The improvement of the thrust and specific impulse by heating and elongating of de Laval nozzle
- Paper number
IAC-08.C4.3.15
- Author
Mr. Yuuki IWAKI, Hokkaido University, Japan
- Coauthor
Prof. Tsuyoshi Totani, Hokkaido University, Japan
- Coauthor
Prof. Harunori Nagata, Hokkaido University, Japan
- Coauthor
Mr. Tetsushi NAGANUMA, Hokkaido University, Japan
- Year
2008
- Abstract
It is difficult that the propulsion systems using chemical reactions are mounted on the microsatellites launched by piggyback systems. Propulsion systems such as resistojets or gas thrusters have low thrust and low specific impulse because the enthalpy of the propellant is low.
We have regarded of the heating of propellant at de Laval nozzle to increase the enthalpy of propellant. In the case of propulsion systems without chemical reactions, the temperature of propellant becomes lower than the temperature of the wall of the nozzle. The lower the enthalpy of propellant is, the more the heat transfer from the wall of the nozzle is relatively.
The developed analysis program consists of two main parts that calculate the one-dimensional thermal conduction of the wall of the nozzle and one-dimensional steady continuous flow without a chemical reaction of the propellant. The boundary conditions of the former part are the constant temperature at the inlet of the nozzle, the convective heat transfer between the wall and the propellant and the radiative heat transfer between the wall and the surrounding. The boundary conditions in the latter part are the constant temperature and the constant mass flow rate at the inlet of the nozzle, zero of the ambient pressure and the convective heat transfer between the wall and the propellant.
The analysis objects are the nozzle made of aluminum alloy and water as propellant. The diameters of nozzle are 6 mm at the inlet, 1 mm at the throat and 20 mm at the outlet. The lengths between the inlet and the throat and between the throat and the outlet are 9.2 mm and 40 mm, respectively. The radial thickness is 2 mm.
In the case that the mass flow rate is 1 g/min and the temperatures of the wall and the propellant at the inlet of the nozzle are 600 K, the specific impulse improves 20 % against the specific impulse in the nozzle in which the propellant changes adiabatically. The heat input in the nozzle is 26 % compared to the enthalpy of the propellant at the inlet. The mass reduction of the propellant by heating at the nozzle is 2 kg despite 7.3 g of the mass of the nozzle in the case of achieving 1 km/s of the velocity change for 50 kg microsatellite.
The heating and elongating of the nozzle is very effective for the propulsion system such as gas thrusters.
- Abstract document
- Manuscript document
(absent)