Numerical Investigation of Nozzle Geometry Effect on Turbulent 3-D Water Offset Jet Flows

Aliha, Negar Mohammad; Afshin, Hossein; Farhanieh, Bijan

doi:10.18869/acadpub.jafm.68.235.21386

Cited by 10 publications

(8 citation statements)

References 37 publications

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“…Circular, square, and rectangular nozzles were considered in [65]'s CFD study of the effects of nozzle geometry on turbulent offset jet development in the near-field region. Turbulence models that were studied include the standard k-ε model [66], the realizable k-ε model [67], the Launder-Sharma k-ε model [68], and the Yang-Shih k-ε model [69].…”

Section: Horizontal Jetsmentioning

confidence: 99%

CFD Modeling of Effluent Discharges: A Review of Past Numerical Studies

Mohammadian

Gildeh

Nistor

2020

Water

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Effluent discharge mixing and dispersion have been studied for many decades. Studies began with experimental investigations of geometrical and concentration characteristics of the jets in the near-field zone. More robust experiments were performed using Laser-Induced Fluorescence (LIF) and Particle Image Velocimetry (PIV) systems starting in the 20th century, which led to more accurate measurement and analysis of jet behavior. The advancement of computing systems over the past two decades has led to the development of various numerical methods, which have been implemented in Computational Fluid Dynamics (CFD) codes to predict fluid motion and characteristics. Numerical modeling of mixing and dispersion is increasingly preferred over laboratory experiments of effluent discharges in both academia and industry. More computational resources and efficient numerical schemes have helped increase the popularity of using CFD models in jet and plume modeling. Numerous models have been developed over time, each with different capabilities to facilitate the investigation of all aspects of effluent discharges. Among these, Reynolds-averaged Navier-Stokes (RANS) and Large Eddy Simulations (LES) are at present the most popular CFD models employing effluent discharge modeling. This paper reviews state-of-the-art numerical modeling studies for different types and configurations of discharges, including positively and negatively buoyant discharges, which have mostly been completed over the past two decades. The numerical results of these studies are summarized and critically discussed in this review. Various aspects related to the impact of turbulence models, such as k-ε and Launder-Reece-Rodi (LRR) models, are reviewed herein. RANS and LES models are reviewed, and implications for the simulation of jet and plume mixing are discussed to develop a reference for future researchers performing numerical investigations on jet mixing and dispersion.

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Section: Horizontal Jetsmentioning

confidence: 99%

CFD Modeling of Effluent Discharges: A Review of Past Numerical Studies

Mohammadian

Gildeh

Nistor

2020

Water

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“…They claimed that a good level of agreement was achieved, between the experiments and the calculations. Mohammadaliha and Farahanieh [19] focused attention on the influence of nozzle geometry on the evolution of a 3D incompressible turbulent offset jet. Their results imply that the spread rate, flow entrainment, and mixing rate of an offset jet issuing from a circular nozzle are lower than square-shaped one.…”

Section: Figure 1 Schematic Design Of Offset Jet Flowmentioning

confidence: 99%

Investigation of k-ε Turbulent Models and Their Effects on Offset Jet Flow Simulation

Boroomand

Mohammadi

2019

Civ Eng J

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In the case in which relatively low thickness and high-velocity flow enter into the lower velocity fluid, the resulting interference field of these two flows is called the jet. This phenomenon is the dominant output of power plants and some of the dams. The jets can be divided into two categories of free jets and confined jets, caused by the distance from the discharge to limited boundaries points. The offset jet is a type of confined jet in which both free surface and wall boundaries are near the diffusion location. The jet flow due to the extreme curvature in the main flow path and the proximal portion of this flow with solid boundaries have characteristics that make it difficult to solve with simple turbulence models.In this research, the offset jet phenomenon and related issues have been investigated. For this purpose, the offset jet flow pattern and probable factors in the complexity of this model have been simulated using Fluent software which analyses fluid flow in a two dimensional and three dimensional finite volume method. The simulation of offset jet flow pattern has been performed with a focus on investigating different models of turbulence k-ε, also boundary conditions, various wall functions and other effective coefficients in the numerical model and the model results compared with test case data findings and validating results, the necessary approaches in numerical simulation of this phenomenon for using in the next stages had been taken.

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“…In another study by Hu et al (2000), it is reported that lobbed nozzle offers improved mixing wherein the potential core length reduces by 16% indicating early interaction of the entrained fluid with exhaust jet core. Mohammadaliha et al (2016) studied three nozzle shapes (circular, square, rectangular) and found an increase in mass entrainment of around 8% for the square nozzle compared to circular nozzle. No advantage in mass entrainment was observed by changing the aspect ratio (upto 4) of the rectangular nozzle.…”

Section: Introductionmentioning

confidence: 99%

Effect of Slot-Guidance and Slot-Area on Air Entrainment in a Conical Ejector Diffuser for Infrared Suppression

Singh

Sinha

2019

JAFM

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A numerical study has been carried out on a new design of ejector diffuser (infrared suppression device). New design conceptualizes exploiting the shape of the slot openings. A circular arc is provided to guide the entrained fluid at the slot openings. Performance of guided-slot ejector diffuser (GED) has been compared with conventional (non-guided-slot) ejector diffuser (NGED) in terms of local and cumulative mass entrainment ratios, temperature distribution and static pressure recovery. Three slot-area variations are also studied, namely (i) increasing slot-area ranging 1 ≤ A0 ≤ 2.02, (0 A is area of 1 st slot) (ii) constant slot-area A0 = 1 and (iii) decreasing slot-area ranging 0.49 ≤ A0 ≤ 1. Simulations have been carried out at fixed Reynolds number Re = 1.3  10 5. It is observed that GED has 3.5% higher cumulative mass entrainment ratio than NGED. GED forms cold annulus region below ejector diffuser wall from 1 st slot onwards which results in wall temperatures being close to ambient temperature (300 K). Higher mass entrainment rate and lower wall temperatures make GED a better infrared suppression device but static pressure recovery is better in NGED (Cp = 0.79) compared to GED (Cp = 0.43). Slot-area study reveals that the performance of increasing slot-area for GED and NGED is superior then constant and decreasing slot-area configurations. The cumulative mass entrainment is 20% higher while static pressure recovery is 45% more for the increasing slot-area GED when compared to the decreasing slot-area GED.

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Numerical Investigation of Nozzle Geometry Effect on Turbulent 3-D Water Offset Jet Flows

Cited by 10 publications

References 37 publications

CFD Modeling of Effluent Discharges: A Review of Past Numerical Studies

CFD Modeling of Effluent Discharges: A Review of Past Numerical Studies

Investigation of k-ε Turbulent Models and Their Effects on Offset Jet Flow Simulation

Effect of Slot-Guidance and Slot-Area on Air Entrainment in a Conical Ejector Diffuser for Infrared Suppression

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