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Assignment Cover Sheet
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In submitting this assignment, students should be aware of the following:
· Unless there are extenuating circumstances, work handed in after the hand-in date will receive a mark no greater than 40%; if handed in after the cut-off date (1 week after the hand-in date) the mark will be 0%.
· Student Handbook of Regulations: Section 5 covers procedures for students wishing to claim extenuating circumstances. Sections 4 and 6 define plagiarism and the procedures and penalties for dealing with it.
· You are advised to keep copies of all your assignments in case of difficulties.
Session 2016 – 17
Module Code: NHA2416
Module Title: Aerodynamics and CFD
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Assignment Component Number 1 1 out of total number of Assignment components
Assignment Title (where appropriate): Effect of cross wind on aerodynamics of ground vehicles.
Weight of this Assignment component for the module assessment: 25%
Module Outcomes Covered by this assignment as stated in Module Specifications document:
1 Knowledge and Understanding
On completion of this module, the learner will:
a) Understand the aerodynamic fundamentals affecting the forces acting on a vehicle in motion and the contribution of vehicle form towards the drag and lift coefficient and their L/D ratio.
b) Know the aerodynamic analytical, computational and experimental techniques to determine the drag and lift coefficients.
2 Abilities
On completion of this module, the learner will:
c) Be able to calculate the aerodynamic forces acting on a given vehicle and its components and their effect on vehicle performance.
d) Be able to apply CFD modelling to evaluate aerodynamic effects on vehicle body and its components
Hand out date of this Assignment component: 26/09/2016
Hand in date of this Assignment component: 19/01/2017
Assessment Criteria**:
1. Development of a computer model of a 10%
vehicle using CAD
2. Drag force evaluation 30%
3. Cross wind effect 30 %
4. Effect of domain length on prediction of drag force 20%
5. Validation of the results 10%
(** Please see the marking grid given at the end to clearly understand expectations)
Expected Time Requirement for this component of Assignment: 50 hours
Module Code: NMM 3552
Module Title: Vehicle Aerodynamics and Air Management
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Assignment Component Number out of total number of Assignment components
Assignment Title where appropriate: Effect of cross wind on aerodynamics of ground vehicles.
ASSIGNMENT BRIEF
Introduction
Understanding of aerodynamic and associated loads is very important in establishing the aerodynamic performance of a passenger car at high-speed and under crosswind conditions. This assignment aims to establish the effect of cross wind effects on car aerodynamics.
Specifications:
It is expected that students will develop a computer model of a passenger car of their own choice using CAD Package of their own choice. After developing the computer model students are expected to investigate the cross wind effects on car aerodynamics using commercial CFD package FLUENT.
1) Students are required to analyse the effect of vehicle speed on drag forces. The car speed is fixed at 40, 60 and 90 km/h without crosswind effects. Calculate drag, side and lift forces acting on the car as a function of speed. Plot drag, lift, side forces and a ratio of drag/lift force.
2) Investigate the response of the vehicle if flowing air approaches the vehicle at a 90 degree angle. Assuming crosswind speed at 5, 10, 20 m/s, compute drag, lift, side forces and a ratio of drag/lift. Plot all computed variables.
3) Investigate the effect of length of flow domain (take two different downstream lengths 1 x length of the vehicle and 10 x length of the vehicle) on the accuracy of results obtained. This analysis needs to be carried out at 90 km/h without crosswind
6) Validate with available data published in the literature.
7) Based on the investigations above propose conclude on the crosswind effects on driving stability.
The Report
The assignment report must have a formal structure and must include appropriate references (internet references may be included) and appendices. The maximum word limit for the report is 4000 words. This excludes the title page, headers/footers, list of figures/tables etc., summary page and the appendix. The report is to be word processed and an electronic copy must be submitted via turnitin.
Guidance
Higher grades will be associated with reports which:
§ Make effective use of information from a sufficiently broad range of appropriate sources e.g. available prototype, books, journals, technical literature and the internet. N.B. references should be seen as the evidence, which underpins the discussion and conclusions made in the report and not simply as sections to be copied.
§ Show understanding of the concepts used and explain any assumptions made in the analysis.
§ Follow a logical sequence and show in-depth analysis capability.
§ Include external features of the vehicle in the computer model.
§ Have a standard formal structure which makes good use of an appendix and make a clear distinction between references and bibliography. Have a tidy, standard approach to layout and presentation (one style rather than several ). Make good use of images and figures.
§ Are original and interesting in their discussion and in their ideas and conclusions.
Assessment Chart
Item |
Unsatisfactory |
Satisfactory |
Average |
Good |
Very good |
% |
0-20 |
20-40 |
40-60 |
60-80 |
80 and above |
Achieved |
1 |
2 |
3 |
4 |
5 |
Creation of geometry and Mesh 10% |
Inclusion of figure only |
1+ description of dimensions |
1-2+ justification of dimensions |
1-3+ justification of dimensions with steps in the creation model |
1-4+ justification of mesh used |
Drag force results 30% |
Inclusion only drag and lift forces |
1+description of boundary condition with simulation |
1-2+ Justification of boundary conditions |
1-3+ flow field analysis |
1-4+ establishing quantitative relationship among parameters of interest. |
Crosswind effect 30% |
Inclusion results with one crosswind speed only |
Inclusion results with all cross wind speeds
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1-2+Justification of boundary conditions |
1-3+ flow field analysis |
1-4 explanation of relationship among parameters of interest. |
Effect of domain length 20% |
Inclusion one domain length only
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Inclusion two domain lengths
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1-2+ forces computation |
1-3+comparison with results obtained from original flow domain |
1-4+ establishment of quantitative relationship among parameters of interest |
Validation 10 % |
Inclusion only numerical results |
1+inclusion of proposed validation strategy |
1-2+qualitative comparison with available data |
1-3+ quantitative comparison |
1-4+ error estimates |