PhD

As part of the Chair's research activities, 4 PhD theses have been completed or are in progress:

By Hanna SARA – PhD defense: September 20, 2017

Thermal management proved itself in improving the fuel efficiency of the engine. Nowadays, automotive companies tend to apply different strategies to answer the greenhouse severe laws. The PhD aim is to valorize and analyze the different thermal management strategies with numerical simulations over different driving cycles and ambient conditions.

A 1-D simulation code of the engine and its hydraulic circuits were built using GT-Suite. Four known driving cycles were chosen: NEDC, WLTC, AH and AU. In addition, an in-house developed driving cycle was introduced. An energy balance made over the different stages of the driving cycles underlines the importance of the heat storage and the exhaust heat recovery strategies.

Heat recovery was applied over the coolant and the oil at ambient temperatures of -7°C and 20°C. Hot coolant storage and hot oil storage led to improve the coolant and lubricant initial temperatures respectively. Different configurations (total of 7) were proposed and studied. A multifunctional oil sump was introduced. Important fuel consumption savings were obtained.


Exhaust heat recovery was then valorized. Heat exchanger was characterized over experimental setup then added to the engine model. Indirect and direct heating of the lubricant as well as both strategies back to back were tested. Remarkable friction reduction and fuel savings were obtained. Special configuration was proposed to control the lubricant high temperature instead of the bypass on the exhaust line. The study ended by valorizing minor strategies as the oil’s grade influence, the engine insulation, high temperature set point …

> For more information: See “Research Activities: Area 1- Thermal management”

 

By Vincent RAIMBAULT – in progress

By Mohamad YASSINE – in progress

By DEEPAK KUMAR - PhD Defense: February 13th, 2018

The exhaust emissions from automobiles are one of the major sources of air pollution in today’s world. Therefore, research and development is the key feature of the modern automotive industries to meet strict emission legislation. One of the key aspects to meet these requirements is to improve the gas exchange process within internal combustion engines. It is possible through design optimization of the air intake manifolds for internal combustion engines. One of such advancements in air intake manifolds is variable tumble systems (VTS). In VTS systems, tumble flaps are installed at the exit of the manifold runner in order to improve tumble ratio and hence air-fuel mixing. Another feature of the flow inside the intake manifolds is pressure pulsation effect. Therefore, the aim of the Ph.D. work is to simulate the pulsating air flow inside the air intake manifolds and to identify the effect of the pressure pulsations on the active components like tumble flaps. The simulation work in the present thesis has been carried out on open source CFD code OpenFOAM.

In a first step, the effect of pressure pulsations is simulated inside a steel tube and a simulation methodology is developed. The results of the simulation are validated on a specific experimental device, the dynamic flow bench. Then, simulations have been carried out on the main intake manifold with tumble flaps. Firstly, the simulations are performed with five different opening positions of the tumble flap in a steady state configuration. The forces and moments acting on the flap in steady state are obtained and analyzed. Then, unsteady simulations with pressure pulsation effects are performed. The results of obtained from unsteady simulation are compared with the experimental results in terms of relative pressure fluctuations. The effect of the pressure pulsation on the aerodynamic forces and moments acting on the tumble flaps are analyzed and explained.