Ragnar Larusson

Doktorand at Chalmers, Mechanics and Maritime Sciences, Fluid Dynamics

Since January 2012, Ragnar has been immersed in the compressible and supersonic world of internal flows in rocket engine nozzles. His work is focused on the infamous side-load problem. Here is a sneak preview from his upcoming paper that describes, in short, this side-load problem; "Modern space vehicles take off using a combination of solid rocket boosters and rocket engines. During the startup of a rocket engine at sea level the flow separates from the nozzle wall because of the over expansion of the nozzle. This creates an attached shock inside the nozzle and due to the sudden pressure rise across the attached shock, any asymmetry of the shock location along the circumference of the nozzle can cause side loads, potentially harmful to the nozzle structure and the engine"This phenomenon described above has been extensively researched over the past decades. The current research project that Ragnar is involved in aims to add to the existing and limited understanding of the phenomenon by means of advanced numerical simulation methods. The Swedish National Space Board is greatly acknowledged for funding the project, as is GKN Aerospace Engine Systems in Trollhättan for technical guidance. Supervising the project are Niklas Andersson and Lars-Erik Eriksson at Chalmers and Jan Östlund at GKN.Ragnar's Academic BackgroundRagnar holds a B.Sc. Degree in mechanical engineering from the University of Iceland. He earned his M.Sc. Degree in solid and fluid mechanics from Chalmers in 2011. During his masters thesis work and after graduation he had a brief encounter with external flow simulations around bluff bodies such as a rudimentary airplane landing gear and pyramids. In that work he used the Large Eddy Simulation method and the new and exciting Partially Averaged Navier-Stokes method.

Source: chalmers.se

Projects

2012–2014

Modal Decomposition of Separated Nozzle Flow

Lars-Erik Eriksson Fluid Dynamics
Niklas Andersson Fluid Dynamics
Ragnar Larusson Fluid Dynamics
Swedish National Space Board

There might be more projects where Ragnar Larusson participates, but you have to be logged in as a Chalmers employee to see them.

Publications

2017

Modal Analysis of Supersonic Flow Separation in Nozzles

Ragnar Larusson
Doctoral thesis
2017

Dynamic Mode Decomposition Applied to a Detached-Eddy Simulation of Separated Nozzle Flow

Ragnar Larusson, Markus Olander Burak, Niklas Andersson et al
Conference contribution
2017

Dynamic Mode Decomposition Applied to a Detached-Eddy Simulation of Separated Nozzle Flow

Ragnar Larusson, Markus Olander Burak, Niklas Andersson et al
Conference contribution
2017

Dynamic Mode Decomposition of a Separated Nozzle Flow with Transonic Resonance

Ragnar Larusson, Niklas Andersson, Jan Östlund
AIAA Journal. Vol. 55 (4), p. 1295-1306
Journal article
2016

Hybrid RANS-LES Simulation of Separated Nozzle Flow

Ragnar Larusson, Niklas Andersson, Jan Östlund
Conference contribution
2016

Hybrid RANS-LES Simulation of Separated Nozzle Flow

Ragnar Larusson, Niklas Andersson, Jan Östlund
Conference contribution
2014

Modal Decomposition of Separated Nozzle Flow

Ragnar Larusson
Licentiate thesis
2014

Comparison of Eigenmode Extraction Techniques for Separated Nozzle Flows

Ragnar Larusson, Niklas Andersson, Lars-Erik Eriksson et al
Paper in proceedings
2014

Investigation of supersonic jet flow using modal decomposition

Ragnar Larusson, Haukur Hafsteinsson, Niklas Andersson et al
Paper in proceedings
2014

Investigation of a Separated Nozzle Flow with Transonic Resonance Using Dynamic Mode Decomposition

Ragnar Larusson, Niklas Andersson, Lars-Erik Eriksson et al
Report
2014

Investigation of Screech in Supersonic Jets Using Modal Decomposition

Ragnar Larusson, Haukur Hafsteinsson, Niklas Andersson et al
Journal of Logic and Computation, p. 25-28
Conference contribution
2013

Linear Stability Analysis Using the Arnoldi Eigenmode Extraction Technique Applied to Separated Nozzle Flow

Ragnar Larusson, Niklas Andersson, Lars-Erik Eriksson et al
Paper in proceedings
2012

Superiority of PANS compared to LES in predicting a rudimentary landing gear flow with affordable meshes

Sinisa Krajnovic, Ragnar Larusson, B. Basara
International Journal of Heat and Fluid Flow. Vol. 37, p. 109-122
Journal article
2012

Large eddy simulations of the flow around pyramids

Sinisa Krajnovic, Ragnar Larusson
Paper in proceedings
2011

PANS of Rudimentary Landing Gear

Sinisa Krajnovic, Ragnar Larusson, EYSTEINN HELGASON et al
6th AIAA Theoretical Fluid Mechanics Conference, Honolulu, 27 - 30 June 2011 (AIAA paper 2011-3109)
Paper in proceedings