بررسي و تحليل عددي همزمان جريان اطراف پروانه و شناور زير دريايي

چكيده انگليسي :

113 Numerical Analysis of flow Around a Body and Propeller Ali Mohamad Momeni Rad Am momenirad@me iut ac ir May 24 2010 Department of Mechanical engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Ahmad Reza Azimian azimian@cc iut ac ir Abstract Today Submarines have many applications in military activities oil explorations and oceanography Prediction of hydrodynamic forces exerting on a submarine to dynamically control it and to select propulsion system is one of the important problems in the submarine design In the present work viscous incompressible and turbulent flow around a 5 blade propeller worked behind an underwater body is simulated using sliding mesh with unsteady flow consideration The governing equations are solved by means of a commercial code which is a general CFD software using finite volume methods Also a proper algorithm is used to obtain advance ratio of propeller working behind the body The unstructured grid generated around the submarine and propeller includes 17 000 000 tetrahedral cells with 12 boundary layer meshes Also flow around the propeller in openwater condition and around the body without propeller is simulated in order to compare results The unstructured grid around the propeller in openwater condition includes 2 100 000 and around the body includes 17 500 000 tetrahedral cells with 12 boundary layer meshes In order to validate this work flow around the submarine and propeller B series model is simulated separately The hydrodynamic forces are calculated and showed a good agreement with the experimental In body simulation the hydrodynamic coefficients of the forces acting on the body is estimated for submarine speed ranging from 1m s to 8 24 m s and flow angle of attack is zero It shows that submarine drag coefficient decreases when Reynolds number increases Investigation of flow in stern region of the submarine shows that fraction wake has a 15 reduction with increasing submarine velocity Simulation of the propeller in openwater condition shows that the thrust and torque coefficient acting on the propeller decrease with increasing advance ratio Study of thrust distribution in the radial direction of the blades reveals that at the outer 40 of the propeller there is about 60 of generated thrust while at the inner 20 there is only 4 of the generated thrust Investigation of flow in upstream region of the propeller shows that induced velocity of propeller decreases with increasing the advance ratio Simulation of the propeller when working behind the submarine shows that the low magnitude of trust and torque of each blade occur 4 times in 1 rotation of propeller and it is due to high axial velocity influenced by stern wings Although 4 stern wings make symmetrical wake field at the propeller plane wake of sail causes the effective wake field and fluctuating of blade forces to be disordered Result shows that the thrust and torque coefficient acting on the propeller working behind the body is less than the thrust and torque coefficient on the propeller in openwater condition at the same advance ratio Results also show that the maximum efficiency in propeller working behind the body corresponds to a lower value of advance ratio compared to a uniform inlet velocity distribution The hydrodynamic coefficient of the forces acting on the body with the propeller working behind is more than the hydrodynamic coefficient of the body without the propeller at the same Reynolds number Key Words Submarine Marine propeller Unsteady flow CFD Body and propeller interaction

مومني راد، علي محمد

بررسي و تحليل عددي همزمان جريان اطراف پروانه و شناور زير دريايي

شناور زير آبي , پروانه دريايي , جريان گذرا , ديناميك , سيالات محاسباتي , برهمكنش بدنه و پروانه