Recently  I have become curious about simulation software other than CFD for geometrically complex problems or software designed to deal specifically with detailed chemistry. Working with automotive groups made me take a closer look at GT-Power Suite from Gamma Technologies and WAVE from Ricardo Software. The two software tools are direct competitors and are widely used in the automotive industry.

I wanted to know, quite simply, which software is better for simulating reactive flow processes, such as combustion or after-treatment processes in an engine? In order to answer those questions, I first needed to define what “better” means. So, I put together a list of systematic questions that a software customer would have to ask before purchasing simulation tools for his/her simulation. Then I spoke with both companies and studied their product literature (flushing out most of the marketing fluff) to answer those questions.

Incidentally, since when did marketing become defined as “make the purpose of the tool as incomprehensible as possible, by covering up what it can do by a bunch of fluffy middle-management-sounding words that make no sense in a sentence”? Does wrapping up all that technical complexity in a cloud of nonsensical marketing speak really help close software sales? Somehow I doubt it. But that’s a topic for another post.

So, which software should you chose for your next engine design/optimization project?

DISCLAIMER: please keep in mind that the interest of this blog is specifically in the area of reactive flows, so you probably would have a number of other questions to ask the vendors, before deciding on the tool.

First some background on the two software companies.

Gamma Technologies, Inc (GTI) develops and commercially licenses the GT-Power and GT-SUITE software tools. It is interesting that the company was started in 1994 by an ex-Ricardo employee. It is dedicated “to building the most advanced engine and vehicle simulation tools” and “to provide major productivity improvements for our customers through carefully designed software solutions.” Currently, they have over 300 customers which include Siemens, John Deere and Nissan Europe. Their U.S. office is located in Westmont, IL.

Ricardo Company is a publicly traded company with the main location in West Sussex, UK and WAVE sales office in Burr Ridge, IL. The company founder, Sir Henry Ricardo (born in 1885) has been designing and researching engines since early 1900. (I actually did not realize that the history of this company reached back that far. You learn something new everyday). The company is dedicated to providing “technology, product innovation, engineering solutions and strategic consulting to the world’s automotive, transport and energy industries.”

Ricardo has a large consulting arm where as Gamma Technologies is focused more on their software business. Since both codes are commercially supported and developed, both companies provide training courses, examples and manuals.

What is the basic purpose of the software tool?

Both tools are designed to simulate the whole engine system from the intake to tail pipe exhaust. These types of simulations can not handle the details of geometric and turbulent flow in the way that CFD can, which allows users to run large numbers of simulations of the entire engine, very quickly.

Since these simulations also do not involve detailed chemistry (100+ reactions) calculations, they allow the user to run many engine cycle iterations with varying conditions for the entire engine from intake to exhaust. Both codes claim to handle such applications as engine optimization - prediction and optimization of the complete engine from intake to tailpipe, combustion and emissions, thermal analysis – prediction of combustion chamber and exhaust component temperatures.

Here is example of how these tools might be used, according to one company representative: a car engine manufacturer might have a 160 hp engine and the development team needs to figure out how to make it into a 180 hp engine. They can set up the whole system in GT-Power or WAVE and see how air/fuel ratios, engine geometry, air intake, and compression ration can be varied in order to increase engine power.

Some Basics

GT-Power:

Simulation type: 1D, steady state and transient

Industries: engine and vehicle makers and their suppliers, ship and power-generation engine manufacturers, small 2 and 4 stroke engines and racing engine manufacturers.

Couples with: GT-SUITE, STAR-CD, Fluent, Chemkin (Gamma representative was not aware of anyone using that coupling), Simulink, and MS/EXCEL.

WAVE:

Simulation type: 1D, steady state and transient

Some included sub- models: diesel and SI Wiebe combustion models, SI turbulent flame propagation, engine-out emission, knock prediction, library of fuels and custom fuel generator

Industries: Passenger car, motorcycle, truck, locomotive, motor sport, marine and power generation industries.

Integration: STAR-CD, Fluent, Chemkin and DARS for chemical kinetic modeling

What are some outputs (predictions) that can I get with the tool?

Both GT-Power WAVE: power, torque, CO, NOx emissions, acoustic emissions, temperatures air/fuel requirements at different speeds and throttles, temperatures for manifolds, velocity of gas at the tailpipe and intake snorkel. (I am curious about how both claim to give decent predictions for emission species without running detailed chemistry calculations…more on that later)

What input is required from me as the user to the software?

