Turbocharged Engineering

A little town called Maranello...

2009-02-26T17:07:00.003+01:00

After a recent business trip to Italy, I decided to spend an additional day in the Bologna area before flying back to Germany. My only real goal for the day was to spend as much time in Maranello as possible before heading back to the airport. After sleeping in for a few hours to gain back some much needed rest, I set off west from the center of Bologna. As fate would have it, I missed the turnoff for the Autostrada to Modena (the quickest route) but immediately saw road signs for Maranello, among many other small towns. I may have added 30 or 40 minutes to my trip by taking "back roads" but it was well worth it and I'd recommend this route to anyone. I've traveled to countless places around Europe over the past year or so, and this particular region of Italy is definitely high on the "most beautiful" list.

After passing through seven or eight little villages, I finally made it to Maranello. Everything here is dripping with Ferrari. It's as if the entire town is built around the Ferrari plant. Speaking of the factory, it's a exclusive deal to get a tour and unfortunately I had to settle for just the Ferrari Gallery. Hard to call it settling, really:

The Allard J2X

2008-10-09T22:15:00.006+02:00

One of my favorite race cars of all time is the Allard J2X. While it was never successful in any of it's races, it was years beyond the competition in terms of aerodynamic design. Despite the fact that the J2X was capable of far superior levels of downforce compared to rival offerings at Porsche, Peugeot, and Jaguar, a massively underpowered engine would ultimately hamper overall performance. Developed in the early 1990s for the Group C World Sports Car championship, the J2X never saw much racing action. After the Group C Championship dissolved in 1993, the Allard was retired from professional racing forever.

You can read more about the Allard J2X here at Mulsanne's Corner.

I've wanted to model and examine the flow around the Allard for a few years now. I've finally managed to create a model that bears a slight resemblance in both shape and overall dimensions. Of note, I'll be using the latest version of CFdesign for my simulation. This is of particular interest due to the many very small edges in my Allard CAD model. The latest meshing technology in version 10 of CFdesign should make the simulation setup a piece of cake...

Visualizing Natural Convection

2008-08-02T19:11:00.003+02:00

To help show the effects of natural convection on fluid flow (buoyancy-driven flow), I've modeled a simple coffee mug with a spinner positioned directly above. The spinner is free to rotate about its axis and will begin to turn as vertical air velocity increases. I've assumed a heat generation of 300 Watts inside the fluid in the mug (water).

No need to get into the complexities of how microwaves work to heat things, I just want to see the effect of the hot mug on air flow, but if you must know: About Microwave Ovens

Fun with Formula Cars

2008-07-15T16:33:00.003+02:00

I've uploaded a few YouTube videos showing flow and pressure results around my simplified formula car... enjoy!

Particle Traces

Engine Intake and Radiator Flow

Pressure Profiles

Formula 1 CFD

2008-07-14T23:13:00.012+02:00

Formula 1 is without a doubt the pinnacle of motorsport aerodynamics. Between extensive usage of both wind tunnels and very high end computing platforms, teams are constantly trying to one-up each other in the quest for maximum performance. Modern F1 cars are anything but the pure, smooth, handsome machines from yesteryear. Shod with flip-ups, viking horns, barge boards, turning vanes, nose cone holes, and hundreds of other devices aimed to shape, direct, and optimize airflow, Formula 1 cars appear as if they could poke an eye out from 50 meters away. While cars from the '80s and '90s may be more visually pleasing to the eyes, advances in CFD allow modern vehicles to navigate a track as fast or faster with substantially less engine power.

Formula 1 - 1990

Formula 1 - 2008

Particularly in the last few years, all teams have been investing great sums of money in superior computers to perform their CFD needs faster and more accurately. Once the realm of dreams, some full car simulations consist of 50-100 million cells. Rumor has it that one team has experimented with simulations exceeding 1 billion cells. Naturally, this computing power comes at a price, but with teams like Renault investing approximately 50 million USD in their CFD solutions, anything seems possible...

