University of Waterloo Internal Combustion Engines WAVE Engine Modeling Project

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User Generated

User

Gvz1998

Subject

Engineering

School

University of Waterloo

Description

Report Requirements

1. Please use SI Units

2. Justify your selection to the SOC. Include graphs comparing results of relevant parameters to justify your choice of the optimal SOC. Please note that there is no “exact” solution to this problem, there will be some leniency to the SOC (+/-2°).

3. Include graphs comparing the results between the varying engine speeds. (ie. Engine speed Vs. Torque, Engine Speed vs. Power, ect.) Look at the class resources to find examples of relevant graphs to include in the report.

4. Include results with analysis to document the effects of changing combustion duration

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Internal Combustion Engines W2021 Riccardo WAVE Lab Department of Mechanical, Automotive & Materials Engineering 1 Agenda ➢ Assignment Overview ➢ Assignment Overview ➢ Riccardo WAVE ➢ Ricardo WAVE ➢ Specific Assignment Goals ➢ Specific Assignment Goals 2 Assignment Overview ➢ Using Riccardo WAVE 1-D engine simulation software you will be required to evaluate the performance of a single cylinder 4-stroke engine ➢ Following the report requirements as detailed in document on blackboard, students are required to evaluate the engine performance and optimize across a range of engine speeds ➢ Assignment Overview ➢ Ricardo WAVE ➢ Specific Assignment Goals ➢ Generate an engineering report on the results from the simulation. ➢ Length of report should be between 5-10 pages 3 Ricardo WAVE - Access ➢ Assignment Overview ➢ Ricardo WAVE ➢ Specific Assignment Goals 4 Ricardo WAVE How does Ricardo WAVE Work? ➢ Assignment Overview ➢ 1-D Simulation → Only considers the effects on medium with respect to time and one coordinate dimension (transient solution) ➢ Ricardo WAVE ➢ Specific Assignment Goals V1 P1 T1 V1 ….. • • L V2 P2 T2 V2 ….. Given characteristics about pipe can be roughness, wall temperature, heat transfer coefficient, ect. you can calculate output pressure, temperature and velocity Think back to fluids, heat transfer and thermodynamics. Ricardo WAVE is a solver that links the concepts described in these classes 5 Ricardo WAVE • 1-D equations are solved for each of the components. Equations are discretized to be solved. All mass and energy must be conserved for the whole system • Despite the simplicity of solving for a single component (ex.pipe flow), these equations can get quite complex. Any component can be solving a number of equations simultaneously to obtain accurate results ➢ Assignment Overview ➢ Ricardo WAVE ➢ Specific Assignment Goals 6 Ricardo WAVE – Combustion Model • Combustion can be modeled in a number of ways, however for this project we will be using the simplest combustion model, the Wiebe (Vibe) Model 𝑥𝑏 𝜃 = 1 − exp −𝑎 𝜃 − 𝜃0 ∆𝜃 𝑎 is the shaping parameter; a=5 𝑚 is the form factor, m = 2 𝜃0 is the start of combustion ∆𝜃 is the duration of combustion 𝜃 is the crank angle • • 𝑚+1 ➢ Assignment Overview ➢ Ricardo WAVE ➢ Specific Assignment Goals Wiebe Function Gives good agreement with experimental data (realistic mass fraction burned) This is NOT a predictive combustion model! 7 Assignment Goals • You will evaluate a single cylinder engine to find the optimal start of combustion with a given Wiebe function (set heat release curve) • Effects of changing engine speeds on engine performance • Effects of changing combustion duration on engine performance • Understand simple engine models, understanding of its uses and its limitations ➢ Assignment Overview ➢ Ricardo WAVE ➢ Assignment Goals 8
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Tags: constant speed engine parameters Four Stroke Engine Procedure Instructions Selecting the Ideal SOC

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Explanation & Answer

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RICARDO WAVE ENGINE MODELLING PROJECT

Name
Institutional Affiliation
Professor’s Name
Date

Contents
INTRODUCTION .......................................................................................................................... 3
Four-Stroke Engine. ................................................................................................................ 3
Background ..................................................................................................................................... 4
DESIGN OF THE MODEL AND DATA ...................................................................................... 6
Design ......................................................................................................................................... 6
Engine Parameters .................................................................................................................. 6
Procedure Instructions ................................................................................................................ 6
Selecting the Ideal SOC .......................................................................................................... 7
ANALYSIS ..................................................................................................................................... 8
Justification for the SOC Choice ................................................................................................ 8
Performance ................................................................................................................................ 9
Varying the Combustion duration at a constant speed ..................................................... 9
Question: For the varying combustion duration explain the performance gets worse at
extremely short durations. Is this a realistic scenario? ................................................... 10
Question: .............................................................................................................................. 10
To determine the best performance has been reached under a constant combustion rate, the test
for varying speeds was conducted. As later discussed at a given engine speed and SOC the
performance becomes constant before it starts to drop. ............................................................ 10
Varying the Speed ............................................................................................................... 11
Question: What are some limitations of the 1D model? What would be the limitations
of using a 1D model like this when comparing to real engine results? .......................... 12
CONCLUSION .....................................................................................................................