l*****e
发帖数: 594 | 1 想用一个电机带动三个叶片的风扇，转的很慢，最快不超过30rpm。有什么简单办法大
概估计一下电机需要的扭矩吗？每个叶片大概80g，0.3m长。 | l**********i
发帖数: 11748 | 2 angle of attack大概几度？
然后用那个空气阻力的公式大概估算一下
如果有电脑3D模型，用ansys、abaqus之类的模拟一下
如果有实际的模型，用torque gague测一下最方便了 | l*****e
发帖数: 594 | 3 感谢回复！ 简单的说，angle of attack 不变的话，转速越快需要的torque约大还是
约小？另外torque gague是可是设定转速然后读torque吗？
【在 l**********i 的大作中提到】
: angle of attack大概几度？
: 然后用那个空气阻力的公式大概估算一下
: 如果有电脑3D模型，用ansys、abaqus之类的模拟一下
: 如果有实际的模型，用torque gague测一下最方便了
| s******1
发帖数: 224 | 4 1,根据fan的直径，rpm先算出tip speed,
2,approximately measure blade outlet angle (relative to tangential direction), make velocity triangle, from absolute velocity's portion in tangential direction, then calculate how much power contribute to pressure increasement of the air
3,assume efficiency, depends on if it is forward or backward blade, curved or airfoiled blade, normally forward+curved efficiency is smaller than backward, let's say forward is about 50%, backward could be 60% or 70%, calcualte total power consumes by the fan
4, then get the torque from power/shaft radius
you don't have to use any software to get your torque for an approximate
calculation | w**n
发帖数: 175 | 5 if know cfm and rpm ---> torque
do not need to know angle/size of blade | l*****e
发帖数: 594 | 6 cfm? And how? Please, if I may ask.
【在 w**n 的大作中提到】
: if know cfm and rpm ---> torque
: do not need to know angle/size of blade
| l*****e
发帖数: 594 | 7 这个power contribute to pressure increment of the air 是叶片重力作功的平均功
率吗？一圈不是0吗？见笑，以前学的物理都忘了。谢谢！
direction), make velocity triangle, from absolute velocity's portion in
tangential direction, then calculate how much power contribute to pressure
increasement of the air
or airfoiled blade, normally forward+curved efficiency is smaller than
backward, let's say forward is about 50%, backward could be 60% or 70%,
calcualte total power consumes by the fan
【在 s******1 的大作中提到】
: 1,根据fan的直径，rpm先算出tip speed,
: 2,approximately measure blade outlet angle (relative to tangential direction), make velocity triangle, from absolute velocity's portion in tangential direction, then calculate how much power contribute to pressure increasement of the air
: 3,assume efficiency, depends on if it is forward or backward blade, curved or airfoiled blade, normally forward+curved efficiency is smaller than backward, let's say forward is about 50%, backward could be 60% or 70%, calcualte total power consumes by the fan
: 4, then get the torque from power/shaft radius
: you don't have to use any software to get your torque for an approximate
: calculation
| t**********6
发帖数: 565 | 8 这个怎么算？我也很感兴趣。。
【在 w**n 的大作中提到】
: if know cfm and rpm ---> torque
: do not need to know angle/size of blade
| l**********i
发帖数: 11748 | 9 如果是我，我会这么估算：
cfm可以知道mass flow rate
然后用0.25 pi D^2算出来面积
用这俩能算出来大概的速度
然后用 power=m_dot×(V^2)/2=角速度×torque
【在 t**********6 的大作中提到】
: 这个怎么算？我也很感兴趣。。
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