The above equation is known as the breguet range equation. It shows the influence of aircraft, propulsion system, and structural design parameters Relation of overall efficiency, Isp, and thermal efficiency Suppose A fuel is the heating value( heat of combustion, )of fuel (i. e, the energy per unit of fuel mass), in J/kg. The rate of energy release is in f Ah fuel,so mfg 4n fuel m fuel 8 and Fco_- Thrust power(useful work) overall (overall propulsion system efficiency Ii Ah fuel Ideal available energy Hloverall-Aho'sp andRange L. W overall nthermal'propulsivecombustion The Propulsion Energy Conversion Chain The above concepts can be depicted as parts of the propulsion energy conversion train mentioned in Part 0, which shows the process from chemical energy contained in the fuel to energy useful to the vehicle Chemical Mechanical Useful work. Thrust power Heat work mf△nel 2 combustion thermal +Cerit / co Figure 2A-7: The propulsion energy conversion chain The combustion efficiency is near unity unless conditions are far off design and we can regard the two main drivers as the thermal and propulsive efficiencies. The evolution of the overall efficiency of aircraft engines in terms of these quantities is shown below in Figure 2A-8 The transmission efficiency represents the ratio between compressor and turbine power, which is less than unity due to parasitic frictional effects. As with the combustion efficiency, however, this is very close to one and the horizontal axis can thus be regarded essentially as propulsive efficiency 2A-102A-10 The above equation is known as the Breguet range equation. It shows the influence of aircraft, propulsion system, and structural design parameters. Relation of overall efficiency, Isp , and thermal efficiency Suppose ∆hfuel is the heating value (‘heat of combustion’) of fuel (i.e., the energy per unit of fuel mass), in J/kg. The rate of energy release is m˙ f fuel ∆h , so cI c F g h h Fc h h g sp f fuel fuel f fuel fuel 0 0 0 = = m m ˙ ˙ ∆ ∆ ∆ ∆ and Fc h f fuel overall 0 m˙ ∆ = ( ) = Thrust power usefulwork Ideal available energy η (overall propulsion system efficiency) ηoverall fuel sp g h = c I ∆ 0 and Range = ∆h g L D W W fuel overall i f η ln η ηη η overall thermal propulsive = combustion The Propulsion Energy Conversion Chain The above concepts can be depicted as parts of the propulsion energy conversion train mentioned in Part 0, which shows the process from chemical energy contained in the fuel to energy useful to the vehicle. Figure 2A-7: The propulsion energy conversion chain. The combustion efficiency is near unity unless conditions are far off design and we can regard the two main drivers as the thermal and propulsive1 efficiencies. The evolution of the overall efficiency of aircraft engines in terms of these quantities is shown below in Figure 2A-8. 1 The transmission efficiency represents the ratio between compressor and turbine power, which is less than unity due to parasitic frictional effects. As with the combustion efficiency, however, this is very close to one and the horizontal axis can thus be regarded essentially as propulsive efficiency. Chemical 1 energy m h f fuel ⋅ ∆ Heat Mechanical work Useful work: Thrust power ηcombustion ≅ 1 ηthermal ηpropulsive exit c c = + 2 1 0 / m c c exit • − 2 0 2 2 2