3D Modeling for Wet-Compression in a Single Stage Compressor Including Liquid Particle Erosion Analysis

Abstract

Gas turbine inlet fog / overspray cooling is considered as a simple and effective method to increase power output. To help understand the water mist transport in the compressor flow passage, this study conducts a 3-D computational simulation of wet compression in a single rotor-stator compressor stage using the commercial code, Fluent. A sliding mesh scheme is used to simulate the stator-rotor interaction in a rotating frame. Eulerian-Lagrangian method is used to calculate the continuous phase and track the discrete (droplet) phase respectively. Models to simulate droplet breakup and coalescence are incorporated to take into consideration the effect of local acceleration and deceleration on water droplet dynamics. Analysis on droplet history (trajectory and size) with stochastic tracking is employed to interpret the mechanism of droplet dynamics under the influence of local turbulence, acceleration, diffusion, and body forces. An liquid-droplet erosion model is included. The sensitivity of turbulence models on the results is conducted by employing 6 different turbulence models and 4 different time constants. The result shows that the local thermal equilibrium is not always achieved due to short residence time and high value of latent heat of water. Local pressure gradients in both the rotor and stator flow passages drive up the droplet slip velocity during compression. The erosion model predicts that the most eroded area occurs in leading edge and one spot of trailing edge of the rotor suction side.

Quantitative computational fluid dynamic analyses of oil droplets deposition on vaneless diffusor walls of a centrifugal compressor

“…Regarding the impact angle function, Nokleberg and Sontvedt suggested the value of in a piecewise linear manner between three data points for ductile materials as follows: f (0 deg) = 0, f (20 deg) = 1.0, and f (90 deg) = 0.3, and two points linear relationship for brittle materials between f (0 deg) = 0 and f (90 deg) = 1.0 …”

“…All three conditions could occur in areal application, but as FLUENT code only allows one condition to be assigned at a time, this study employs both reflected and filmed boundary conditions at separated cases, comparing the results of each. The results of the trapped condition should be between the results of the reflected and filmed conditions due to its allowance of water droplet evaporation upon surface contact . In this paper, the following conditions were adopted for the particle‐wall interaction boundary conditions: ideal adherence condition (named trap ) on the blade and diffusor surfaces; nonadherence condition (named reflect ) on other surfaces of the compressor.…”

“…Regarding the impact angle function, Nokleberg and Sontvedt suggested the value of f ( ) in a piecewise linear manner between three data points for ductile materials as follows: f (0 deg) = 0, f (20 deg) = 1.0, and f (90 deg) = 0.3, and two points linear relationship for brittle materials between f (0 deg) = 0 and f (90 deg) = 1.0. 46,47 For the restitution, the data were obtained by Whitaker et al 48 In that study, the authors found the restitution coefficients for glass beads impacting the aluminum plate. The restitution coefficient is dependent on the particle impingement angle α, and both the perpendicular and tangential components of the restitution coefficient should be considered.…”

“…The results of the trapped condition should be between the results of the reflected and filmed conditions due to its allowance of water droplet evaporation upon surface contact. 47 In this paper, the following conditions were adopted for the particle-wall interaction boundary conditions: ideal adherence condition (named trap) on the blade and diffusor surfaces; nonadherence condition (named reflect) on other surfaces of the compressor.…”

Entropy Generation and Efficiency of a Transonic Rotor With Water Injection: A Numerical Study

“…Khan & Wang [13,14], and Bugarin et al [15] analysed independently a single-stage axial compressor model by Hus and Wo [16] at design conditions, using 2D and 3D analysis. The focus in Ref.…”