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3 System Design of Lunar Lander
about 0.01 Pa, the axial velocity was more than 3000 m/s, and the Mach number was
over 15.
When lunar lander was approaching lunar surface, the most important effects
are thermal effects of engine plume and its reflux. Analysis shows that the heat
flux increase dramatically on the landing cushion mechanism and bottom plate on
the bottom of lunar lander when the height was decreasing. The maximum heat
flux density was about 400 kW/m
2 on the landing cushion mechanism, as well as
80 kW/m
2 on the bottom plate. But the time was short. It was only 1 to 2 s. The total
heat energy should be evaluated to determine the appropriate thermal protection
materials.
2) Analysis of lunar dust effects
(1) Lunar dust activated by engine plume. The physical simulation model of engine
plume and lunar dust on smooth lunar surface was established by actual thrust
output during soft landing, variation of velocity and attitude for lunar lander.
The interaction between engine plume and lunar dust during soft landing was
digitally simulated for two phases coupled with gas phase (engine jet stream)
and solid phase (lunar dust particles). The example of analysis results is given
as following for the CE-3 lunar lander.
➀ When the height of lunar lander to lunar surface was higher than 20 m,
the effects of engine plume on lunar surface was small and no lunar dust
would be activated.
➁ When the height of lunar lander to lunar surface was lower than 20 m, the
effects of engine plume on lunar dust increase along with decreasing of
the height, as following.
a. Along with decreasing of the height of lunar lander, the pattern of
stream line of the engine plume on lunar surface would change from
spreading along lunar surface to upturning. The upturning angle was
bigger when the height was lower.
b. Along with variation of the height of lunar lander and the stream line
of engine jet stream, lunar dust particles carried by jet stream would
cause growth of particle density on landing site. But the height of
lunar dust particles was obviously lower than the jet stream gas. Even
at the 1 m height to lunar surface, there was no continuous big lunar
dust particle on the surface of lunar lander.
c. If the engine was always ignited during soft landing, there would be
hardly any lunar dust particle under lunar lander and on all surface
of lunar lander because of the filling effect of jet stream gas.
d. If the engine was powered off at 3 m height and lunar lander freely
falls on lunar surface, small lunar dust particles under lunar lander
would move upward along the inertial movement in V shape while
the upward angle was about 20°. There would be small lunar dust
particles stream on the bottom surface and no small particles reflux
on top surface of lunar lander when it was free falling. The effect
3 System Design of Lunar Lander
about 0.01 Pa, the axial velocity was more than 3000 m/s, and the Mach number was
over 15.
When lunar lander was approaching lunar surface, the most important effects
are thermal effects of engine plume and its reflux. Analysis shows that the heat
flux increase dramatically on the landing cushion mechanism and bottom plate on
the bottom of lunar lander when the height was decreasing. The maximum heat
flux density was about 400 kW/m
2 on the landing cushion mechanism, as well as
80 kW/m
2 on the bottom plate. But the time was short. It was only 1 to 2 s. The total
heat energy should be evaluated to determine the appropriate thermal protection
materials.
2) Analysis of lunar dust effects
(1) Lunar dust activated by engine plume. The physical simulation model of engine
plume and lunar dust on smooth lunar surface was established by actual thrust
output during soft landing, variation of velocity and attitude for lunar lander.
The interaction between engine plume and lunar dust during soft landing was
digitally simulated for two phases coupled with gas phase (engine jet stream)
and solid phase (lunar dust particles). The example of analysis results is given
as following for the CE-3 lunar lander.
➀ When the height of lunar lander to lunar surface was higher than 20 m,
the effects of engine plume on lunar surface was small and no lunar dust
would be activated.
➁ When the height of lunar lander to lunar surface was lower than 20 m, the
effects of engine plume on lunar dust increase along with decreasing of
the height, as following.
a. Along with decreasing of the height of lunar lander, the pattern of
stream line of the engine plume on lunar surface would change from
spreading along lunar surface to upturning. The upturning angle was
bigger when the height was lower.
b. Along with variation of the height of lunar lander and the stream line
of engine jet stream, lunar dust particles carried by jet stream would
cause growth of particle density on landing site. But the height of
lunar dust particles was obviously lower than the jet stream gas. Even
at the 1 m height to lunar surface, there was no continuous big lunar
dust particle on the surface of lunar lander.
c. If the engine was always ignited during soft landing, there would be
hardly any lunar dust particle under lunar lander and on all surface
of lunar lander because of the filling effect of jet stream gas.
d. If the engine was powered off at 3 m height and lunar lander freely
falls on lunar surface, small lunar dust particles under lunar lander
would move upward along the inertial movement in V shape while
the upward angle was about 20°. There would be small lunar dust
particles stream on the bottom surface and no small particles reflux
on top surface of lunar lander when it was free falling. The effect