Calculating the specific impulse for a pulsed detonation engine (PDE) is challenging because PDEs operate on a different principle compared to traditional rocket engines. PDEs use detonation waves to compress and ignite the fuel-air mixture periodically, generating thrust. The intermittent nature of detonation cycles makes it less straightforward to apply the traditional specific impulse formula.
The efficiency and performance of a PDE are typically evaluated based on metrics such as the thrust generated per detonation cycle, the frequency of detonation cycles, and the overall energy conversion efficiency. The traditional specific impulse formula may not provide a meaningful measure of PDE performance due to the intermittent and dynamic nature of detonation waves.
It is defined as the thrust generated per unit of propellant expended and is expressed in seconds.
where,
- is the specific impulse of the rocket engine (in seconds, s)
- F is the Thrust Produced
- ṁ is the mass flow rate of propellant in KG/Sec
- g0 is the acceleration due to gravity