8.5 Testing and Verification of Propulsion Subsystem
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strength and stiffness. A great many ground tests should be conducted including
shell load bearing, management device, discharge performance and reliability. For
example, the lightweight composite wrapped aluminum alloy diaphragm tanks fixed
at both ends were applied in propulsion subsystem of the Chang’E-3 lunar lander,
for which centrifugal, vibration, discharge, long term inverse pressure of diaphragm
tests were conducted.
1. Centrifugal Test
A real tank with actual installation interfaces and propellant load was used in
centrifugal tests in 3 status and 7 operation conditions totally. The test levels could
be classified into acceptance, qualification and marginal test level. Test conditions
covered longitudinal/transversal, longitudinal, transversal and reversal condition.
After tests, leak test and expulsion test were conducted. Parameters such as leakage
rate, expulsive efficiency and diaphragm overturn times satisfied the requirements,
and the anti-overload capabilities of tank shell and metal diaphragm were fully
verified.
2. Vibration Test
Two real tanks with actual installation interfaces and propellant load were used to
conduct vibration tests in acceptance and qualification level. One of the tanks was
simulated for propellant filling with tank evacuation and then passed vibration test
with simulant. After test, the leakage rate, expulsion, fatigue and burst performance
were examined to be normal. After 8 tanks individually passed full load acceptance
tests, they were installed on propulsion subsystem integrated on the lunar lander and
passed one acceptance test and one qualification test respectively. After then, propulsion subsystem hot firing test was conducted. Through vibration test and expulsion
test for several propellant tanks, the adaptability and reliability of the tank shell and
diaphragm were verified.
3. Expulsion Efficiency Test
In order to simulate influence of flow variation on tank expulsion during orbit control
engine operation in each flight phase, two tanks were used to conduct large flux expulsion within 0~80% of propellant consumption (simulating near LOI, main deceleration phase with constant thrust output of 7500 N throttling engine), tank expulsion
with flux varied continuously within 80~90% of propellant consumption (simulating
throttling thrust modulation in powered descent), and tank expulsion with constant
flux within 90~100% of propellant consumption (simulating 2000 N constant thrust
at the end of powered descent). The tank expulsion performance and reliability with
flux as in flight were fully verified.
4. Inverse Pressure-Bearing Test of Metal Diaphragm
To simulate long term inverse pressure-bearing capability of metal diaphragm under
saturated vapor pressure of MON-1 oxidizer after filled, two tanks were used to
conduct inverse pressure-bearing test of metal diaphragm. One of the tanks was
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strength and stiffness. A great many ground tests should be conducted including
shell load bearing, management device, discharge performance and reliability. For
example, the lightweight composite wrapped aluminum alloy diaphragm tanks fixed
at both ends were applied in propulsion subsystem of the Chang’E-3 lunar lander,
for which centrifugal, vibration, discharge, long term inverse pressure of diaphragm
tests were conducted.
1. Centrifugal Test
A real tank with actual installation interfaces and propellant load was used in
centrifugal tests in 3 status and 7 operation conditions totally. The test levels could
be classified into acceptance, qualification and marginal test level. Test conditions
covered longitudinal/transversal, longitudinal, transversal and reversal condition.
After tests, leak test and expulsion test were conducted. Parameters such as leakage
rate, expulsive efficiency and diaphragm overturn times satisfied the requirements,
and the anti-overload capabilities of tank shell and metal diaphragm were fully
verified.
2. Vibration Test
Two real tanks with actual installation interfaces and propellant load were used to
conduct vibration tests in acceptance and qualification level. One of the tanks was
simulated for propellant filling with tank evacuation and then passed vibration test
with simulant. After test, the leakage rate, expulsion, fatigue and burst performance
were examined to be normal. After 8 tanks individually passed full load acceptance
tests, they were installed on propulsion subsystem integrated on the lunar lander and
passed one acceptance test and one qualification test respectively. After then, propulsion subsystem hot firing test was conducted. Through vibration test and expulsion
test for several propellant tanks, the adaptability and reliability of the tank shell and
diaphragm were verified.
3. Expulsion Efficiency Test
In order to simulate influence of flow variation on tank expulsion during orbit control
engine operation in each flight phase, two tanks were used to conduct large flux expulsion within 0~80% of propellant consumption (simulating near LOI, main deceleration phase with constant thrust output of 7500 N throttling engine), tank expulsion
with flux varied continuously within 80~90% of propellant consumption (simulating
throttling thrust modulation in powered descent), and tank expulsion with constant
flux within 90~100% of propellant consumption (simulating 2000 N constant thrust
at the end of powered descent). The tank expulsion performance and reliability with
flux as in flight were fully verified.
4. Inverse Pressure-Bearing Test of Metal Diaphragm
To simulate long term inverse pressure-bearing capability of metal diaphragm under
saturated vapor pressure of MON-1 oxidizer after filled, two tanks were used to
conduct inverse pressure-bearing test of metal diaphragm. One of the tanks was