Surface temperature reduction by using dimples/protrusions in a realistic turbine blade trailing edge

Figures & data

Figure 1. Wedge duct and dimple configurations. (a) Wedge configurations, (b) dimple configurations, (c) protrusion configurations.

Figure 2. Pin fin arrangement and those with dimples/protrusions positions. (a) pin fin arrangement, (b) case 1, 4, (c) case 2, 5, (d) case 3, 6. Pin fins-the white circles, dimples/protrusions-filled circles.

Figure 3. The schematic of the blade with dimples added between the pin fins at trailing edge.

Table 1. Details of the different cases.

	Cooling structure at trailing edge	Diameter of pin fin	Print diameter of dimple/protrusion	Dimple depth/protrusion height
Baseline	Pin fin	d	d	–
Case 7	Pin fin + dimple	d	d	0.2d
Case 8	Pin fin + dimple	d	d	0.3d
Case 9	Pin fin + protrusion	d	d	0.2d
Case 10	Pin fin + protrusion	d	d	0.3d

Figure 4. Boundary details of the conjugate heat transfer calculation.

Figure 5. Grids for wedge duct with pin fins and dimples (case 2). (a) 2D grids, (b) 3D grids.

Figure 6. The fluid and solid domain grid for cooling blade.

Figure 7. Mesh validation for blade calculation.

Figure 8. CFD validation.

Table 2. Averaged Nusselt number for different cases.

	Downstream	Upstream	Side-by-side
Dimple	4.12	4.66	4.67
Difference with downstream	–	13.11%	13.35%
Protrusion	4.21	4.69	4.94
Difference with downstream	–	11.40%	17.34%
Difference between dimple and protrusion	2.18%	0.64%	5.78%

Figure 9. Comparison of endwall heat flux distributions: (a) Case1, (b) Case2, (c) Case3, (d) Case4, (e) Case5, (f) Case6. Region A (black box).

Figure 10. Comparison of streamlines in relevant regions. (a) Case1, (b) Case2, (c) Case3, (d) Case4, (e) Case5, (f) Case6.

Figure 11. Comparison of TKE distribution in relevant regions. (a) Case1, (b) Case2, (c) Case3, (d) Case4, (e) Case5, (f) Case6.

Figure 12. Comparison of heat flux distribution in relevant regions. (a) Case1, (b) Case2, (c) Case3, (d) Case4, (e) Case5, (f) Case6.

Table 3. Comparison of one-dimensional parameters.

	Baseline	Case 7	Case 8	Case 9	Case 10
Average T for pressure side (K)	1117	1112	1107	1105	1110
Difference between baseline (K)	–	5	10	12	17
Average T for suction side (K)	1097	1092	1088	1088	1088
Difference between baseline (K)	–	5	9	9	14
for pressure side	0.366	0.372	0.379	0.382	0.388
Difference between baseline	–	0.007	0.013	0.016	0.022
for suction side	0.392	0.399	0.404	0.404	0.411
Difference between baseline	–	0.007	0.012	0.012	0.018
Mass flow for cooling inlet (g/s)	32.13	32.08	32.02	31.81	31.65
Difference between baseline (g/s)	–	0.05	0.11	0.32	0.48

Figure 13. Temperature (up) and wall heat flux (down) distributions on the pressure side inner face of blade trailing edge for different cases.

Figure 14. Streamlines, TKE, Wall heat flux and temperature distributions on the dimple of trailing edge pressure side.

Figure 15. Streamlines, TKE, Wall heat flux and temperature distributions on the protrusion of trailing edge pressure side.

Figure 16. Streamlines, TKE, Wall heat flux and temperature comparisons between dimple and protrusion for δ/d = 0.3 of trailing edge pressure side.

Figure 17. Temperature distributions on the blade surface pressure (upper) and suction (lower) side.