 0)
+ {
+ op_.N -= N1_step_;
+ this->N_lower_limit_ = op_.N; // update the N_lower_limit_ variable
}
}
+void Engine::calculate_offtake_correction2(const atmosphere& atm, const double& bleedAir, const double& shaftPower, double altitude, double mach) {
+ // New calculation approach for the bleed and shaft offtakes of the engine
+ double k_p_power_offtake = 0.0057 + (4.6e-8 * altitude) - (0.0106 * mach)
+ - (4.44e-13 * pow(altitude,2))
+ + (1.85e-7 * altitude * mach)
+ + (0.0049 * pow(mach,2));
+ double delta_sfc_power = this->get_tsfc() * k_p_power_offtake * shaftPower; // Scholz "FUEL CONSUMPTION DUE TO SHAFT POWER OFF-TAKES FROM THE ENGINE"
+ double coreMassFlow{engine_data_.get_deck_value(core_mass_flow, this->op_) * scale_factor_};
+ double overall_mass_flow_{engine_data_.get_deck_value(overall_mass_flow, this->op_) * scale_factor_ / this->W_correction_};
+
+ double thrust_correction_bleed_ = 1. - (2. * ( bleedAir / overall_mass_flow_)); // Ray p. 488
+
+}
+
void Engine::calculate_offtake_correction(const atmosphere& atm, const double& bleedAir, const double& shaftPower) {
+
// The factors for correction were done according to the CF6 installation manual.
// Range of values: Mach: 0-0.95; Relative corrected thirst: 0.2-1
// create temporary operating point to feed into the function
@@ -630,7 +642,7 @@ void Engine::calculate_offtake_correction(const atmosphere& atm, const double& b
N_shaft_offtake_bleed_correction_ = 1.0 -
correctionNBleed(this->op_.Mach, relCorrectedThrust) * relBleed -
correctionNPshaft(this->op_.Mach, relCorrectedThrust) * relCorrectedShaftPower;
- N_shaft_offtake_bleed_correction_ = std::max(1.0, N_shaft_offtake_bleed_correction_); // TODO(Tobi): Do we still need htis comment? // Fix to not let it crash when only shaft power is extruded - minimum value possible was 0.9985
+ N_shaft_offtake_bleed_correction_ = std::max(1.0, N_shaft_offtake_bleed_correction_);
W_fuel_shaft_offtake_bleed_correction_ = 1.0 -
correctionFuelBleed(this->op_.Mach, relCorrectedThrust) * relBleed -
@@ -647,35 +659,10 @@ void Engine::set_N1_to_rating(const std::string& thrustRating, const double& der
errorMessage << "Invalid range!" << std::endl;
errorMessage << "Derate factor ";
errorMessage << derate << " (0.1 < X < 1.0 is allowed)" << std::endl;
- errorMessage << "Abort program!" << std::endl;
throwError(__FILE__, __func__, __LINE__, errorMessage.str());
}
- if (thrustRating == "takeoff" || thrustRating == "maximum_continuous") {
+ if (thrustRating == "takeoff" || thrustRating == "maximum_continuous" || thrustRating == "climb" || thrustRating == "cruise") {
this->op_.N = std::max(this->N_upper_limit_ * derate, this->N_lower_limit_);
- // std::stringstream errMsg; // TODO(Oli): this should be a INFO
- // errMsg << "N_mom (TO/MaxCont): " << this->op_.N << std::endl;
- // throwError(__FILE__, __func__, __LINE__, errMsg.str());
- if (this->op_.N > this->N_upper_limit_ * derate) {
- this->is_derate_increased_ = true;
- }
- } else if (thrustRating == "climb") {
- this->op_.N = std::max(this->N_upper_limit_ * derate,
- this->N_lower_limit_);
- // std::stringstream errMsg; // TODO(Oli): this should be a INFO
- // errMsg << "N_mom (Climb): " << this->op_.N << std::endl;
- // throwError(__FILE__, __func__, __LINE__, errMsg.str());
- if (this->op_.N > this->N_upper_limit_ * derate) {
- this->is_derate_increased_ = true;
- }
- } else if (thrustRating == "cruise") {
- this->op_.N = std::max(this->N_upper_limit_* derate,
- this->N_lower_limit_);
- // std::stringstream errMsg; // TODO(Oli): this should be a INFO
- // errMsg << "N_mom (Cruise): " << this->op_.N << std::endl;
- // throwError(__FILE__, __func__, __LINE__, errMsg.str());
- if (this->op_.N > this->N_upper_limit_ * derate) {
- this->is_derate_increased_ = true;
- }
} else if (thrustRating == "idle") {
this->op_.N = this->N_lower_limit_;
// std::stringstream errMsg; // TODO(Oli): this should be a INFO
@@ -709,12 +696,6 @@ void Engine::set_upper_N1_limit_with_overall_fuelflow_pressure_ratio(const std::
// N_upper_limit_ is decreased from max value in fuel deck to first valid value
}
-void Engine::set_upper_N1_limit_high_pressure_spool_speed(const std::string &thrust_rating) {
-}
-
-void Engine::set_upper_N1_limit_power(const std::string &thrust_rating) {
-}
-
double Engine::calculate_polynom(const double coeffs[], const double x, const double y) {
// Calculate the polynomial value using a bi-quadratic symmetric approach
const double correction_factor =