Abstract—An optimum L/D ratio is evaluated in the present study using fuzzy-set theory. The fuzzy set based methodology could easily consider many attributes concurrently, while deciding the specifications of the suddenly expanded supersonic fluid flow through a straight circular duct. The methodology can be easily extended to a situation involving diverse conflicting objectives. This study can be extended to different nozzles having different geometries with variations in Mach numbers, primary pressure ratio and area ratio. It is observed that L/D ratio is 6 for base pressure for Mach numbers of 1.58, 1.74, 2.06 and 2.23 , which is in very close agreement with the experimental results cited in the literature. This has been discussed with fuzzy logic as a tool for three area ratios 2.89, 6.00 and 10.00. The primary pressure ratio has been varied from 2.10 to 3.48 and L/D ratio has been varied from 1 to 6. From this analysis it is observed that L/D ratio 6 is the optimum needed keeping in view all the parameters like wall static pressure and pressure loss including base pressure
Index Terms—fuzzy logic, base pressure, supersonic flow, Mach number, area ratio, pressure ratio
Cite: K. M. Pandey and Amit Kumar, "Studies on Base Pressure in Suddenly Expanded Circular Ducts: a Fuzzy Logic Approach," International Journal of Engineering and Technology vol. 2, no. 4, pp. 379-386, 2010.