Large eddy simulation of flow around a reverse rotating propeller

Abstract

This paper studies the flow around a propeller rotating in the reverse direction in a uniform free stream. Large eddy simulation is used to study this massively separated flow at a Reynolds number of 480 000 and advance ratios $J= - 0. 5$, $- 0. 7$ and $- 1. 0$. Simulations are performed on two grids; statistics of the loads and velocity field around the propeller show encouraging agreement between the two grids and with experiment. The impact of advance ratio is discussed, and a physical picture of the unsteady flow and its influence on the propeller loads is proposed. An unsteady vortex ring is formed in the vicinity of the propeller disk due to the interaction between the free stream and the reverse flow produced by the reverse rotation. The flow is separated in the blade passages; the most prominent is the separation along the sharp edge of the blade on the downstream side of the blade. This separation results in high-amplitude, transient propeller loads. Conditional averaging is used to describe the statistically relevant events that determine low- and high-amplitude thrust and side-forces. The vortex ring is closer and the reverse flow induced by propeller rotation is lower when the loads are high. The propeller loads scale with $\rho {U}^{2} $ for $J\lt - 0. 7$ and with $\rho {n}^{2} {D}^{2} $ for $J\gt - 0. 7$.

The effect of an upstream hull on a propeller in reverse rotation

“…3.1. Propeller without a hull at J = −0.7 The validity of the current LES methodology for propeller crashback is established by the LES of propeller without a hull at J = −0.7 by Jang & Mahesh (2012) which is in good agreement with the experimental results of Jessup et al (2004Jessup et al ( , 2006. Computed mean K T and K Q are located between the 36 in.…”

“…Simulations are performed for a marine propeller DTMB 4381, which is a five-bladed, right-handed propeller with variable pitch, no skew and no rake. The propeller has been used in various experiments (Jiang et al 1997;Jessup et al 2004Jessup et al , 2006 and computations (Davoudzadeh et al 1997;Chen & Stern 1999;Vyšohlid & Mahesh 2006;Chang et al 2008;Jang & Mahesh 2012). For the hull geometry, a standard axisymmetric hull (DTMB Model 5495-3) is used.…”

“…They also used the LES surface forces to predict shear stress and bending moments on the blades and obtained good agreement with experiments. Jang & Mahesh (2012) introduced two quantities to describe pressure contributions to thrust and side force and observed that most of the thrust and side force originated from the suction side of the leading edge of the propeller blades. In the present work, flow past a propeller attached to an upstream hull, operating in the crashback condition is considered.…”

A numerical study of shear layer characteristics of low-speed transverse jets

“…The solution is advanced using a predictor-corrector methodology where the velocities are first predicted using the momentum equation alone, and then corrected using the pressure gradient obtained from the Poisson equation yielded by the continuity equation. The algorithm has been validated for a wide range of complex problems which include a gas turbine combustor geometry ) and predicting propeller crashback (Verma, Jang & Mahesh 2012;Jang & Mahesh 2013). It has been used to study the entrainment from free jets by (Babu & Mahesh 2004) and was applied to transverse jets by Muppidi & Mahesh (2005 and Sau & Mahesh (2007.…”

A DES-SST Based Assessment of Hydrodynamic Performances of the Wetted and Cavitating PPTC Propeller

“…Although the direct numerical simulation, in which the whole range of spatial and temporal scales of the turbulence are resolved, is by far the most accurate, it still remains the least attractive one because of its prohibitive computational costs. As an alternative, large eddy simulation (LES), in which the smallest length scales, which are the most computationally expensive to resolve, are simply ignored by filtering the governing equations, gained in popularity recently [9][10][11].…”