Structure and Velocity Measurements in Underexpanded Jets

Ewan, B. C. R.; Moodie, K.

doi:10.1080/00102208608923857

Cited by 149 publications

(76 citation statements)

References 4 publications

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“…Ivings et al [5] analyzed a number of approaches to represent the leak source. Their results showed that using the pseudo-source approach of Ewan and Moodie [13] gave good agreement with an empirical jet model. In this approach, the pseudo-source is assumed to be sonic, with the mass flow rate and temperature assumed to be the same as the vessel exit conditions but with a larger diameter.…”

Section: Initial and Boundary Conditionsmentioning

confidence: 61%

“…The gas expansion to atmospheric pressure takes place within a short distance, usually within 10-20 diameters [13]. It is usually unnecessary and prohibitive in terms of computational time to model such level of detail in a gas dispersion study.…”

Section: Initial and Boundary Conditionsmentioning

confidence: 99%

“…Leak source Underexpanded jets are created due to high pressure gas releases, i.e. the ratio of exit pressure to the ambient pressure is usually greater than 2 [13]. This creates a series of expansion and compression waves that culminates in a normal shock, which could create repeated patterns depending on the pressure ratio [13].…”

Section: Initial and Boundary Conditionsmentioning

confidence: 99%

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Validation of geometry modelling approaches for offshore gas dispersion simulations

Ahmed

Bengherbia

Zhvansky

et al. 2016

Journal of Loss Prevention in the Process Industries

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Computational Fluid Dynamics (CFD) codes are widely used for gas dispersion studies on offshore installations. The majority of these codes use single-block Cartesian grids with the porosity/distributed-resistance (PDR) approach to model small geometric details. Computational cost of this approach is low since small-scale obstacles are not resolved on the computational mesh. However, there are some uncertainties regarding this approach, especially in terms of grid dependency and turbulence generated from complex objects. An alternative approach, which can be implemented in generalpurpose CFD codes, is to use body-fitted grids for medium to large-scale objects whilst combining multiple small-scale obstacles in close proximity and using porous media models to represent blockage effects. This approach is validated in this study, by comparing numerical predictions with large-scale gas dispersion experiments carried out in DNV GLs Spadeadam test site. Gas concentrations and gas cloud volumes obtained from simulations are compared with measurements. These simulations are performed using the commercially available ANSYS CFX, which is a general-purpose CFD code. For comparison, further simulations are performed using CFX where smallscale objects are explicitly resolved. The aim of this work is to evaluate the accuracy and efficiency of these different geometry modelling approaches.

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Section: Initial and Boundary Conditionsmentioning

confidence: 61%

Section: Initial and Boundary Conditionsmentioning

confidence: 99%

Section: Initial and Boundary Conditionsmentioning

confidence: 99%

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Validation of geometry modelling approaches for offshore gas dispersion simulations

Ahmed

Bengherbia

Zhvansky

et al. 2016

Journal of Loss Prevention in the Process Industries

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show abstract

“…This barrel-shaped shock system prevents the entrainment of N 2 (Harstad and Bellan 2006), which allows for a single-component treatment of the flow up of the normal shock (Mach disk). For the present injection conditions, it can be assumed, furthermore, that the post-shock (index PS) pressure behind the Mach disk is equal to the chamber pressure p ch and that the immediate postshock temperature is approximately equal to T inj (Harstad and Bellan 2006;Ewan and Moodie 1986;Birch et al 1987).…”

Section: Measurement Conditionsmentioning

confidence: 99%

Mixing characterization of highly underexpanded fluid jets with real gas expansion

et al. 2018

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We report a comprehensive speed of sound database for multi-component mixing of underexpanded fuel jets with real gas expansion. The paper presents several reference test cases with well-defined experimental conditions providing quantitative data for validation of computational simulations. Two injectant fluids, fundamentally different with respect to their critical properties, are brought to supercritical state and discharged into cold nitrogen at different pressures. The database features a wide range of nozzle pressure ratios covering the regimes that are generally classified as highly and extremely highly underexpanded jets. Further variation is introduced by investigating different injection temperatures. Measurements are obtained along the centerline at different axial positions. In addition, an adiabatic mixing model based on non-ideal thermodynamic mixture properties is used to extract mixture compositions from the experimental speed of sound data. The concentration data obtained are complemented by existing experimental data and represented by an empirical fit.

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“…3,4,5,6,7 Experimental efforts have also been conducted to determine the Mach disk location and general shock geometry of under-expanded jets with a variety of experimental conditions, including a wide range of pressure ratios, nozzle contours, and working fluids. 8,9,10 Additionally, significant research efforts have focused on investigating boundary layer and shock interactions.…”

Section: Chapter 2 Backgroundmentioning

confidence: 99%

Planar Laser Induced Iodine Fluorescence Investigation of Mach 5 Jet-Jet and Jet-Jet-Surface Interactions

Barnes

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Structure and Velocity Measurements in Underexpanded Jets

Cited by 149 publications

References 4 publications

Validation of geometry modelling approaches for offshore gas dispersion simulations

Validation of geometry modelling approaches for offshore gas dispersion simulations

Mixing characterization of highly underexpanded fluid jets with real gas expansion

Planar Laser Induced Iodine Fluorescence Investigation of Mach 5 Jet-Jet and Jet-Jet-Surface Interactions

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