Saturday, 10 December 2016

The difference between NUMBERS and RATES

Was talking to No3 Son recently about a piece of science homework in which he had to chart and comment on 2012-2014 cancer statistics.

2012-2014 Cancer Data

The data was a great example of how the NUMBER of cases can give a very different picture to the RATE of cases. Below is what No3 Son wrote...

Cancer NUMBERS

The graph above has a “bell curve” shape, peaking at 60-79yrs and has a thin tail extending down to 0yr. The highest number of cancer cases,in the 70-79 year group, is 97670 and the lowest amount of cancer cases, in the 0-9 year group, is 1203. When people look they may think that 70-79 is where the biggest danger lies. This may be misleading as the graph shows the number of cases not the rate (e.g. per 100,000 people).

To obtain the rates I got the 2011 census data. Then I worked out the number of cases per 100,000 people. This is shown below and looking at the graph below it is clearly different and now you can see that the older you are the more chance you have of getting cancer.


Cancer RATES

Saturday, 26 November 2016

Citius, Altius, Fortius - Hervé Morvan's inaugural lecture

NSB was chuffed to find that the recent UoN Inaugural Lecture by Professor Hervé Morvan, Director of the Institute for Aerospace Technology and Head of Gas Turbine and Transmissions Research Centre has been posted onto YouTube. This post is based on the lecture, with some additional bloggage and linkage.

Prof Morvan began by explaining that the translation of the lecture title was the well known Olympic slogan "Faster, Higher, Stronger" before moving on to talk a little about Britany, the French region he grew up in. The Prof commented that he had a passion for comic books and illustrated novels and that, unlike fellow Gaul Obelix, he "doesn't need a potion to get energised".

Obelix and his Menhir

Prof Morvan started his UoN career applying Fluid Dynamics theory to hydraulic applications such as dams, water systems etc. An early collaborations with Donald Knight at Birmingham Uni on the "roughness" of river channels won the Schoemaker Award from the IAHR Hydraulics organisation. You can download the paper here and read more about this area of research at this UoN Page.

Rough flow...

...Smooth flow !

The Prof also worked on models of cataclysmic prehistoric floods in the Altai region of Siberia, where flows were in the region of 6-9million m3/sec, some 10,000 times as great as flows in a normal river. You can read the paper here.

Gigantic current ripples in Kuray Basin, Altai, Russia, as though a huge amount of fast moving water has flowed over this surface

Prof Morvan became involved with Rolls Royce around 2006, starting in hydraulics, then holding a RAEng industrial fellowship in 2008 before working at Rolls Royce for one day a week as a specialist until the responsibilities of the IAT and other efforts meant that Prof Morvan had to give up his Rolls Royce position.

Much of Prof Morvans work with Rolls Royce has been in the area of ensuring effective fluid cooling of the engine core, bearings and other areas. Computational Fluid Dynamics (CFD) models were important because should the fluid flow had dead spots, or did not reach certain areas, then there was a risk that these might overheat and fail.

To give a feeling for what a Rolls Royce Trent aeroengine has to deal with, Prof Morvan pointed out that a Rolls Royce Trent jet engine would typically take in 1.4 tonnnes of air per second.

The front fan sucks in the air, the turbine squeezes it, burns it then blows it out the back.
Turbines at the rear are spun by the exiting gas and power the fan and turbine at the front of the engine via the central shaft.

Alongside his Rolls Royce work, Prof Morvan became involved in a very different project in the lead up to the 2008 Olympics. This project involved helping Speedo to develop their LZR low-drag swim costumes and built on previous efforts started by the late aerospace engineer Barry Bixler, who became became interested in the subject when his daughter took up swimming. The costumes work use a number of techniques to reduce drag, including a foam layer that makes the swimmer more boyant and the use of elasticated panels that squeeze the body and reduce cross-section. The project involved analysing the swimming actions and shape of hundreds of swimmers, and then using CFD to see how the swimmers shape could be modified to reduce water resistance. More information can be found here, here, and here. Some of the Speedo patents are GB2444803 and GB2444804

Computer model of the Speedo LZR 

Looking at how technology has progressed, the Prof pointed out that fuel requirement per passenger was down some 70% since the days of the Comet, while engine noise has been reduced by some 70% in the same time period. The aero industry was not resting on its laurels, however, and has committed to significant further efficiency improvements, such as the roadmap by IATA and others to achieve a "50% reduction of the world air transport’s carbon footprint by 2050". These savings are hopefully going to be delivered by projects such as "Clean Sky 2" and "Horizon2020".

The Rolls-Royce composite carbon/titanium (CTi) fan blade under flight test as part of "Clean Sky"

A significant part of the talk gave an overview of how Prof Morvan and his team had spent several years researching fluid dynamics to improve their CFD models so that they do a better job of simulating the complex oil flow in engine areas such as bearing chambers. The challenge in this area is significant, as the model needs to replicate both thin films and pools of fluid, as well as how the oil interacts with high speed rotating machinery such as bearings.

