OPTIMUM Power Technology:
Low Cost Combustion Analysis for University Engine
Design Programs
Using ICEview and NI Compact DAQ Chassis
World Headquarters (USA):
3117 Washington Pike
Bridgeville, A 15017-1496
USA
Tel: 412-257-9070
Fax: 412-257-9011
European Sales Office:
P. O. Box 6094, Stewkley
Leighton Buzzard LU7 0XW
United Kingdom
Tel: 44 (0) 1525 242130
Fax: 44 (0) 1525 242140
Japanese Office:
Fluent Asia Pacific Co., LTD
Nittochi Nishi Shinjuku Bldg. 18F,
Tokyo, 160-0023, JAPAN
Tel: 81-3-5324-7306
Fax: 81-3-5324-7302
URL: http://www.fluent.co.jp
Introduction
Analysis and measurement of in-cylinder pressure traces, or indicator diagrams, are long
established techniques, widely used in the development of internal combustion engines,
particularly within the automotive industry. This approach of assessing indicated engine
performance dates back to the earliest days of engine development and was used frequently by
Rudolph Diesel and others over 100 years ago. In fact, indicator diagrams were used as early as
1796, when John Southern, an assistant to James Watt, invented a method of creating indicator
diagrams on steam engines. In these early days, the measurements were simply used to
calculate the indicated performance or indicated mean effective pressure (IMEP).
In 1938, new techniques for pressure trace analysis were introduced by Rassweiler and Withrow
who developed a very effective technique for determining burn rate from measured pressure data
by estimating the apparent pressure rise due to combustion. This approach has now become the
industry standard for burn rate analysis, and is simply known as the Rassweiler and Withrow
method.
More recently, with powerful computing becoming widely available, there has been increasing
interest in this area with larger companies producing dedicated hardware and software packages.
Others have considered the use of more sophisticated techniques, by applying a full first law
analysis and even considering flame propagation, and many have investigated the various
aspects of processing, measurement accuracy and error analysis.
With the growing popularity of Formula SAE throughout the world, the need to gain a competitive
edge over other Universities has become even more important. OPTIMUM already offers an
FSAE version of its well respected Automated Design® for engine simulation, which is now in use
with over 50 universities world wide. While this is an invaluable tool in improving and optimizing
performance and helping students understand areas of gas dynamics, fluid dynamics and
thermodynamics, OPTIMUM has now enhanced its support of university and engine research
programs with the release of ICEview, advanced combustion analysis and high speed data
acquisition system.
Combustion analysis is generally regarded as technically demanding, sophisticated and very
expensive, beyond the budgets of universities, however it will always remain on the “wish list” of
many. OPTIMUM, working in conjunction with our partner National Instruments have developed a
solution that is PC based, intuitive, fast, accurate and most importantly of all, affordable for
university programs.
Background
OPTIMUM has a pedigree in advanced engine design and analysis tools. ICEview was developed
from our highly successful combustion analysis software known as PTrAn. This is a low cost suite
that processes data from high end combustion acquisition hardware. It is this expensive hardware
that prevented many universities from investigating how to improve the combustion
characteristics of their engines and hence overall
performance. This no longer the case. Using standard
National Instruments hardware platforms, many of which are
common place at universities, OPTIMUM have developed
ICEview as a low-cost, user-friendly combustion acquisition
package that incorporates PTrAn for fast and accurate postprocessing.
The system is PC-based and offers high-speed, crankangle-based sampling for all sensors allowing advanced
combustion analysis such as IMEP, burn rates and many
other combustion parameters. ICEview also performs knock
analysis and has many flexible digital filters to remove common but difficult to detect signals such
as aliasing. Powerful post processing of data and enhanced graphics allows information to be
visualized both clearly and concisely: cycle-to-cycle variability, cylinder-to-cylinder comparision,
statistical analysis and cross-correlation are just a few examples of how results may be displayed.
As stated earlier, it is Optimum’s intention to offer an affordable solution to combustion analysis.
Even if your university does not have the NI hardware required to run ICEview, large discounts
can be obtained from NI for educational establishments, try visiting their web site at www.ni.com
to see what huge savings can be made. Also visit Optimum Power Technology’s web site at
www.optimum-power.com to see the discounts we are offering to any FSAE team. And don’t
forget that all Optimum’s software is backed up by free technical advice and assistance on setting
up all hardware from our team of experienced engineers.
Optimum does not expect ICEview to be used
just for your university’s FSAE team, but we
actively encourage lecturers and professors to
build teaching modules around the software to
give students hands on experience in
combustion analysis, which will lead to a greater
understanding in the theory of combustion and
how different parameters this critical area of
engine design.
Also designed to work within the LabVIEW
environment, the NI graphical interface, ICEview
offers universities an ability to carry out
professional combustion analysis at a price that
will be within the means of all teams.
Equipment
A schematic of a typical set up is shown below. Piezoresistive pressure transducers are mounted
in the cylinder head and connected to the NI Compact DAQ via a charge amplifier. The encoder
is normally mounted directly onto the engine crankshaft and the output signals go straight into a
digital I/O module in the DAQ system..
