Pulsejets rely on periodic combustion pulses rather than continuous combustion, and their operation is typically more complex.
Pulsejets generate thrust by creating repeating cycles of intake, compression, combustion, and exhaust. The specific impulse of a pulsejet can be influenced by factors such as the frequency and efficiency of the combustion pulses, the combustion characteristics, and the design of the engine.
Due to the unique nature of pulsejet operation, specific impulse may not be as commonly used or directly comparable to other propulsion systems like rockets. The efficiency of a pulsejet is often evaluated based on its thrust-to-drag ratio, fuel efficiency, and other relevant parameters.
The specific impulse formula is generally expressed as:
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