دانلود رایگان مقاله مطالعه عددی خنک کننده فیلم بر یک صفحه تخت با هدایت حرارتی ناهمسانگرد

abstract

Numerical study was performed to investigate the film cooling performance for a flat plate with anisotropic thermal conductivity where the plate had a single row of round holes. The cooling effectiveness and temperature distribution were analyzed and compared between the results of isotropic and anisotropic plates. The effects of two angles on the cooling effectiveness were studied, i.e. the axial angle a (0
, 30
, 35
, 60
and 90
) and the spanwise angle b (0
, 30
, 60
and 90
), with regards to the inclined angle between the main thermal conductivity in the plate and the mainstream flow direction. The results obtained showed that the anisotropy of the thermal conductivity and the inclined angles affected the cooling effectiveness in a complex way. The highest average cooling effectiveness could be achieved with a specific a or b, depending on the downstream region of the film cooling hole being considered. With the blowing ratio Br = 0.5, the highest cooling effectiveness averaged over the 0–5D and 0–20D downstream regions (with D the diameter of the film cooling hole) could be obtained with an angle of around 35
and 90
for a, respectively. It was found that the uniformity of the cooling effect was improved with a larger b. Moreover, the effects of a and b on the average cooling effectiveness were found to be similar with different Br. However, the uniformity was affected by a and b non-monotonically in different cases of Br. This work demonstrates that proper inclined angle can lead to better film cooling performance.

4. Conclusions

Numerical study was carried out on the film cooling from a single row of holes on a composite plate with focus on the effects of anisotropic thermal conductivity. The results of temperature, heat flux and cooling effectiveness were examined and discussed in detail. The effects of the inclined angles of the PDTC on the film cooling effectiveness were investigated. The main observations can be summarized as follows: (1) There are significant differences in the temperature fields between the adiabatic case and the conjugated heat transfer cases. The effects of anisotropic thermal conductivities are complex which significantly affect the temperature and heat flux flow fields. (2) Besides the effects of the discrete film holes and anisotropic thermal conductivity, the non-uniform temperature distribution was also influenced significantly by the inclined angle of the PDTC. The effects on the cooling effectiveness are complex and depend on the specific configurations of the inclined angles and thermal conductivity. (3) The highest average cooling effectiveness can be achieved with different values of a or b when different regions downstream of the film cooling are considered. We found that, when Br equals 0.5, the axial angle a should be around 35
in order to produce the highest average cooling effectiveness with focus on the 0– 5D downstream region. This value changes to 90
when the 0– 20D downstream region was considered. Compared with the axial inclined angle a, the span-wise inclined angle b had a weak influence on the average cooling effectiveness at the hot-side wall. However, the uniformity of the cooling effect can be improved with larger inclined angle b. (4) The effects of a and b on g are similar in different Br cases, but r is affected by a and b non-monotonically in different Br cases, especially when different downstream regions of film holes are considered.