A New Approach to Designing the S-Shaped Annular Duct for Industrial Centrifugal Compressor

Table 1

Matrix of the 3³ design.

Input factors	Low-level (−1)	Mid-level (0)	High-level (+1)
	1.3	1.9	2.5
	1	1.5	2
	0.2	0.5	0.8