330024e0b7
modeling of a simple single vacuum system with a pump source on each engine in a multiengine aircraft. The highest rpm engine takes priority for driving the vacuum system.
111 lines
2.7 KiB
C++
111 lines
2.7 KiB
C++
// vacuum.cxx - a vacuum pump connected to the aircraft engine.
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// Written by David Megginson, started 2002.
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//
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// This file is in the Public Domain and comes with no warranty.
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#include "vacuum.hxx"
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#include <Main/fg_props.hxx>
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VacuumSystem::VacuumSystem ( SGPropertyNode *node )
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:
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name("vacuum"),
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num(0),
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scale(1.0)
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{
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rpms.clear();
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int i;
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for ( i = 0; i < node->nChildren(); ++i ) {
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SGPropertyNode *child = node->getChild(i);
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string cname = child->getName();
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string cval = child->getStringValue();
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if ( cname == "name" ) {
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name = cval;
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} else if ( cname == "number" ) {
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num = child->getIntValue();
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} else if ( cname == "rpm" ) {
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rpms.push_back(cval);
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} else if ( cname == "scale" ) {
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scale = child->getDoubleValue();
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} else {
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SG_LOG( SG_SYSTEMS, SG_WARN, "Error in vacuum config logic" );
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if ( name.length() ) {
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SG_LOG( SG_SYSTEMS, SG_WARN, "Section = " << name );
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}
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}
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}
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}
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VacuumSystem::VacuumSystem( int i )
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{
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name = "vacuum";
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num = i;
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rpms.clear();
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scale = 1.0;
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}
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VacuumSystem::~VacuumSystem ()
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{
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}
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void
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VacuumSystem::init()
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{
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unsigned int i;
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string branch;
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branch = "/systems/" + name;
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SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
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_serviceable_node = node->getChild("serviceable", 0, true);
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for ( i = 0; i < rpms.size(); i++ ) {
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SGPropertyNode_ptr _rpm_node = fgGetNode(rpms[i].c_str(), true);
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_rpm_nodes.push_back( _rpm_node );
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}
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_pressure_node = fgGetNode("/environment/pressure-inhg", true);
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_suction_node = node->getChild("suction-inhg", 0, true);
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}
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void
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VacuumSystem::bind ()
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{
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}
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void
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VacuumSystem::unbind ()
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{
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}
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void
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VacuumSystem::update (double dt)
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{
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// Model taken from steam.cxx
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double suction;
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unsigned int i;
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if (!_serviceable_node->getBoolValue()) {
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suction = 0.0;
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} else {
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// select the source with the max rpm
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double rpm = 0.0;
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for ( i = 0; i < _rpm_nodes.size(); i++ ) {
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double tmp = _rpm_nodes[i]->getDoubleValue() * scale;
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if ( tmp > rpm ) {
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rpm = tmp;
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}
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}
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double pressure = _pressure_node->getDoubleValue();
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// This magic formula yields about 4 inhg at 700 rpm
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suction = pressure * rpm / (rpm + 4875.0);
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// simple regulator model that clamps smoothly to about 5 inhg
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// over a normal rpm range
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double max = (rpm > 0 ? 5.39 - 1.0 / ( rpm * 0.00111 ) : 0);
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if ( suction < 0.0 ) suction = 0.0;
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if ( suction > max ) suction = max;
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}
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_suction_node->setDoubleValue(suction);
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}
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// end of vacuum.cxx
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