CN-121997795-A - Design method for internal flow gap of thermal control mechanical pump

CN121997795ACN 121997795 ACN121997795 ACN 121997795ACN-121997795-A

Abstract

A design method of internal flow gap of heat control mechanical pump includes setting initial value of each gap in mechanical pump, setting up full-flow-field simulation calculation model of mechanical pump rotor to carry out CFD simulation calculation to obtain pressure distribution, temperature distribution, cooling flow and axial force of bearing of cooling fluid in mechanical pump at each position of cooling flow channel, comparing fatigue life and wearing life of bearing, running efficiency of mechanical pump and supercooling degree of working medium at lee surface of back bearing with design requirement in sequence, and finishing final gap design by continuously adjusting each gap value. The invention realizes the fine control of cooling flow and pressure distribution by controlling the gap of the cooling flow channel in the pump, can ensure the high-efficiency cavitation resistance of the mechanical pump and improves the reliability of the mechanical pump.

Inventors

ZHAO LIANG
MIAO JIANYIN
Che Bangxiang
ZHENG HONGYANG
CAO JIANFENG
YU XINGANG
YANG MIN
WANG DEWEI
NIU CHUNYANG
XU KAN

Assignees

北京空间飞行器总体设计部

Dates

Publication Date: 20260508
Application Date: 20251210

Claims (10)

1. A design method of an internal flow gap of a thermal control mechanical pump is characterized by comprising the following steps: (1) Setting the clearance between the inner vane and back of mechanical pump Stator-rotor gap Gap at shaft end Diameter of reflux hole Diameter of jet hole And jet hole angle Is set to an initial value of (1); (2) Establishing a full-drainage-basin simulation calculation model of a mechanical pump rotor; (3) Performing computational fluid dynamics simulation calculation by using a model to obtain pressure distribution, temperature distribution, cooling flow and axial force applied to a bearing of cooling fluid in the mechanical pump at each position of a cooling flow channel; (4) Checking whether the fatigue life and the wear life of the bearing meet the requirements according to the axial force applied to the bearing, if so, entering a step (5), otherwise, returning to the step (1) to adjust the initial value until the fatigue life and the wear life of the bearing meet the requirements; (5) Analyzing whether the operation efficiency of the mechanical pump meets the requirement according to the cooling flow, if so, entering the step (6), otherwise, returning to the step (1) to adjust the initial value until the operation efficiency of the mechanical pump meets the requirement; (6) According to the pressure and temperature of the back bearing lee surface, analyzing the supercooling degree of the working medium at the back bearing lee surface If the requirement is met, finishing the gap design, otherwise, returning to the step (1) to adjust the initial value until the supercooling degree of the working medium at the lee surface of the rear bearing Meets the requirements.
2. The method for designing an inner flow gap of a heat control mechanical pump according to claim 1, wherein the back clearance is The design value range is 0.5-2 mm, and the stator and rotor clearance is between The design value range of (2) is 0.2-2 mm, shaft end gap The design value range is 0.5-3 mm, and the diameter of the backflow hole The design value range is 1-2 mm, and the diameter of the jet hole The design value range is 0.5-1 mm, jet hole angle The design value range of (2) is 30-60 degrees.
3. The method for designing the internal flow gap of the thermal control mechanical pump according to claim 1, wherein the method for obtaining the axial force borne by the bearing is characterized in that the impeller, the guide cap and the rotating shaft are used as analysis objects, the acting force of the fluid on each component is calculated through the fluid pressure of the fluid on the surface of each component, the component of the acting force along the axial direction of the rotating shaft is the axial force of the fluid on the component, the axial force borne by each component is synthesized, namely the axial force borne by the impeller, the guide cap and the rotating shaft is obtained, and the axial force borne by the whole acts on the bearing finally, and is the axial force borne by the bearing.
4. The method of claim 1, wherein in the step (4), if the step (1) is returned, the method of adjusting is to reduce the back clearance of the impeller To reduce axial forces, or to reduce back clearance of impellers To reduce the axial force while increasing the bearing diameter to increase the load carrying capacity of the bearing.
5. The method of claim 1, wherein in the step (5), if the flow returns to the step (1), the flow gap is adjusted by adjusting the diameter of the return hole And jet hole diameter The pressure drop of the leakage fluid passing through the reflow hole is increased, and the leakage quantity is reduced.
6. The method for designing a flow gap in a thermally controlled mechanical pump as set forth in claim 1, wherein said cooling flow is a total flow The cooling flow takes up the total flow While when the total flow rate The cooling flow takes up the total flow 。
7. The method for designing the internal flow gap of a heat control mechanical pump according to claim 1, wherein the back bearing has a working medium supercooling degree at the lee side Specifically, it is Wherein Is the temperature at the lee surface of the rear bearing, For obtaining the pressure of the leeward surface of the rear bearing by inquiring the manual of the physical properties of the working medium The corresponding working medium saturation temperature.
8. The method for designing the internal flow gap of a heat control mechanical pump according to claim 7, wherein the back bearing has a working medium supercooling degree at the lee side Satisfies the following conditions Degrees celsius.
9. The method of claim 1, wherein in the step (6), if the step (1) is returned, the corresponding adjustment is performed by increasing the stator/rotor gap Or reduce the end play 。
10. The method for designing the internal flow gap of the thermal control mechanical pump according to claim 1, wherein the checking of the fatigue life and the wear life of the bearing is performed by adopting an L-P equation or an ANSI equation.