Some of the inputs to both GT-Power and WAVE: Pipe diameters and lengths, compression ration, fuel injection rates fuel ratios spark timing, combustion data, properties of the fuel, cross sectional areas, lengths, boundary conditions, inlet pressures, wall temperatures, details of the fuel, injector profile, time when does combustion starts

What are some of the assumptions involved in running the software?

These are the answers that company reps gave me, when I asked them this question. As you can see, they are extremely limited. Of course none of the marketing materials provided this information. In my opinion sales reps could have easily had a canned answer for such basic question as “what types of assumptions are made in your software?” Instead I got this:

GT-Power: the flow is 1-D, turbulence modeling is non-existent in the pipes, there are some limited turbulence models in the cylinder, heat transfer model assumptions, “obviously there are a lot of other assumptions”

WAVE: no turbulence modeling at all, flow is 1-D, there are many assumptions

What are the typical run times for a single simulation?

Ricardo rep told me that typically WAVE is much faster than GT-Power for certain large runs.

Being interested in reaction flows, can the simulation accurately predict major and minor species inside the engine, throughout the combustion process? If yes, is there a limit on how many species or reactions?

GT-Power: GT-Power claims to be able to simulate NOx, CO and soot predictions using built-in empirical models. According to the GTI company representative, there is no limit to the number of species imposed by the software it self, however GT-Power users tend to stick with reduced, global chemistry (less then 20 reactions).

WAVE: No chemistry solver in the software itself. There is a user-programming option that allows users to couple WAVE to the Chemkin solver. The sales rep was not aware of anyone actually using this option at the time. They do have a customer in Europe that used WAVE coupled with DARS chemistry solver.

Yet both programs claim to be able to predict exhaust species. When I asked GTI rep if those predictions were simply qualitative results or trends, he told me that no, customers actually get quantitative results for emission species from GT-power while using reduced mechanisms. Now I am just a simple kineticist, but how do you get accurate predictions of products of a complex combustion process without actually solving for the underlying detailed chemistry (by detailed chemistry, I mean thousands of reactions)?

It is a real pain to reduce a ten thousand reaction mechanism down to twenty steps, and the resulting mechanism only works in an extremely narrow filed of parameters (move out of that narrow pressure/temperature/compression-ratio range and the reduced mechanism is no longer valid). I am not sure that I really believe that either GT-Power or WAVE can predict emissions or soot in a quantitative fashion. But then again, I only spent five years conducting thesis work on that stuff…

Commercial price for a single seat?

Both companies asked that interested users contact them for a price quote, but I was told by one of the representatives that the pricing is very similar for GT-Power and WAVE.

Verdict

I spoke with the sales reps for both companies and I have to say that they were surprisingly reluctant to tell me why their software is better than their direct competitor’s. Both were very quick to admit that GT-Power and WAVE are very similar, but both were rather hesitant to describe what exactly made them different. Which makes me think that they are either not sure of what their competitive advantage is or for some reason they do not feel like sharing that competitive advantage with the rest of the world.

Both tools are very similar in their applications and uses. According to the GTI representative “GT-Power is newer and has more features than WAVE”. According to Ricardo rep, WAVE is a lot faster for large simulations and its acoustic simulations are vastly superior to GT-Power since that is where the company has focused their latest development efforts.

GT-Power claims to have an internal chemistry solver but their customers have only used it with very reduced (less then 20 reactions) mechanisms. WAVE can couple with Chemkin and DARS chemistry solvers, but that coupling is done with either user-programming as is the case with Chemkin solver, or it was done as a custom job for a customer as is the case with DARS solver.

My conclusion? If you are looking for a complete engine simulation that can run numerous iterations and you are not really looking for accurate predictions of emission species, WAVE or GT-Power might be the right tool for you. To find out more, put together a systematic list of questions, specific to your problem and don’t forget to include the basics (what are the user inputs, outputs and assumptions made with the software) and call up the company reps.

If you have had experience with either one of these software tools, please post a comment below. That information is very valuable to all of us in the computer modeling field.

Thanks for reading and Happy Modeling,

Masha

Vendor Contact info:

WAVE

Patrick C. Niven, Global Product Manager

Ricardo Software - Chicago Technical Center

7850 Grant Street

Burr Ridge, IL 60527

Direct Dial: (630) 468-8764

Telephone: (630) 789-0003

e-mail: Patrick.Niven@ricardo.com

www.ricardo.com

GT-Power

Gamma Technologies, Inc.

601 Oakmont Lane, Suite 220

Westmont, IL 60559, USA

Telephone: +1 (630) 325-5848

E-Mail: CAE@gtisoft.com

This entry was posted on Thursday, May 14th, 2009 at 12:16 pm and is filed under Software Review. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.