Active Flow Control for Drag Reduction of Heavy Vehicles
Doktorsavhandling, 2012

This thesis considers the aerodynamics of trucks. The work focuses on the aerodynamic drag caused by the wake. Bluff-body flows are dominated by large dissipative vortex-shedding wakes with a low mean pressure compared to the high pressure on their frontal area. This induced pressure difference is the major contribution to the total aerodynamic drag. The flow separation at the aft of the trailer results in a large low pressure region that increases the pressure difference between the front and back. An effective way to decrease the size of the separation zone and increase the base pressure is to use active and passive flow control techniques (AFC and PFC). The objective of the present work is to apply active and passive flow control (AFC) strategies to reduce the typically large base pressure on bluff-bodies. The work is mainly based on numerical computations using large-eddy simulation of the turbulent flow on a simple semi-3D truckmodel. A thorough parameter study of a novel rear-end trailer geometry and the AFC parameters is carried out and an attempt is made to optimize the flap shape with AFC using Response Surface Methodology. The flow reattachment process, dynamics of the flow with and without AFC and corresponding wake structures are discussed. An experimental investigation of a typical synthetic-jet actuator is also carried out in order to evaluate the order of magnitude of the maximum possible momentum coefficient, Cμ. A semi-detailed 1/10th scale of a VOLVO cab with a trailer is experimentally and numerically evaluated with and without AFC. A full-scale road test employing AFC in a fullscale Volvo truck-trailer is also carried out.

Active and Passive Flow Control

Tilt-rotor wing

Large-eddySimulation

Heavy vehicles

optimization

Full-scale road test

Trucks

Bluff-body

Wake

Drag reduction

Aircrafts

Response surface methodology

Synthetic-jet Actuator

Virtual Development Laboratory
Opponent: Prof. Avraham Seifert

Författare

Mohammad El-Alti

Chalmers, Tillämpad mekanik, Strömningslära

Computations and full-scale tests of active flow control applied on a Volvo truck-trailer

Lecture Notes in Applied and Computational Mechanics,; (2010)p. 253-267

Konferensbidrag (offentliggjort, men ej förlagsutgivet)

Experimental and computational studies of active flow control on a model truck-trailer

EPJ Web of Conferences,; Vol. 25(2012)p. pp 16-

Paper i proceeding

Drag Reduction for Trucks by Active Flow Control of the Wake Behind the Trailer

Turbulence, Heat and Mass Transfer 6,; (2009)

Paper i proceeding

On the Download Alleviation for the XV-15 Wing by Active Flow Control Using Large-Eddy Simulation

ERCOFTAC WORKSHOP, Direct and Large-Eddy Simulation 7, Trieste - Italy, September 8-10, 2008,; (2008)

Paper i proceeding

Denna avhandling behandlar aerodynamiken av lastbilar. Extern flöde över lastbilar domineras av stora dissipativa virvelalstrande vakar med ett lågt medeltryck jämfört med högt tryck på sin främre del. Denna inducerade tryckskillnad är det största bidraget till den totala luftmotståndet. Flödet separerar vid baksidan av trailern och resulterar i ett stort lågtrycksområde som ökar tryckskillnaden mellan fram- och baksida. Ett effektivt sätt att minska storleken på separationszonen och öka bastrycket är att använda aktiva och passiva flödeskontroll metoder.

This thesis considers the aerodynamics of trucks. The work focuses on the aerodynamic drag caused by the wake. Bluff-body flows are dominated by large dissipative vortex-shedding wakes with a low mean pressure compared to the high pressure on their frontal area. This induced pressure difference is the major contribution to the total aerodynamic drag. The flow separation at the aft of the trailer results in a large low pressure region that increases the pressure difference between the front and back. An effective way to decrease the size of the separation zone and increase the base pressure is to use active and passive flow control techniques.

Drivkrafter

Hållbar utveckling

Innovation och entreprenörskap

Styrkeområden

Transport

Ämneskategorier

Strömningsmekanik och akustik

ISBN

978-91-7385-772-7

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3452

Virtual Development Laboratory

Opponent: Prof. Avraham Seifert