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5 Thermal Control Technology of Lunar Lander
5.6.2 VCHP Test
Generally, the function and performance of VCHP were verified in heat balance test
and mechanical test of the lunar lander. However, due to factors such as limited operation modes of instruments, it was inconvenient to conduct quantitative assessment
of heat transfer performance and operation characteristics in the test. Therefore, it
was generally necessary to conduct special tests for validation during key technology
validation phase.
1. Test Objectives
The major test objectives of vacuum performance of VCHP during key technology
verification phase are as follows:
(1) To measure the heat transfer capacity of VCHP during operation and verify
the heat transfer “blocking” capability at low temperature during lunar night.
(2) To study the effect of different heat source distribution in evaporation section
on the work characteristics and start-up process of the heat pipe;
(3) To study the working characteristics of VCHP during the wake-up process and
hibernation process.
2. Status of Test Article and Working Conditions
The shape of pipeline and the volume of gas tank should be considered for test article
of VCHP. Since the bending of pipeline will increase the flow resistance of fluid, the
heat transfer capacity could be reduced. It was impossible to test each type of heat
pipe. Therefore, the product with the most unfavorable working performance should
generally be selected for testing to ensure that the test result covered all products.
Since the condensing section of VCHP was generally embedded in the heatdissipating surface, there should be a piece of corresponding heat-dissipating surface
on test article to simulate the actual situation. The area of the simulated heatdissipating surface should be the same as the actual product. Generally, the electric
heater pasted on the body of heat pipe directly was selected for instrument on the
evaporation section. The size and configuration of the heater should simulate the
actual instrument. The heat consumption and operation modes of test article should
also be the same as the actual situation.
The effect of landing attitude on performance of VCHP should be considered when
the status of test article was determined. Generally, the test should be conducted on
the most unfavorable landing attitude.
During the test, the temperature of the condensation section was used to determine
the location of the vapor-control gas interface. The temperature measurement point
distribution should consider the possible location of the interface. In order to obtain
accurate temperature distribution, more temperature measurement points should be
arranged in the condensation section, which could provide sufficient data for determination of vapor-control gas interface, calculation of heat dissipation capacity and
correction of thermal analysis models. In addition, the heat leak test in lunar night
was also an important objective of the test and the temperature measurement points
5 Thermal Control Technology of Lunar Lander
5.6.2 VCHP Test
Generally, the function and performance of VCHP were verified in heat balance test
and mechanical test of the lunar lander. However, due to factors such as limited operation modes of instruments, it was inconvenient to conduct quantitative assessment
of heat transfer performance and operation characteristics in the test. Therefore, it
was generally necessary to conduct special tests for validation during key technology
validation phase.
1. Test Objectives
The major test objectives of vacuum performance of VCHP during key technology
verification phase are as follows:
(1) To measure the heat transfer capacity of VCHP during operation and verify
the heat transfer “blocking” capability at low temperature during lunar night.
(2) To study the effect of different heat source distribution in evaporation section
on the work characteristics and start-up process of the heat pipe;
(3) To study the working characteristics of VCHP during the wake-up process and
hibernation process.
2. Status of Test Article and Working Conditions
The shape of pipeline and the volume of gas tank should be considered for test article
of VCHP. Since the bending of pipeline will increase the flow resistance of fluid, the
heat transfer capacity could be reduced. It was impossible to test each type of heat
pipe. Therefore, the product with the most unfavorable working performance should
generally be selected for testing to ensure that the test result covered all products.
Since the condensing section of VCHP was generally embedded in the heatdissipating surface, there should be a piece of corresponding heat-dissipating surface
on test article to simulate the actual situation. The area of the simulated heatdissipating surface should be the same as the actual product. Generally, the electric
heater pasted on the body of heat pipe directly was selected for instrument on the
evaporation section. The size and configuration of the heater should simulate the
actual instrument. The heat consumption and operation modes of test article should
also be the same as the actual situation.
The effect of landing attitude on performance of VCHP should be considered when
the status of test article was determined. Generally, the test should be conducted on
the most unfavorable landing attitude.
During the test, the temperature of the condensation section was used to determine
the location of the vapor-control gas interface. The temperature measurement point
distribution should consider the possible location of the interface. In order to obtain
accurate temperature distribution, more temperature measurement points should be
arranged in the condensation section, which could provide sufficient data for determination of vapor-control gas interface, calculation of heat dissipation capacity and
correction of thermal analysis models. In addition, the heat leak test in lunar night
was also an important objective of the test and the temperature measurement points