Fabien Harambat

Temperature and Heat Flux Behavior of Complex Flows in Car Underhood Compartment

In this work heat transfer and temperature behavior of complex flows encountered in the vehicle underhood compartment is experimentally studied and described with simple models. Underhood thermal measurements made on a passenger vehicle in a large-scale wind tunnel are reported here. The underhood is instrumented by 80 surface and air thermocouples and 20 fluxmeters. Measurements are carried out at three thermal functioning points, in all of which the engine is in operation and the front wheels are positioned on the test facility with power-absorption-controlled rollers. Models are proposed to predict the maximum temperatures and time constants of the underhood components as functions of the car speed and car engine power. The relative errors of the models are 3.6% and 3.7%, respectively. The maximum temperature and the time constant are crucial in the design and optimization of the underhood aerothermal management system. The results obtained in the present work also provide a large database for validation of numerical codes dealing with underhood cooling management.

A new method for simultaneous measurement of convective and radiative heat flux in car underhood applications

A new experimental technique is presented that allows simultaneous measurement of convective and radiative heat flux in the underhood. The goal is to devise an easily implemented and accurate experimental method for application in the vehicle underhood compartment. The new method is based on a technique for heat-flux measurement developed by the authors (Heat flow (flux) sensors for measurement of convection, conduction and radiation heat flow 27036-2,

A Quantitative Method for Assessment of Car Inclination Effects on Thermal Management of the Underhood Compartment

The study presented here concerns the impact of car inclination on the temperatures in the vehicle underhood compartment. We report here underhood thermal measurements carried out on a vehicle in wind tunnel S4 of Saint-Cyr, France. The underhood is instrumented by 80 surface and air thermocouples. Measurements are carried out for three different thermal charges (thermal functioning points). During tests, the engine is in operation, and the front wheels positioned on the test facility equipped with rollers, permitting the wheel power and rotational speed control. Three car inclinations are tested.

Parametric Analysis of Heat Exchanger Thermal Performance in Complex Geometries—Effect of Air Velocity and Water Flow Distributions

The thermal performance of automotive heat exchangers is greatly affected by the relationship that binds the nonuniformities in flow velocity and the distribution of upstream temperatures. Consequently, an in-house two-dimensional code is established to evaluate the thermal performance based on known parameters, namely, distribution of upstream velocity of an air–liquid heat exchanger, the flow rate of heat exchanger liquid, and the inlet air and liquid temperatures. A parametric research study is then performed to confirm the relation between the thermal performance of the heat exchanger and these different parameters. It was observed that nonuniformities in air velocity and water flow distributions decrease the thermal performance of a heat exchanger by up to 33 and 42%, respectively.

Drag reduction of a car model by linear genetic programming control

We investigate open- and closed-loop active control for aerodynamic drag reduction of a car model. Turbulent flow around a blunt-edged Ahmed body is examined at

Energy Management in Car Underhood Compartment—Temperature and Heat Flux Analysis of Car Inclination Effects

Re_{H}\approx 3\times 10^{5}

Characterization of MEMS Pulsed Micro-Jets with Large Nozzles

ReH≈3×105 based on body height. The actuation is performed with pulsed jets at all trailing edges (multiple inputs) combined with a Coanda deflection surface. The flow is monitored with 16 pressure sensors distributed at the rear side (multiple outputs). We apply a recently developed model-free control strategy building on genetic programming in Dracopoulos and Kent (Neural Comput Appl 6:214–228, 1997) and Gautier et al. (J Fluid Mech 770:424–441, 2015). The optimized control laws comprise periodic forcing, multi-frequency forcing and sensor-based feedback including also time-history information feedback and combinations thereof. Key enabler is linear genetic programming (LGP) as powerful regression technique for optimizing the multiple-input multiple-output control laws. The proposed LGP control can select the best open- or closed-loop control in an unsupervised manner. Approximately 33% base pressure recovery associated with 22% drag reduction is achieved in all considered classes of control laws. Intriguingly, the feedback actuation emulates periodic high-frequency forcing. In addition, the control identified automatically the only sensor which listens to high-frequency flow components with good signal to noise ratio. Our control strategy is, in principle, applicable to all multiple actuators and sensors experiments.

Aerodynamic performances of rounded fastback vehicle

The study presented here concerns the impact of car inclination on the temperatures in the vehicle underhood compartment. We report here underhood thermal measurements carried out on a vehicle in wind tunnel S4 of Saint-Cyr. The underhood is instrumented by 80 surface and air thermocouples. Measurements are carried out for three thermal functioning points: the engine in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. Three car inclinations are tested.© 2008 ASME