Converging-Diverging Nozzle

Introduction

The focal point of this assignment is to analyze flow features in the passage government in meeting diverging noses utilizing fluent. GAMBIT was used to make the mesh geometry. Solidworks CAD package was used to make the geometry. The Study will besides depict the method used for imitating flows and the specific geometry and flow conditions. Fluent has been used to pattern the fluid flow in a convergent-divergent nose.

Literature reappraisal

For this assignment, compressible flow through a convergent-divergent nose was modelled in FLUENT. For continency the theoretical account was represented in 2D which enclosed the flow sphere. The flow sphere was adjusted based on the dimension of the nose ( flow sphere representation ) . Due to the nature of the flow symmetricalness of the geometry, merely half of the full geometry was modelled.

An axisymmetric, converging-diverging nose with wall form made of round sections. The nozzle inlet/outlet and pharynx subdivisions are made of two circles. The recess and pharynx circles meet at a point with a common tangent organizing the recess wall of the nose and the fumes wall is tangent to the pharynx * circle. Figure 1 shows the general form of the nose. The nose has an mercantile establishment cross subdivision country of 2800mm2. The 2-D geometry is obtained based on the cross sectional countries flow boundary.

Flow Type

Because the flow has high Reynolds figure it is disruptive flow and K-epsilon was selected for the theoretical account. Overtime if the flow rate does non alter the system will be in equilibrium ( steady province ) but if it does it will be a transeunt solution. For this simulation we have a steady province solution.

Boundary Conditionss

Ethane gas was specified at the recess of the convergent divergent nose. The recess temperature was 341 K. A fixed unvarying mass flow 2.59 kg/s was specified at the recess. As mentioned antecedently axis symmetric boundary conditions were specified at the cardinal axis of the nose. The interior surfaces of the noses were specified as a wall. At the mercantile establishment the temperature, speed and force per unit area were specified.

Grid and Mesh Type

The cross subdivision country of the nozzle alterations non-uniform manure therefore the standard K- ? theoretical account has been used as it is the most suited theoretical account. The analysis were started by utilizing four-sided grid which can be can be farther refined for by grid adaptation technique.

Consequences

The analysis was performed to analyze dynamic C2H6 gas flow behavior in a convergent-divergent nose. On the recess, the flow was subsonic ( M=0.256 ) and as the flow accelerates at the pharynx it reaches to sonic ( M=1 ) and flux farther accelerate to super sonic ( M=1.25 ) in the divergent part. In divergent supersonic part the flow expands and daze moving ridge has been observed on the contour secret plan. The speed, temperature and force per unit area will besides be studied in the analysis

The undermentioned contour secret plans were obtained from the analysis taken topographic point during the lab Sessionss. The contour secret plans demonstrate the fluid flow inside a convergent divergent nose. The low-level formatting of the flow started at the recess force per unit area of 260000 Pa and speed of 85 m/sec.

Remainders

Remainders are the mistakes of the damaged equations. Remainders are calculated for each equation. Remainders should cut down as the numerical procedure advancements. They are frequently used to supervise the behaviour of the numerical procedure

The residuary secret plans show a convergence after about 28 loops.

Modeling Issues

Numeric Analysis

After making the mesh geometry on GAMBIT the flow simulation was done utilizing FLUENT. The theoretical account geometry was 2 dimensional axisymmetric. The simulation for force per unit area ration was performed and Figure 3 above were obtained. The theory was based on the premise of isentropic flow. The contour secret plan shows the flow in 2D.

This assignment shows how the usage of CFD package can be used to reenforce cardinal constructs of thermodynamics. It besides shows how the package ( Fluent ) can be used to look into the consequence of specific footings in the government equations.

In the theory every bit good as simulations, it was assumed that the flow is inviscid.

Decision

For simpleness this analysis was carried out on 2D, but the existent flow on 3D can be complex. All the flow features on 2D may non demo the flow right. The consequence can be less accurate. Other existent universe convergent-divergent fluid flow factors such as daze and after daze demand to be considered in order to accomplish a better truth.

Mentions

  1. “Numerical simulation on disruptive flow field in convergent-divergent Nozzle” Journal article, by LU Yi-yu, LIU Yong, LI Xiao-hong, KANG Yong, ZHAO Jian-xin