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发表于 2008-3-27 07:34:15
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来自 台湾
回复 15/16/17# 的帖子
1. ===>一般轴流风机的长度比较小,在入口和出口处的流动都很不稳定,所有有技术咨询说是可以在仿真分析建模时适当延长风机的入口和出口段,就如同楼主所建模那样,我分析了后发现延长的模型和实际上比较短的模型结果差异还是比较大的,哪个更可信呢?
not exactly, depends on what condition you want to simulate, for example, you want to simulate a fan blade only, no ducts, then you should create a big domain to enclose fan blade, no ducts anymore. if you want to compare with experimental data, then you should follow the test stand setup to determine what kind of domain you need
2===>.另外,在分析的时候,把入口和出口都设成自由边界,也是可以计算得到结果的,算了200——300步,没有完全收敛到10-4,这样的结果可信度呢
depends,you should try to work hard to let it converge as good as possible before you say "it's 没有完全收敛到10-4", for ex. Did you try hard to make your mesh better, did you try hard to adjust the time step, the relaxation factor,........ to let it converge better? if you did,and the force is stable, then you can trust it to some level
coz the outlet duct length, will cause pressure loss to some level, especially for high flow speed cases.
so you should determine the pratical condition you want.
3.==>后处理结果中如何得到风机的一个指标,全压呢,流量如何计算?
? , should be easy to obtain in cfx-post, you can try it
4.==>关于出口的设置有个问题,出口设置成OUTLET,我今天看到一个类似课题的资料,是把出口设置成OPENING,请问用哪种类型设置出口更好更准确呢??谢谢!!
you should know that what is "Opening" first
if air flow "INTO" domain, then what is the "property"(pressure, temperature....) of the incoming fluid?
it will use your pre-specified property which may not be correct.
so if you can use Outlet , dont use opening, but if "Outlet" is impossible, then use Opening
[ 本帖最后由 Kiddosuper 于 2008-3-27 07:35 编辑 ] |
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