Assessed Coursework Submission

Module U04589 Module Motorsport Engine Technology

Assignment title/No

Coursework 1 Due date:

28/11/2014

Estimated total time spent on 48 Hours

If this is a group assignment, please enter all group members’ numbers, names, andif relevant, group number or name.

StudentNo(s):

Student Name(s):

12019421 Jack Hordley Group: N/A

Statement of Compliance (please tick to indicate that all elements are included)

I/We have enclosed all the required elements of the coursework submission

I/We have attached a completed copy of the relevant mark-scheme for this assignment, showing the overall mark I/we believe this work deserves

I/We declare that the work submitted is my/our own and that the work I/we submit is fully in accordance with the University regulations regarding assessments (www.brookes.ac.uk/uniregulations/current)

Student Signature(s):Date:

FOR SCHOOL USE ONLY

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Notes.

Module U04589 - Motorsport Engine Technology

Course-work 1: Engine test-rig measurements, combustion and performance analysis

Module No. and Name : U04589 Motorsport Engine

Technology

Student Number : 12019421

Student Name : Jack Hordley

Lab Session and Date : Week 4 & Week 8

Report Submission date : 28/11/2014

Total Number of Words(excludes captions, and

: 890

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tables)

Mark Scored :

Module Leader: Dr Fabrizio BonatestaRoom R1.05Email: fbonatesta@brookes.ac.uk

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1.0 Introduction

This assignment will look at the working principles and

performance parameters of an internal combustion Si engine.

The engine investigated is a 1.6 Litre Direct injection with

turbocharger and intercooling. This is coupled to a Visio

Schenck eddy dyno to give brake work reading. Sensor include

an optical crank sensor to give engine position, pressure

sensor in cylinder, inlet and exhaust. Thermo coupling sensors

to give air temperatures and fuel meter (400cc capacity) to

give specific fuel consumption. 9 operating condition will be

surveyed with varying load and speed (60, 90 & 120 NM load @

1600, 2300 & 3000 RPM). The data will be analysed and graphs

produced to understand how combustion process and engine

performance varies.

2.0 Methodology

The engine data will be processed in excel to provide graphs

of varying parameters to compare engine indicated and brake

performance under different operating conditions. Cylinder

pressures are given as gauge rather than absolute so need to

be converted. The inlet pressures are absolute so these can be

used to reference the cylinder pressures to give absolute. The

trace of Cylinder pressure vs CA where the line remains flat

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before rising is said to be about equal to the mean inlet

pressure. For 1600rpm @ 60N/M AVG Inlet = 0.632767361 and AVG

Pressure from 150-180 CA = -0.398330645. So 0.632767361- -

0.398330645 = 1.0311 Bar.

3.0 Results and Discussion

P(Ѳ) Varied load at fixed engine speed

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As can be seen from the graphs, peak cylinder pressure occurs

later in the cycle as load increases, this is likely due to

the denser A/F mixture requiring less ignition advance. Also

peak pressure in cylinder increases with load as the cylinder

is more efficiently filled. At 2300 RPM peak pressure is

greatest at 90NM load. It’s possible that air velocity is kept

higher at this speed when the throttle is open less, so

filling the cylinder more efficiently. This combined with

later ignition gives a higher cylinder pressure.

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P(Ѳ) Varied speed at fixed load

With load fixed, greater cylinder pressure is achieved at

lower RPM where there is more time for the cylinder to be

filled effectively and spark timing can be reduced closer to

TDC. However at 60NM load the highest pressure is achieved at

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2300RPM, this could be a function of camshaft timing providing

better cylinder filling at this speed.

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P(V) Fixed speed Varied load

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From the graphs it can be seen that at higher load the

positive work (upper loop) is greater and the lower loop

containing pumping losses is reduced. Pumping loop mainly

above atmospheric pressure due to turbocharger.

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P(V) Fixed load varied speed

At fixed engine load, reduced RPM gives the greatest positive

work area. The pumping losses (lower loop) vary less with document.docx Page 11

engine speed than with load as the throttle position variance

is less. Time losses are also reduced at low RPM so more

positive work can occur just after TDC.