While only a select few have access to a machine with such staggering computing power, smaller scale studies can allow engineers with average workstations to take a look into what makes an F1 car so fast.

Air Particle Traces

Side Profile View - Air Velocity

Pressure Profiles (Including Ground Plane)

Front Iso View of Pressure

Rear Iso View of Pressure

Aerodynamic Stall

2008-06-10T20:37:00.013+02:00

If you are somewhat familiar with basic aerodynamics, you've probably heard of the term "stall". Wikipedia, the ever-so-accurate online database of all knowledge, past and present, has some great information on stalls and how they relate to both air travel and jet engines.

The basic explanation of stall is when an airfoil loses it's ability to create lift due to an angle of attack that is too great. Check out the information below ... (at your own risk for you Wikipedia haters :) )

Flight Stall

Compressor Stall

I've put together a simple 2D wing profile to show what happens to the air flow around the wing as the angle of attack is increased slowly from 0 to 30 degrees. Air separation is clearly visible through looking at velocity over the wing, the reduction in negative pressure on the top of the wing clearly shows the loss of lift, and air turbulence helps to illustrate the onset of the separation zone. Enjoy...

A summary of the lift and drag forces versus angle of attack is shown below. The wing I created has a critical angle of about 14 degrees.

Introduction to Racecar Engineering - FSAE

2008-05-30T11:17:00.008+02:00

Formula SAE programs are like factories for churning out great engineers. For many young engineering students, FSAE is their first real world engineering experience where they must apply the things they've learned and work efficiently with team members. In addition to having their noses stuffed in books and their brains struggling to keep up with the information, they spend a year (sometimes two) constantly thinking about their design, their deadlines, bringing it all together and praying for success.

Fortunately, there is no real penalty for failure at the FSAE competitions, but frankly, I've never met an engineer who didn't thrive off of winning. It's heartbreaking to witness a team that has put in so much effort for such a long time compete well in all of the events, only to watch their car break down in the grueling endurance race, ruining all hopes for a top ten finish. On average, only 35-40% of teams are able to finish the 22 kilometer endurance event each year.

Lots of information here about the Formula Design series. As of this year, there are nine Formula competitions worldwide.

Helsinki Polytechnik '07

Virginia Tech '07

Cal Poly Pomona '07

University of Western Australia '07

TU Graz '07

Part of the competition involves several static events like a sales presentation and a design competition. Some sales presentation videos from Virginia Tech over the past few years...

2005

2006

2007

The Virtual DP1

2008-05-29T17:25:00.008+02:00

Full DP1 external aerodynamics simulation using CFdesign. Airstream of 100 MPH with a moving floor. Note how the uniform incoming flow waves are indistinguishable downstream. A low-pressure, turbulent wake region is clearly visible behind the car. The air passing over, under and around the car separates from the car surfaces in this region and tries to fill the void as quickly as possible. The result is a suction zone of tumbling, random flow that constitutes a considerable amount of overall vehicle drag.

DP1 Project

2008-05-26T13:34:00.009+02:00

A few years ago, I came across this guy's website and it truly amazed me. To say I'm jealous of what he has done in relatively short periods of time is an understatement...

DP Cars - Random Research, Inc.

I whole-heartedly recommend looking through the website, and in particular, the section about the DP1 (pictured above). This is a ground up design with a very unique take on a small club racer sports car. With a side-by-side cockpit/engine configuration, carbon-fiber chassis and body shell, and a power to weight ratio to make $200,000 factory super cars look slow on a track, the DP1 is truly something special.

Random Research was kind enough to provide me with the DP1 body shell CAD model and I'll will examine the design with CFD here shortly. Stay tuned...

Ferrari Ingenuity

2008-05-06T18:45:00.008+02:00

One of the perks of my job, besides the fact that it's intensely fun, challenging, and diverse, is that I get to play with CFD software every day. I'm always throwing random things at CFdesign to see how they tick, if you will. Sort of like a kid taking stuff apart and putting it back together. Except a lot cooler...

