Abstract:

Objective Two difficulties exist when studying the thermal protection performance of three-dimensional (3-D) spacer woven fabrics, which are the low repeatbility of the test results obtained from self-built platforms by themselves, and the high cost of samples in terms of forming process complexity, long lead time, and the production cost. In order to solve the above two problems, numerical simulation was carried out to save manpower and material resources, break through the limitations of experimental conditions, and reduce the error caused by human factors.

Method Parametric modeling of basalt/polyimide 3-D spacer woven fabric was carried out, and then its heat transfer mechanism in high temperature environments was analyzed. The control equation and boundary conditions were determined, and finite element analysis software was utilized to numerically simulate the geometric model of 3-D spacer fabrics in high temperature environments, in order to predict the influence of spacer height and weft spacing on the heat transfer performance of basalt/polyimide 3-D spacer woven fabrics.

Results From the heat transfer diagram of 3-D spacer woven fabrics with different weft spacing at an external ambient temperature of 150 ℃, it was evident that as the weft spacering was increased, the temperature on the back of the fabric gradually was found to decrease when the heat balance was reached. When the weft spacing increases from 5 to 23 mm, the temperature of the point probe on the back of the fabric demonstrated a decrease from 42.63 ℃ to 42.40 ℃ at the heat transfer equilibrium state. Inside the 3-D spacer woven fabric, the spacer yarn temperature on the same horizontal plane was slightly lower than the air domain temperature, with a difference of about 0.22 ℃. From the heat transfer numerical simulation diagram of different spacer heights, it was seen that as the spacer height increases, the temperature on the back of the 3-D spacer woven fabric showed a gradual decrease when the heat transfer reached equilibrium. When the spacer height was increased from 0 to 12 mm, the temperature of the point probe on the back of the fabric showed a decrease from 51.31 ℃ to 39.91 ℃ at the heat transfer equilibrium state. Inside the 3-D spacer woven fabric, the spacer yarn temperature on the same horizontal plane was slightly lower than the air domain temperature, with a difference of about 0.15 ℃.

Conclusion Parametric modeling is carried out according to the geometric relationship of basalt/polyimide 3-D spacer woven fabric structural unit, the buckling and the interweaving of yarns. Based on the basic theory of heat transfer, a numerical model of heat transfer process of basalt/polyimide 3-D spacer woven fabric in high temperature environment is established. The finite element analysis is carried out to calculate the temperature field of basalt/polyimide 3-D spacer woven fabric in high temperature environment. The numerical simulation method is adopted to explore the influence of the weft spacing on the heat transfer performance. The spacer height is found an important parameter affecting the heat transfer performance of the 3-D spacer woven fabric. The 3-D spacer fabric, the spacer yarn temperature on the same horizontal plane at the same time is slightly lower than the air domain temperature.

Key words: three-dimensional spacer woven fabric, basalt fiber, polyimide fiber, high-performance fiber, high temperature environment, heat transfer, numerical simulation