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Yelocity-based lift coefficient calculations 11

5. BATCH PROCESSING

Designed program was additionally equipped with batch calculation modę. User can perform multiple calculations for various sizes of the integral curve. It was noticed that size of the bounding box has a significant influence on obtained lift results. An attempt of determining the optimal size of the integration rectangle used for calculations has been done. In order to do it a set of calculation was performed, both for various rectangle width-to-airfoil-chord (x/c) and rectangle height-to-chord (y/c) ratios (1-5-3 and 0.25*3, respectively). Exemplary lift results obtained fortwo angles of attack, a=5°, in the linear part of the characteristics (Tab. 1), and a=13° where airfoil is stalled (Tab. 2), are presented. The most representative values are highlighted for clarity.

Tab. 1 Lift coefficient results for angle of attack a=5°

a=5		x/c
		3	2,5	2,25	2	1,75	1,5	1,25	1
y/c	3	0,4553	0,4667	0,4723	0,478	0,4838	0,4894	0,495	0,5032
	2	0,4756	0,4836	0,4876	0,4916	0,4956	0,4995	0,5033	0,5027
	1	0,4989	0,5032	0,5052	0,5073	0,5094	0,5114	0,5133	0,5109
	0,75	0,5046	0,5077	0,5093	0,5109	0,5124	0,5139	0,5153	0,5125
	0,5	0,5111	0,5133	0,5144	0,5155	0,5165	0,5175	0,5183	0,5149
	0,375	0,5127	0,5144	0,5152	0,516	0,5168	0,5176	0,5182	0,5146
	0,25	0,5293	0,5181	0,5169	0,5171	0,5178	0,5187	0,5193	0,5158

Tab. 2 Lift coefficient results for angle of attack a=13°

d=13		x/c
		3	2,5	2,25	2	1,75	1,5	1,25	1
y/c	3	0,5597	0,5732	0,5799	0,5866	0,5944	0,6033	0,6137	0,6137
	2	0,5848	0,5941	0,5987	0,6033	0,6091	0,6159	0,624	0,6208
	1	0,6128	0,6175	0,6198	0,6221	0,6256	0,63	0,6358	0,6303
	0,75	0,6203	0,6237	0,6253	0,6269	0,6297	0,6334	0,6385	0,6322
	0,5	0,626	0,6283	0,6295	0,6305	0,6328	0,6361	0,6407	0,6339
	0,375	0,5315	0,5266	0,5268	0,5275	0,5298	0,5335	0,5403	0,5405
	0,25	-1,3655	-1,437	-1,4598	-1,4864	-1,4919	-1,4869	-1,4645	-1,4031

Data shown in the tables above can be visualised in the form of 3D surface plots, presenting the lift result response to changes of chosen parameters, producing varying lengths of the integration curve and, thereby, lift coefficient values (c_z on the plots in Fig. 2).