不同温度下巨嘴鸟喙自然对流换热的数值研究

doi:10.7523/j.ucas.2024.027

摘要/Abstract

摘要：

针对托哥巨嘴鸟鸟喙结构特殊和换热能力强的特点，采用自然对流数值模拟的方法分别对其在30 ℃和15 ℃ 2种极端环境中的换热展开研究。沿长度方向截取鸟喙不同位置的温度云图，结果表明：高温环境下鸟喙的换热强度更大；而低温环境中只在颅骨附近出现明显的温度边界层。这是由于低温环境的局部瑞利数（Ra_x ）在颅骨附近剧烈变化，而在喙前中段Ra_x 较小以致该处对流换热现象不明显。通过流线图发现，高温环境中尖端的卷吸作用一定程度上改善了因喙尖的小面积所引起的换热量不足，充分发挥了喙的每一块散热面积的作用；低温环境的鸟喙卷吸效应集中于颅骨附近，不可避免地造成部分热量损失。3个无量纲数C_p 、C_f 和Nu的分析结果表明，2种环境下上颌骨区域C_p 皆为负值，促使冷空气汇入边界层内，改善了由于预热效应而引起的小温差对换热的缺陷。特别在低温环境下，鸟喙前中部的C_p 和C_f 几乎为0，同时Nu稳定于一个较小值，以减少自身热量散失。

关键词: 巨嘴鸟, 鸟喙换热, 自然对流, 生物传热

Abstract:

This study investigates the heat transfer characteristics of the Toco Toucan’s beak， which is known for its unique structural features and strong heat exchange capabilities， using natural convection numerical simulations in environments of 30 ℃ and 15 ℃， respectively. Temperature contours at different positions along the length of the beak were extracted. It was observed that the heat transfer efficiency of the beak is higher in high-temperature environments， whereas in low-temperature environments， only a distinct temperature boundary layer near the skull is evident. Analysis revealed significant variations in the local Rayleigh number （Ra_x ） near the skull in low-temperature environments， while Ra_x in the anterior midsection of the beak remains relatively small， resulting in less pronounced convective heat exchange in this region. Streamline diagrams illustrate that in high-temperature environments， the entrainment effect at the tip of the beak alleviates the heat exchange deficiency caused by the small surface area， effectively utilizing every part of the beak’s dissipating surface. However， in low-temperature environments， the entrainment effect of the beak is concentrated near the skull， resulting in inevitable heat loss. By analyzing three dimensionless numbers， C_p， C_f， and Nu， it was found that C_p values in the Maxilla are negative in both environments， promoting the influx of cold air into the boundary layer and improving heat exchange efficiency by reducing temperature differentials caused by preheating effects. Particularly in low-temperature environments， C_p and C_f_{values in the anterior midsection of the beak are almost zero， while Nu stabilizes at a relatively small value， minimizing heat loss from the beak’s surface. The above research results quantitatively elucidated the heat exchange characteristics of bird beaks. Through further studies， it is hoped to provide reference for exploring the geographical distribution of toucans.}

Key words: Toucan, beak heat exchange, natural convection, biological heat transfer

中图分类号:

TK124

黄兴, 穆建超, 刘捷, 郝彦宾. 不同温度下巨嘴鸟喙自然对流换热的数值研究[J]. 中国科学院大学学报, 2026, 43(1): 33-41.

Xing HUANG, Jianchao MU, Jie LIU, Yanbin HAO. Numerical investigation of natural convection heat transfer for toucan beak with different temperatures[J]. Journal of University of Chinese Academy of Sciences, 2026, 43(1): 33-41.

图/表 8

图1 鸟喙三维模型

Fig. 1 3D model of a beak

图2 鸟喙模型图

Fig. 2 Beak model diagram

表 1 单水平圆柱自然对流模型验证

Table 1 Validation of a single horizontal cylindrical natural convection model

Ra	$N u ¯$	$N u r e f ¯$ ^[15,21-22]	相对偏差/%
10³	3.14	3.11	0.96
10⁴	5.02	4.80	4.58
10⁵	8.33	8.54	2.46

表 1 单水平圆柱自然对流模型验证

Table 1 Validation of a single horizontal cylindrical natural convection model

Ra	$N u ¯$	$N u r e f ¯$ ^[15,21-22]	相对偏差/%
10³	3.14	3.11	0.96
10⁴	5.02	4.80	4.58
10⁵	8.33	8.54	2.46

图3 正视、侧面剖视和边界层网格图

Fig. 3 Front-face， side-sectional， and boundarylayer grid diagrams

表 2 网格和区域无关性验证

Table 2 Grid and region independence validation

网格量	区域 (D×S×B)	最小网格尺寸/mm	$N u ¯$
3 678 190	7H×7.5C×2L	0.4	9.200
4 176 056	7H×7.5C×2L	0.2	9.196
4 772 984	9H×9C×2L	0.4	9.209

表 2 网格和区域无关性验证

Table 2 Grid and region independence validation

网格量	区域 (D×S×B)	最小网格尺寸/mm	$N u ¯$
3 678 190	7H×7.5C×2L	0.4	9.200
4 176 056	7H×7.5C×2L	0.2	9.196
4 772 984	9H×9C×2L	0.4	9.209

图 4 鸟喙温度云图

Fig. 4 Isothermal contours of the beak

图5 不同温度环境流线图

Fig.5 Streamline for the different environments

图6 3个无量纲系数

Fig.6 Three dimensionless coefficients

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