Turbine Engine Design
Overview
Turbine engines provide a tremendous amount of thrust for an aircraft. Takeoff requires the maximum thrust available to accelerate the aircraft from rest to takeoff speed before the end the runway. During cruise the engines must overcome drag throughout the flight. Engine designers must balance the thrust needs with fuel economy. Inefficient engines mean that more fuel must be carried and more fuel is used than needed. Both result in a cost increase for the airline operator or a military.
In this activity I use the NASA software simulator to design a turbine engine
that will be the most fuel-efficient engine.
Turbine engines provide a tremendous amount of thrust for an aircraft. Takeoff requires the maximum thrust available to accelerate the aircraft from rest to takeoff speed before the end the runway. During cruise the engines must overcome drag throughout the flight. Engine designers must balance the thrust needs with fuel economy. Inefficient engines mean that more fuel must be carried and more fuel is used than needed. Both result in a cost increase for the airline operator or a military.
In this activity I use the NASA software simulator to design a turbine engine
that will be the most fuel-efficient engine.
Engine Information- Ramjet
Ramjets cannot produce thrust at zero airspeed; they cannot move an aircraft from a standstill. A ramjet powered vehicle, requires an assisted take off to accelerate it to a speed where it begins to produce thrust.Ramjets work most efficiently at supersonic speeds around Mach 3 (2,284 mph; 3,675 km/h). This type of engine can operate up to speeds of Mach 6 (2,041.7 m/s; 7,350 km/h). Ramjets can be particularly useful in applications requiring a small and simple mechanism for high-speed use, such as missiles or artillery shells. Weapon designers are looking to use ramjet technology in artillery shells to give added range. They have also been used successfully, though not efficiently, as tip jets on the end of helicopter rotors.
Ramjets cannot produce thrust at zero airspeed; they cannot move an aircraft from a standstill. A ramjet powered vehicle, requires an assisted take off to accelerate it to a speed where it begins to produce thrust.Ramjets work most efficiently at supersonic speeds around Mach 3 (2,284 mph; 3,675 km/h). This type of engine can operate up to speeds of Mach 6 (2,041.7 m/s; 7,350 km/h). Ramjets can be particularly useful in applications requiring a small and simple mechanism for high-speed use, such as missiles or artillery shells. Weapon designers are looking to use ramjet technology in artillery shells to give added range. They have also been used successfully, though not efficiently, as tip jets on the end of helicopter rotors.
Inlet
Ramjets try to exploit the very high dynamic pressure within the air approaching the intake lip. An efficient intake will recover much of the freestream stagnation pressure, which is used to support the combustion and expansion process in the nozzle.
Most ramjets operate at supersonic flight speeds and use one or more conical (or oblique) shock waves, terminated by a strong normal shock, to slow down the airflow to a subsonic velocity at the exit of the intake. Further diffusion is then required to get the air velocity down to a suitable level for the combustor.
Subsonic intakes on ramjets are relatively simple.
Subsonic ramjets do not need such a sophisticated inlet since the airflow is already subsonic and a simple hole is usually used. This would also work at slightly supersonic speeds, but as the air will choke at the inlet, this is inefficient.
The inlet is divergent, to provide a constant inlet speed of Mach 0.5 (170.15 m/s; 612.5 km/h).
Combustor
As with other jet engines, the combustor's job is to create hot air, by burning a fuel with the air at essentially constant pressure. The airflow through the jet engine is usually quite high, so sheltered combustion zones are produced by using 'flame holders' to stop the flames from blowing out.
Since there is no downstream turbine, a ramjet combustor can safely operate at stoichiometric fuel:air ratios, which implies a combustor exit stagnation temperature of the order of 2,400 K (2,130 °C; 3,860 °F) for kerosene. Normally, the combustor must be capable of operating over a wide range of throttle settings, for a range of flight speeds/altitudes. Usually, a sheltered pilot region enables combustion to continue when the vehicle intake undergoes high yaw/pitch during turns. Other flame stabilization techniques make use of flame holders, which vary in design from combustor cans to simple flat plates, to shelter the flame and improve fuel mixing. Overfuelling the combustor can cause the normal shock within a supersonic intake system to be pushed forward beyond the intake lip, resulting in a substantial drop in engine airflow and net thrust.
Nozzles
The propelling nozzle is a critical part of a ramjet design, since it accelerates exhaust flow to produce thrust.
For a ramjet operating at a subsonic flight Mach number, exhaust flow is accelerated through a converging nozzle. For a supersonic flight Mach number, acceleration is typically achieved via a convergent-divergent nozzle.
Ramjets try to exploit the very high dynamic pressure within the air approaching the intake lip. An efficient intake will recover much of the freestream stagnation pressure, which is used to support the combustion and expansion process in the nozzle.
Most ramjets operate at supersonic flight speeds and use one or more conical (or oblique) shock waves, terminated by a strong normal shock, to slow down the airflow to a subsonic velocity at the exit of the intake. Further diffusion is then required to get the air velocity down to a suitable level for the combustor.
Subsonic intakes on ramjets are relatively simple.
Subsonic ramjets do not need such a sophisticated inlet since the airflow is already subsonic and a simple hole is usually used. This would also work at slightly supersonic speeds, but as the air will choke at the inlet, this is inefficient.
The inlet is divergent, to provide a constant inlet speed of Mach 0.5 (170.15 m/s; 612.5 km/h).
Combustor
As with other jet engines, the combustor's job is to create hot air, by burning a fuel with the air at essentially constant pressure. The airflow through the jet engine is usually quite high, so sheltered combustion zones are produced by using 'flame holders' to stop the flames from blowing out.
Since there is no downstream turbine, a ramjet combustor can safely operate at stoichiometric fuel:air ratios, which implies a combustor exit stagnation temperature of the order of 2,400 K (2,130 °C; 3,860 °F) for kerosene. Normally, the combustor must be capable of operating over a wide range of throttle settings, for a range of flight speeds/altitudes. Usually, a sheltered pilot region enables combustion to continue when the vehicle intake undergoes high yaw/pitch during turns. Other flame stabilization techniques make use of flame holders, which vary in design from combustor cans to simple flat plates, to shelter the flame and improve fuel mixing. Overfuelling the combustor can cause the normal shock within a supersonic intake system to be pushed forward beyond the intake lip, resulting in a substantial drop in engine airflow and net thrust.
Nozzles
The propelling nozzle is a critical part of a ramjet design, since it accelerates exhaust flow to produce thrust.
For a ramjet operating at a subsonic flight Mach number, exhaust flow is accelerated through a converging nozzle. For a supersonic flight Mach number, acceleration is typically achieved via a convergent-divergent nozzle.
Technical Documentation
Ramjet. (2014, December 7). In Wikipedia, The Free Encyclopedia. Retrieved 13:09, December 8, 2014, from http://en.wikipedia.org/w/index.php?title=Ramjet&oldid=637084848