Description

Design method for internal flow gap of thermal control mechanical pump Technical Field The invention belongs to the technical field of aerospace thermal control, and relates to a mechanical pump used for a spacecraft thermal control pump driving fluid loop. Background The pump driving fluid loop system has unique technical advantages in facing application requirements of high power, high heat flux, long-distance heat transport and the like of future aerospace tasks. The mechanical pump (hereinafter referred to as mechanical pump) of the pump driving fluid circuit is a core component of the heat control pump driving fluid circuit of the spacecraft, is the only high-speed movement equipment, provides driving force for working medium flow, and has certain cavitation resistance. From the current mechanical pump products or prototypes developed in countries around the world, the overall characteristics of a mechanical pump can be summarized as follows: 1) In the aspects of overall structure and rotary sealing treatment, in order to ensure safety, reliability and maintenance-free performance, a leakage-free pump structure form of a magnetic transmission or shielding structure is adopted; 2) Because of adopting a shielding structure, the motor rotor is completely immersed in the working medium, on one hand, the heat of the motor needs to be taken away through the convective heat exchange of the working medium, and on the other hand, the working medium is used as a lubricating medium to provide auxiliary lubrication for the bearing; 3) In the impeller and related flow passing component structure, considering the adaptability to small flow and high lift and cavitation problem, a composite impeller structure with long and short blades combined is generally adopted, and an inducer is partially adopted to improve the cavitation resistance. Because the mechanical pumps are all shielding pumps, the whole shaft system of the rotor is immersed in working medium, and partial flow in the pumps enters the shaft system along the clearance between the blade backs, thereby providing auxiliary lubrication for the bearings and taking away heat generated by the operation of the motor. The part of cooling flow flows back to the impeller inlet from the inside of the rotating shaft, so that circulation is formed. The cooling flow is required to at least meet the heat dissipation requirement of the motor, the motor temperature is not too high, meanwhile, the temperature rise of the cooling flow is not too high, otherwise, the working substance used by the mechanical pump is easy to generate cavitation at the lower bearing, but the cooling flow is not too high, the partial cooling flow is actually the internal circulation of the pump and does not work externally, and the excessive flow can cause the problems of pump efficiency reduction, axial force increase and the like. Therefore, the internal cooling flow and pressure distribution of the mechanical pump need to be finely controlled. In the on-orbit application process of the mechanical pump, the pump failure caused by unreasonable internal flow design occurs for a plurality of times. On the 31 th year of 2010, one power control unit of the international space station is shut down when being subjected to a large current impact, and the mechanical pump of the main loop is stopped. The cooling fluid which is positioned in the pump motor has only one drain hole at the rear bearing, through which the cooling fluid forms a jet to act on the shaft. It was analyzed that at 12500rpm, the radial imbalance force of the shaft caused by this jet had exceeded the bearing radial load capacity, ultimately leading to bearing wear failure. Another example is the mechanical pump used by AMS02, launched into service in 2011, with bearings originally designed for long life with sliding bearings. After the journal of the sliding bearing runs at high speed, dynamic pressure is formed by the internal working medium, and the journal is supported. However, after 4 years of on-orbit operation, the supercooling degree of the inlet working medium is insufficient due to the degradation of the coating performance, the partial pressure of liquid in the sliding bearing is lower than the saturated vapor pressure, cavitation is generated, a stable liquid film support cannot be formed in the sliding bearing, and the dynamic and static rings of the bearing are in contact abrasion failure. Disclosure of Invention The invention solves the technical problems that: aiming at the problem of fine control of cooling flow and pressure distribution in the mechanical pump, a design method of an internal flow gap of the mechanical pump is provided, and the cooling flow and the internal pressure distribution are finely controlled through the design of the internal flow channel and the shafting gap of the pump, so that the operation efficiency and cavitation resistance of the mechanical pump are improved, and the reliable and stable