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Bora Kalpakli

Expert CFD Engineer

Can work in or around Heidelberg

  • 49.4094
  • 8.69472
  • Suggested rate £267 / day
  • Experience 7+ years
Propose a project The project will begin once you accept Bora's quote.

This freelancer is available full-time but hasn't confirmed their availability in over 7 days.

Propose a project The project will begin once you accept Bora's quote.

Location and workplace preferences

Location
Heidelberg, Germany
Can work onsite in your office in
  • around Heidelberg and 50km

Verifications

Freelancer code of conduct signed
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Verified email

Languages

  • English

    Conversational

  • Turkish

    Native or bilingual

Skills (11)

Bora in a few words



As a CFD engineer, I have worked as a design engineer for various types of combustion chambers, mineral separation devices, ventilation systems. I extensively utilized my fluid dynamics and CFD knowledge as a design engineer. I have three patent applications.
I have been developing a parallel CFD software (MPI-based, distributed memory) for my customers in the defense industry for more than ten years. This simulation software currently runs on half of the clusters available in relevant departments of my customers. The fully(strongly) coupled main solver of this software scales much better on the company's clusters than the similar commercial solvers for complex transient problems including multi-phase effects, turbulence, species transport, and conjugate heat transfer. For steady-state problems, this solver is better than the commercial codes such as Ansys Fluent, especially for highly compressible flows. I also constructed and administered Linux cluster systems for my customers. I also have been developing a special multi-material hydrocode as an ongoing project.

Experience

LIKUA

Energy & Utilities

Hydrocode for Internal Confinement Fusion Research  - As a freelancer

March 2018 - Today (4 years and 11 months)

In this project, I was responsible for analyzing interface instabilities between plasma gas and external structures. I used my own in-house Hydrocode solver to investigate the effects of these multi-dimensional interface instabilities on fusion conditions.
Compressible Multiphase Flows CFD C++

A defense company

Defense & Military

CFD developer  - As a freelancer

March 2015 - Today (7 years and 11 months)

In this work, I was responsible for developing a CFD code for full simulation of big solid rocket motors including particle effects. This code is based on the previous studies I had completed, and some extra models are added such as particle coalescence and breakup based on Interfacial Area Transport approach, which is a strong alternative to population balance models. This solver can solve both steady and time-accurate transient problems such as ignition transients. We are also using this solver for acoustic and hydrodynamic instability problems with particle effects. I also developed C++ types from scratch for fast automatic calculation of Jacobians based on operator overloading with some new methods available such as expression templates.
CFD C++

A Defense Company

Aviation & Aerospace

R&D  - As a freelancer

March 2012 - March 2016 (4 years)

I developed a detailed computational model for boron particle combustion in varying composition environments. The main application area of the model is Computational Fluid Dynamics (CFD) based simulations of solid propellant ramjet combustion chambers and it is aimed to construct a combustion model for boron-containing solid propellants. This model includes physical processes required to define a high fidelity particle combustion simulation. The combustion model consists of surface and gas-phase reactions for ignition and combustion of particles along with phase change processes including melting, evaporation, and boiling. The reaction rate modeling in similar studies are improved and corrected for ramjet combustion chambers and this model provides better predictions for all particle sizes. The reactions in ignition stage are reformulated as competing reactions for consumption of (BO)n polymers. Large discrepancies between experimental and calculated ignition times for small particles in previous models are eliminated. The developed model is added to a multi-dimensional CFD solver and is used along with gas-phase detailed turbulent combustion simulations of ducted rocket combustion chambers. This simulation approach provided a powerful and reliable design tool for side dump combustion chambers of ducted rockets with boron particle fuels. This detailed combustion model is validated with existing experimental results available in the open literature. The model is also compared with the results of similar studies.
Particle Combustion CFD

A Defense Company

Aviation & Aerospace

CFD Developer

March 2011 - March 2015 (4 years)

This was a NATO-STO support project in collaboration with ONERA/France (TU-AVT-10-P/1). I developed a fully implicit, fully coupled, unstructured finite volume (mixed elements) simulation software for turbulent combustion. I developed the code from scratch. All the equations are written in terms of primitive variables (pressure, velocity, temperature, turbulent parameters, and species mass fractions) and solved in a fully coupled manner. The coupled system of equations is solved using an unstructured collocated Finite Volume (FV) approach using a fully implicit temporal discretization. An all-speed version of the AUSM approach is used along with a time derivative preconditioning. Boundary conditions including wall functions are adapted to the algorithm. The developed fully coupled solver can be applied to a wide range of flow speeds from incompressible limit to hypersonic regimes. For solving the resulting system of equations, a sparse ILU preconditioned, sparse GMRES solver is used. This sparse matrix solver is very effective and only linearly increases the computational cost with an increasing number of solution cells and a number of solution variables. Turbulence reaction coupling is basically obtained using a hybrid Eddy Dissipation Model (EDM) approach. This is the only CFD code solving all the equations strongly coupled including turbulence and species transport. The thermally perfect gas thermodynamic properties are obtained automatically from the NASA database and fully linearized for implicit solutions. The fully implicit coupling of all equations in the form of primitive variables increased convergence rate and robustness radically.
CFD C++ Compressible Flow

A Defense Company

Aviation & Aerospace

Ramjet Combustion Chamber Design

March 2008 - March 2011 (3 years)

I was responsible for a ducted rocket ramjet combustion chamber design. I studied the main parameters and their effects on combustion efficiency for given missile flight profiles. I also studied solid fuel composition parameters including aluminum particles. This study included an optimized design of experiments on a blowdown test facility along with multi-physics simulations with detailed turbulent gas and particle-phase combustion and also with mechanical effects.
CFD Combustion

Education