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Heat release per crank angle (fixed speed)

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At low load more work is produced before TDC (0 degrees) as

ignition has to take place sooner for the lower density charge

to ignite. At high load ignition occurs later in the cycle so

more heat is released on the power stroke, also the denser

charge has a higher energy content so produces more heat.

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Heat release per crank angle (fixed load)

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At fixed load, peak heat release is highest at low RPM where

ignition time losses are less and time for heat transfer to

take place when the piston is near the top of its stroke

longer. Traces begin to reduce when the flame terminates at

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the cylinder wall and heat is lost to the coolant rather than

transferred as positive work to the piston.

Brake vs Indicated Quantities

Power increases with load and engine speed. Brake power is

less than the indicated power as it does not contain

frictional losses.

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Mean effective pressure traces remain consistent with one

another at 60 and 90 NM load where pressure is greatest at

2300 RPM. However at 120NM brake pressure is greatest at 3000

RPM and not 1600 RPM.

SFC traces remain similar with 2300 RPM being the most fuel

efficient speed with varied load. As with the indicated values

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the engine uses less fuel per unit of energy at 3000 RPM than

at 1600 RPM for both 60 and 90 NM load.

Greatest thermal efficiency is achieved at 2300RPM for both

brake and indicated. Thermal efficiency drops off at low load

where pumping losses are increased but friction remains the

same. The brake thermal efficiency does not drop off at the

same rate as the indicated quantities at 120NM load but they

do follow the same trend as efficiency becomes greater at

1600RPM than it does at 3000RPM.

The mechanical efficiency was calculated by dividing Wb/Wi. As

the brake work includes all losses and indicated work includes

time and pumping losses, subtracting Wb from Wi should give

the net frictional loss of the engine. The graph above shows

friction reducing with speed which cannot be correct as

friction should increase with engine speed.

4.0 Conclusionsdocument.docx Page 19

Overall the indicated quantities were very similar to the

brake quantities. Inaccuracies in the combustion data will

come from the fact that the value for gamma was assumed to be

constant. This value would actually vary with combustion

temperature. From analysing the results is can be seen that

the greatest gains in performance and efficiency are to be had

by reducing the pumping losses and time losses in the PV

diagram as frictional losses are minimal.

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5.0 References

Collin R.Ferguson & Allan T.Kirkpatrick (2001). Internal Combustion Engines. United kingdom: John Wiley & Sons. 6-14 & 39-53.

E M Goodger (1977). Combustion Calcultions. Surrey: The Macmillan Press LTD. 44-55 & 71-77.

John B. Heywood (1988). Internal Combustion Engine Fundamentals. Ney York: McGraw-Hill Book Company. 508-514.

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6.0 Coursework 1 - SELF ASSESSMENT

U04589, Motorsport Engine TechnologyCoursework 1 - Assessment SchemeStudent Name and Number: Jack Hordley 12019421

1. Critical analysis/discussion of the results – weight: 35%

Excellent

(8.75)(6.55)

(4.35)

(2.15)

Poor

(0.0)

Description of the engine-rig instrumentation and review of theoperating conditions investigated

X

Critical assessment/discussion ofexperimental data and results:

Combustion analysis x

Performance analysis x

Conclusions x

Total score % for part 1 30.6

2. Analytical methods and numerical results – weight: 45%

Excellent

(11.25)

(8.45)

(5.7)

(2.8)

Poor

(0.0)

Description of the analytical methods

x

Results on combustion analysis:P(θ) P(V) dQ/dθ (θ), etc…

x

Results on performance analysis:Wi imep (ηt)i ISFC, etc… x

Wb bmep (ηt)b BSFC ηm, etc… xTotal score % for part 2 36.6

3. Overall quality of the report – weight: 20%

Excellent(5)

(3.75)

(2.5)

(1.25)

Poor

(0.0)

Structure of the report xLiteracy accuracy and use of x

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referencesQuality of language/expression xQuality of visual aids (plots, figures and tables)

x

Total score % for part 3 16.25Total Mark % 83.45%

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