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Monday Post -- 04/05/2020

On a weekly bases, we found more and more interesting CFD/FEA topics. This week we found very interesting blogs and articles on many topics:

SRS as Part 0f Daily Engineering Routine - by Tom

Two main reasons for using SRS models should generally be mentioned. The first is for applications of which additional information that cannot be obtained from the RANS simulation is needed such as aeroacoustics applications where turbulence generated noise that can’t be extracted from RANS simulations with sufficient accuracy, material failure applications governed by unsteady mixing zones of flow streams at different temperatures depending on unsteady heat loading, applications regarding vortex cavitation caused by unsteady turbulence pressure fields, calculation of helicopter loads which are strongly dependent on the vortices generated by the tip of the rotor and alike. SRS might be mandatory in such situations even in cases where the RANS model can indeed compute the correct time-averaged flow field. Link for the detailed blog.


AI for CFD: Intro (part 1)

A very interesting intro to a story where describing my company’s efforts and progress in bringing AI (Artificial Intelligence) to the world of CFD (Computational Fluid Dynamics). We believe it will be a complete game-changer for many industries, not only bringing speedup and cutting TCO (Total Cost of Ownership) but most importantly, offering entirely new possibilities for the CFD users. These 3 elements are also the goals for us as a company, and I will be referring to them in my subsequent stories while sharing the progress of this fascinating research project at byteLAKE. Follow the byteLAKE website for recent updates.

Also, read more about AI for CFD by Marcin Rojek


Vertical Wiper Blades Reduce Aircraft Drag - CFD Reviews

Understanding of aviation aerodynamics advanced, research indicated placing the wipers vertically when not in use could improve aerodynamic efficiency and optimize fuel use.

Commercial airliners first demonstrated the concept on the McDonnell Douglas MD-11, a jet airliner primarily used by the cargo industry, proving that retro-fitting the blades vertically could decrease costly drag by 1.2%. As part of the effort to increase the capability of legacy aircraft, the Advanced Power and Technology Office, or APTO, part of the Air Force Research Laboratory, identified the KC-135 as a candidate for the modification in 2019, citing its horizontal wiper design and significant fuel use. According to 2019 data from the Air Force Total Ownership Cost database, the KC-135 fleet consumed over 260 million gallons last year, accounting for almost 14% of total Air Force aviation fuel use. “We’re partnering with the Southwest Research Institute, the Air National Guard and the Air Force Operational Energy office to validate the concept and determine actual efficiency gains,” said Ed Clark, APTO aviation program lead overseeing the initiative.

The team of researchers and aeronautical engineers employed a KC-135 from Rickenbacker Air National Guard Base in Ohio for comprehensive ground testing on the airframe. Using computational fluid dynamics, or CFD, they were able to model how air flows over the nose and windshield of the aircraft during flight, simulating both vertical and horizontal wiper positions. The CFD models enabled the Rickenbacker team to visualize areas on the airframe that produce higher drag, (shown in red in the photo posted along with this story) and identify potential efficiencies. According to the report, data showed a reduction in drag of 0.8% for re-positioning the blade vertically, and 0.2% for the slimmer wiper design.


DarkAero 1 and SimScale: Evaluating Wing Stall Characteristics -by SimScale:

The team at DarkAero used CFD through SimScale to virtually “fly” the wing of the DarkAero 1 at a range of different angles of attack to determine the angle of maximum lift and where stall occurs. Once the angle of a maximum lift was determined, the Karls further refined their simulation in the region a few degrees before and after stall, in order to then predict how the stall would develop on the wing. 

From the early design stage, the wing of the DarkAero 1 was designed to have a progressive stall that initiates at the root of the wing, progressing outboard towards the wingtips. Through analyzing simulation results from SimScale, they were able to design the DarkAero 1 wing so that it stalled effectively as planned. In the video below, Ryley Karl explains how SimScale was used to evaluate the lift coefficient and stall behaviour for DarkAero 1. 

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