NI Compact
DAQ
e
USB
Amplifier
Tran’d
Engine
Encoder
Figure 1. Schematic of a typical system
PC
The encoder provides the NI DAQ unit with the necessary pulses to acquire data on an angular
basis. Other than that, all that’s required is a PC to run ICEview. The typical NI hardware required
is reviewed below:
Chassis 9172
The NI CompactDAQ chassis comes with everything you need to connect C Series I/O modules
to your PC, including an AC power supply and a 6 ft USB cable. An NI CompactDAQ chassis
operates with as few as one C Series I/O module or as many as eight, so you can configure your
measurement system to meet your needs now and have slots left for future expansion.
Digital I/O Modules
National Instruments C Series modules for NI CompactDAQ work with multiple logic level types
and have multiple connector options for switches, encoders, and transducers.
The NI 9401 is an 8-channel, high-speed, bidirectional I/O module using 5 V/TTL logic. It can be
configured to have 8 inputs or 8 outputs or 4 inputs and 4 outputs. With an I/O delay time of only
100 ns, the 9401 is ideal for use with an angle encoder or to read or send trigger signals from/to
other equipment.
Analog Input Modules
National Instruments C Series analog input modules provide high-performance measurements for
a wide variety of signal types on the NI CompactDAQ and CompactRIO platforms. Each module
features built-in signal conditioning and direct signal connection via screw-terminal, BNC, D-Sub,
or RJ-50 connectors. Modules are available to accept signals from accelerometers, strain gages,
thermocouples or voltage sources.
The NI 9215 is a 4-channel module with simultaneous sampling up to 100 kS/s on each channel.
With a voltage range of ±10 V and 16-bit resolution, the 9401 is well suited to data acquisition for
combustion analysis.
System Review
Optimum Power have designed ICEview to be user friendly and intuitive. A new user can have
the system up and running in a surprisingly short time. Once the hardware is installed, only three
files need to be created before the collection of useful data can begin. These files are created in
a straightforward graphical interface.
The Engine File contains the engine details such as engine type, bore, stroke, con rod length,
compression ratio etc.
The Test File contains information on ambient conditions, sampling details (internal clock or
external encoder), and the level of software filtering to be applied.
The Trace File contains information on the method of pressure referencing, the encoder offset
relative to tdc, and the calibration of the transducers being used.
With these three files completed, the system is ready to go.
Optimum use National Instruments’ LabVIEW to collect the raw data in real time either on a time
basis or on an angle basis when using an encoder. The user can view the data in the ‘online’
mode or collect the data in the ‘record’ mode. Figure 2 shows a typical LabVIEW screen with two
cylinder pressure traces - one firing and one non-firing.
Figure 2
Once data collection is complete, the LabVIEW screen disappears and the ICEView screen
appears displaying the unconverted or raw data as shown in Figure 3. This particular data shows
the output of cylinder pressure transducers installed in a 45-degree V-twin engine.
Figure 3
The same data, now converted, is shown in Figure 4. The y-axis is now in pressure units (bar, in
this case) and both cylinder traces have been corrected for the encoder offset.
Figure 4
Once the user is satisfied that the data are correct, he can switch to PTrAn – the combustion
analysis package within ICEView.
Before calculating any of the combustion parameters, PTrAn checks the signals for signs of
thermal shock or drift in the pressure transducers. This alerts the user to any potential problems
with the test set up before proceeding with the analysis.
Figure 5 shows the default screen in PTrAn. The upper plot displays cylinder pressure vs. crank
angle while the lower plot shows Log P vs. Log V. The green lines represent the indices of
compression and expansion. The major combustion events, such as start of burn and end of
burn, are shown in blue on the plots. On the extreme right side of the screen are displayed 28
results calculated for this particular cycle. The user can use the spin buttons to move from trace
to trace and from cycle to cycle.
Figure 5
By right clicking in the plot area the user can change the plots to show other parameters derived
from the pressure data. Figure 6 shows the burn rate and mass fraction burned while Figure 7
shows the knock signature.
Figure 6
Figure 7
Summary
ICEView is a professional combustion analysis package, and through the university discount
system operated by both National Instruments and Optimum Power, offers the quality and
performance of similar systems but at a fraction of the cost. The software will give students the
opportunity to carryout combustion analysis to the highest level giving an excellent grounding and
understanding of exactly how to obtain optimum results.
The choice of Optimum to work in partnership with NI and their LabVIEW system gives
universities the possibility of using existing NI hardware, or purchasing low-cost general-purpose
hardware form NI. Due to its modular design, and the fact that the hardware is not specific to
ICEview, it can easily be used on other projects or in other areas of the department.
ICEView has been targeted at universities and priced at a level we believe to be well within
typical budgets. We believe that ICEView could easily be incorporated into teaching modules and
be used as a frame work for all automotive engineering students wishing to study combustion
analysis.
Buying ICEView will enhance your results and offer a great way to enter the technically
demanding area of combustion analysis at a very competitive price
For further information visit our web site at www.optimum-power.com or contact our offices at the
numbers given on the front page