I'm a huge F1 fan and an active member of the F1Techincal forums over at http://www.f1technical.net/. Way back in August '07, a member by the name of Manchild came up with a nose cone idea here. The idea was to use a hole in the center of a Formula car nose cone to help use the nose cone itself to create additional downforce. Formula 1 cars, being so aerodynamically sensitive these days, can see massive benefits from even the slightest improvements. A differernce of 2/10ths of a second per lap could result in finishing 1st or 10th.

There was a lot of chatter about this idea over at F1Technical, and everyone had an opinion. It was one of the more exciting topics for months. Sure enough, in mid-April of '08, Ferrari introduced and eerily similar design into their nose cone., a full 7 months after Manchild had published his first drawings. A few images of the Ferrari nose cone:

I threw together a quick CAD model to see what this nose cone actually does. I think it looks pretty good considering I spent a maximum of 10 minutes creating it. Without seeing a really clear shot of the underside of the Ferrari nose cone, I can't really tell where the nose opening starts. I can see the leading edge of the rear most portion of the opening in the picture above, but not the front. I've taken a wild guess.

The numbers:

The new, holed nose cone produces approximately 7.3% less drag and 0.9% more downforce than the original, non-holed design. Not too shabby... In fact, it's huge. Real world results will undoubtablly vary, but my concept shows that the nose cone hole can have a big impact. Proper modelling of the rest of the car, wheels, barge boards, suspension components, etc. would be nice, but I think this simplified model tells a big story...

The standard nose cone results in a high pressure, stagnation zone directly underneath where the secondary wing element approaches the nose structure. The air piles up here and must divert either through the very thin gap between the wing and nose or turn to travel out and around the nose. No doubt this is a source of drag.

Top-side view of pressure on on the normal wing elements.

Bottom-side view of pressure on the normal wing elements.

Top-side view of pressure on the new nose cone wing surfaces.

Bottom-side view of pressure on the new nose cone wing surfaces.

Fast cars, driving suits, and a lot of luck

2008-05-06T13:51:00.003+02:00

I went to Virginia Tech for engineering after high school and after nearly failing out twice in my freshman year (I kid you not) I pulled it together, busted my rear, and finished school in four years. My senior year was dominated by my senior design project, Formula SAE. I can't be certain of this, but from all of the senior design projects I've seen over the years, nothing, and I mean NOTHING comes anywhere close the FSAE when it comes to preparing design engineers for the real world. I worked with a team of about 25 people to design, build, test, and race a small formula style car in less than 9 months. Designing something on your own is hard enough, but collaborating with 24+ other people, dealing with constant logistical issues and techincal problems, and coming together in the end to succeed at your goal is amazing. Especially for a young engineer. It was like a first job for me, and it taught me more about real world engineering than sitting in a classroom ever could.

My design area for FSAE was the engine intake manifold. I had some pretty lofty design goals before the year started...I remember drawing up all sorts of variable geometry intake manifolds similar to the designs used by BMW in their V8s at the time. Given the chance to do it all over again, I would have started simple and then simplified from there. The more complicated a design becomes, the more problems it brings. Add in the fact that 24+ other young "not quite engineers" were dealing with the same things, and the beauty of simplicity comes shining through.

I used CFD for my intake design, and it was anything but pretty. All universities have Fluent at their disposal, and after sitting down with a grad student over the course of several days, I learned how to open the program. If I told you Fluent was a bad tool, I'd be lying. I tend to overexaggerate things at times, but Fluent was really horrible for design engineering. The process went like this:

1. Create CAD model.
2. Export CAD model.
3. Import CAD model in Gambit.
4. Apply loads/mesh sizes.
5. Be frustrated.
6. Export mesh file.
7. Import mesh file into Fluent.
8. Hope everything is set up correctly.
9. Start simulation.
10. Wait for simulation to complete while watching numbers flash on the screen.
11. Attempt to interact with results after completion of the run.

It was borderline terrible. How can such a powerful program be so horrible to use? Maybe PhD level guys and gals enjoy pain and torture? Maybe they feel that there is no point in doing something if it isn't REALLY hard to do?

