Simulation Of The Ventilation In Manned Spacecraft Cabin And Weight Reduction Analysis

The research on flow & heat exchange and ventilation system in manned spacecraft cabin is very important for normal operation of manned spacecraft. There have been random about airflow distribution design for spacecraft cabin, which needs systematic research. This article, taking spacecraft cabin as research objective, attempts to introduce verification and validation method of numerical simulation to analyze on convection simulation result of spacecraft cabin under microgravity with different turbulence models, and to provide reference for selection of appropriate turbulence model. Optimization analysis for mode of sidewall air supply which is usually adopted by great spacecraft is accomplished.Other air supply mode in spacecraft cabin is simulated and the characteristic and applicability in spacecraft cabin are analyzed. Then weight reduction for ventilation system is analyzed. Finally the reason of air distribution dissymmetry phenomena occurring in simulation and notability parameters are analyzed.First, convection and heat exchange characteristic of spacecraft cabin under microgravity is analyzed and the conceptual model including turbulence model and assistant model and numerical method are presented According to juvenility of model which is used for airflow simulation in spacecraft cabin and reliability requirement of ventilation system in spacecraft, verification and validation method is introduced to analyze convection and heat exchange simulation result with different models under microgravity and to provide reference for selection of suitable turbulence mode Thermal scale ratio technique is adopted to transform experiment data under gravity to that under microgravity due to lack of convection experiment data under microgravity in spacecraft cabin and the simulation result is validated with the transformed experiment data.Load of cooling, moisture and CO2 in spacecraft cabin are analyzed on basis of analyzing the requirement of temperature, relative humidity, air velocity, and concentration of CO2. Evaluation indexes of air distribution in spacecraft cabin are confirmed in order to evaluate the performance of various air distributions. Orthogonal test and variance analysis are used to analyze impact of air distribution mode, ratio of collocation, angle of air supply and ventilation rate on indexes of air distribution and to find the notable factors and the level optimum. The air supply mode of double sidewall air supplies with removed stagger opening, 50% ratio of collocation and 15 angle of air supply is considered to be better after analysis.Then, the performance of air distribution and applicability in spacecraft cabin of single sidewall air supply mode, diffuser air supply mode, and concentrated air supply mode with single opening which are maturely applied under gravity are analyzed. The task air conditioning system is set in workaround of cosmonauts to overcome the tediousness in cabin because of the lesser air velocity. The discrimination of air quality between task air conditioning system and routine air conditioning system is compared and find task air conditioning system may assure the air quality with the lesser ventilation rate, satisfying weight reduction principleBased on analyzing the main influence factors of ventilation system mass in spacecraft, air velocity in dust and size of dust is optimized with taking weight of duct and power consumption as target function. And the same time, the relation between system weight and ventilation rate is analyzed. The system weights of other dispose scheme of single sidewall air supply mode and double sidewall air supply mode are analyzed and compared. The system weight of round dust is also analyzed.Finally, the cause that dissymmetry phenomena is often occurs in plane jet of air but not in centralized jet is studied in theory through analyzing the function of Coanda effect in plane jet and centralized jet aiming at the dissymmetry phenomena of air distribution during simulation. The study is based jet theory and result of simulation. The notable factors impact dissymmetry phenomena is analyzed using Orthogonal test and variance analysis.