You can read more about the (surprisingly long) history of fluid dynamics studies in this presentation by Andre Bakker. And there is an easy to understand comparison of computational and experimental fluid flow analysis techniques in this set of slides by Dmitri Kuzmin at Dortmund University.

Engine core cooling is vital, not least because the engine core is becoming more compact and the turbomachinery working at higher speeds and higher pressures and temperatures. The simulations Prof Morvan's team does are one step in the direction of right-first time digital design, which reduces the need for testing and shortens the design process, which is key to ensuring that Rolls Royce engines remain competitive. You can read one of Prof Morvan's latest papers, on the modelling of oil droplets in a bearing cage, here.

CFD simulation of two liquids with differing densities interacting

Prof Morvan then went on to talk about future developments, which he placed in two categories:

Firstly, there are future engine architectures, such as the Rolls Royce Ultrafan™ Engine, scheduled for introduction in 2025 (which means engine testing has to start in the next few years!). This is a geared design, which allows the bypass fan to operate at a different speed to the core. This, in turn, gives the core freedom to run smaller, faster, hotter and more efficiently. The engine aims to offer at least 25 per cent improvement in fuel burn and emissions against the current baseline. Prof Morvans team is using their transmission and modelling skills on this project.

Another engine architecture being considered is the "Open Rotor" concept (see also here), although this had a number of technical and certification issues to be overcome (in particular, how would a broken rotor be contained so that it did not hit the fuselage).

Geared fan in the forthcoming Ultrafan™

Rolls Royce Open Rotor design

The second area of future development related to the use of electric or part electric propulsion systems. Initial steps are being taken with the Airbus E-fan aircraft whose ducted fans are driven solely by battery power.

While E-fan has shown that electric flight is possible, it is not a revolutionary technology. Prof Morvan believes that the IAT has great ambition and capability for the next stages with its G2TRC and PEMC groups. Radical changes are likely with the progressive marriage of mechanical and electrical systems and a direction of travel towards all electric.

At present just a few percent of aerospace research effort is directed at electric propulsion but this is bound to grow ten fold and Prof Morvan's group intends to be a key player both nationally and internationally.

An Economist article describes how so-called "Distributed Electrical Power" architectures could dramatically change many aspects of aircraft design, efficiency and capability.

To see what is happening in the US, worth having a look a couple of NASA presentations (see here and here) - some remarkable stuff on the drawing board.

In Europe, Airbus and Rolls Royce are working on the "E-Thrust" project, which is a design study for a hybrid powered airliner.

With electrification, cooling remains a key concern (together with reliability), so the IAT expects to be contributing here also.

Airbus E-fan

Airbus E-Thrust hybrid airliner

NASA X46

Prof Morvan closed out the talk by commenting on forthcoming projects and the industrial infrastructure in the Midlands, commenting that:
"... the Midlands is doing very well, it's a good place [for centres like the ATI] and that is because universities are working with industry..."
The Prof commented that the region was the premier destination for CleanSky funding - with some 32milllion Euros coming into the area and added that the "Midlands Engine for Growth" was another positive factor in the areas favour.

These regional investments benefit not just the University of Nottingham, but also Loughborough, Warwick, Birmingham, Aston and Leicester Universities as well.

One nice touch that the Prof added to the talk was to randomly pop up images of famous aircraft and ask the audience, rhetorically, to identify them. These included the Dassault Super Etendard, legendary pilot Chuck Yeager, stills from "The Right Stuff" and the Mirage 2000 which Prof Morvan described as "the most beautiful aircraft, in my view, ever made".

The Right Stuff 

Prof Morvan has a blog at the University of Nottingham. In addition, you can read more about Prof Morvan's life and comments on industry in this rather nice interview. The following comments are taken from the interview and seem like a good way to close out this post:

"Make the most of any opportunity that is given to you. In a university, opportunities exist for initiative-takers, so go after things and make a difference; people will notice and you will go places. I have learnt from Rolls-Royce that as long as you deliver and can be trusted, your ideas can have a real future and make a difference.

Be flexible and adaptable, too. I wasn’t necessarily dead-set on solving a particular fluids problem when I arrived at Nottingham (I started on hydraulics in Civil Engineering!); I had fluid skills; I was very interested in aerospace; in energy and I made these skills available to the sectors, delivered for people, proved myself in the process I think and it has paid back. "


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Apollo Programme Manuals
Interview with Prof Farouk El-Baz
Smithsonian Air and Space Museum
Background to the Space Shuttle

Image Sources
Obelix, Instability, Rough River, Smooth River, Altai, LZR, Jet Engine, Blade, Ultrafan, Open Rotor, E-fan, The Right Stuff, X57