Validation of Gas Dynamic Virtual Nozzles using CFD techniques

Project Title

Validation of Gas Dynamic Virtual Nozzles using CFD techniques

Project Area of Specialization Mechanical EngineeringProject Summary

Gas Dynamic Virtual Nozzles are used in Serial Femtosecond Crytallography for the study of protien, bacteria and Virus structures. The femtosecond X-ray pulses from X-ray Free-Electron Laser (XFEL) are used to collect the diffraction patterns of protein microcrystals to determine their molecular structure. These samples are delivered into the X-ray interaction zone by Gas Dynamic Virtual Nozzles (Micro Nozzles). Our project is to validate computational fluid dynamics model for liquid micro jets. Such jets are produced by focusing hydrodynamic momentum from a co-flowing sheath of gas on a liquid stream in a nozzle. The computational model based on laminar two-phase, Newtonian, compressible Navier–Stokes equations is solved with finite volume method. A mixture model of the two-phase system is solved in axisymmetry using ~ 300,000 finite volumes. The numerical model will be evaluated by comparing jet diameters and jet lengths obtained experimentally and from computational analysis. 

Project Objectives

Our objectives are as Following:

• To develop a Computational model for Gas Dynamic Nozzle such that the jet Diameter is small as possible so as to reduce sample consumption.
• Velocity of jet is high as possible to avoid double X-ray exposure.
• Length of jet is as long as possible.

Project Implementation Method

Before the Computational part of our project we calculated different dimensionless and Geometerical parameters required, using the experimentally extracted data. Now we will perform the CFD analysis of GDVN. CFD of GDVN operation requires modeling of liquid and gas flow, surface tension forces on the interface, complex deforming topology at different scales, and inclusion of temperature and pressure-dependent material properties.Considering
the requirement to obtain a reliable contemporary solution of
the two-phase nozzle flow, compressible multiphase Open-
FOAM solver compressibleMultiphaseInterFoam will be used. The solver uses VOF to track the interface and FVM discretization with ability to efficiently handle both structured and unstructured meshes.

Benefits of the Project

The desire of an engineer to work on sample delivery has always been of paramount proportions. It was the team’s mutual consent to work on a project that would prove fruitful as an efficient method to develop the images of the molecular structure of proteins and viruses to study them which was not possible using different microscopes and other sample delivery techniques. Sample delivery using minimum diameter in a long jet with velocity as fast as possible is desirable which will have great results and could become breakthroughs in Mechanical and Biomedical Engineering and also in Structural Biology. Scope of this project presented many limitations during our work on this project. These limitations were the level of knowledge base acquired at the undergraduate level as well as the timeframe given for the completion of the project. Gas Dynamic Virtual Nozzles (GDVN’s) dimensions are in microns and only a few companies such as Fineline imaging can produce them. They are expensive and you can’t obtain them and perform on them. The Serial Femtosecond Crystallography (SFX) based labs are limited and few countries have those labs including European XFEL located in Hamburg Germany and SLAC laboratory located in the USA.

Technical Details of Final Deliverable

An axisymmetric CFD model, describing the performance of a ceramic molded micro-injection GDVN will be developed, where the converging geometry and the free expanding focusing gas shapes and stabilizes the jet. The computational details and a mesh independence study of the model will be presented. Compressible model will be used where two different viscosity models (constant and Sutherland). The model will provide a complete dynamical insight (as a
function of geometry, material properties and operating
conditions) into pressure, temperature, velocity and phasefraction fields that cannot be observed experimentally. A comparison with the experimental data in terms of jet
diameter and length wil be performed for a single geometric
nozzle arrangement with varying operating parameters.

Final Deliverable of the Project Software SystemCore Industry ManufacturingOther IndustriesCore Technology 3D/4D PrintingOther TechnologiesSustainable Development Goals Industry, Innovation and InfrastructureRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	80000
Computational Equipment	Equipment	1	70000	70000
Miscellaneous Cost	Miscellaneous	1	10000	10000