Fluent has it's place, it really does. It's just not on the desk of a mechanical engineer.

At some point near the end of the year, and aero engineering student approached me and showed me CFdesign. I was skeptical. The things he showed me were an order of magnitude more complicated than the stuff I had tested in Fluent, it took him 10 minutes to set it up, and he had results to look at right after hitting the go button. I could not believe it. This was well after my design phase when I saw the program for the first time. I was super anxious to throw my intake at CFdesign and see what it had to say about it.

This is where I apoligize to my fellow FSAE team members. I think we could have made a lot more power. CFdesign showed a few large issues with my design that Fluent didn't. I should say, CFdesign showed a few large issues with my design that I was unable to get Fluent to show me. As it turns out, I had used the wrong solvers, the wrong model setup, the wrong boundary conditions, the wrong turbulence mumbo jumbo...basically, everything I had done with Fluent was wrong. Now, this isn't to say that CFdesign couldn't have replicated the Fluent results, it's just that the combination of the default settings, super straightforward user interface, and general interactivity of CFdesign allowed me to set it all up correctly the first time. I was sold.

As luck would have it, my FSAE advisor, Dr. Kasarda, knew the small group of people who had created CFdesign. In fact, she went to school with them and was a close personal friend. After contacting the people at Blue Ridge, the makers of CFdesign, I drove up to Charlottesville from Blacksburg for an interview. It's the only job interview I've ever had.

A little about myself

2008-05-06T12:58:00.006+02:00

I'm a certified "gearhead". For as long as I can remember, I've been obsessed with cars, trains, planes, rockets, and pretty much anything else that goes ridiculously fast. It's not that I'm lazy (I am) it's just the thrill of going so much faster than is humanly possible.

I was born in Blacksburg, Virginia but only lived there for a few months. My family relocated to Salisbury, Maryland after my father changed jobs. We lived there for several years and when I was 5, we moved to Norrisville, a super small town, due north of Baltimore about two miles south of the MD/PA border. It was there that I "grew up". It was an awesome place to grow up, a little rural for most peoples standards, but we loved it. I have yet to meet anyone who comes close to the friends that I grew up with in Norrisville. Really solid people up there...

My parents thought there was something wrong with me when I was a child. Now, I cannot judge the validity of their early assessment, but my grandmother assured them that a young boy obsessed with the turning wheels of toys was perfectly normal. I think she's a smart woman. I can remember lusting after all sorts of cars from an early age on. It's funny to look back now and think about those cars I "loved". At the time, I guess I didn't know that a Geo Metro wasn't "cool". But a cool teacher at my elementary school drove one, so it was super cool to me.

As I got older and started reading books and investing massive sums in auto magazines, I gathered a pretty big wealth of (what some may consider worthless) data and specifications about all sorts of cars. The engine displacement of almost any modern supercar. The cylinder spacing of the Porsche 911 flat six engine. WHY the engine spacing is what it is in the Porsche flat six. We are talking suck the wind out of parties sort of information here. But, should I find myself in the company of one or more gearheads, rest assured, arbitrary numbers will be slung left and right. I don't know the exact number of car magazines I have accumulated over the years. My parents could give a more reasonable number since they are all sitting in their house in MD right now. I subscribed to Automobile, Road and Track, Car and Driver, and Motor-trend for about 9 years. 4 issues a month, 12 months in a year, 9 years. 432 issues, give or take 5 or 6. I'd say that any one magazine had about 50 pages of worthwhile reading, once you discount the advertisements. So there are about 21,600+ pages of automotive goodness sitting in my parents house right now. I've read all of them...but it didn't make me a genius. :)

I played a lot of sports in high school. I was never great in any single sport, but I could hold my own in all of them. I think the one true talent that I may or may not have is competitive auto racing. Not like country back roads stuff or drag racing, but true, circuit racing. The sort of stuff where your parents have to throw you into a shifter kart when you are 8 and then push you really hard until you are a professional racing driver at 18. I wouldn't have traded my childhood for all the F1 Championships in the world, but I think I could have done well in a fast car and a drivers suit....