Effect Of The Engine Speed And Loading On The Heat Transfer Within Exhaust Valves

Abstract

The aim of the present paper is to investigate numerically the heat transfer within exhaust valves by considering the actual boundary conditions provided from an internal combustion engine at differentload and speed. For this purpose, the valve is subdivided into seven adequate subdivisions to better assess the effect of each engine parts, therefore, an average value of the transient heat transfer coefficient (HTC) and the adiabatic wall temperature (AWT) for each subdivisions are evaluated during one cycle. These two parameters are introduced as boundary condition in a FEM model. The simulations are done at diverse engine regime, and therefore, the trend of the real boundary condition in term of HTC and AWT are given versus engine speed at different load. The findings show that the HTC increases linearly with engine speed however, the AWT decrease slightly at partial load and increase in the case of full engine load. The obtained model is used to highlight the temperature map, which will certainly help to avoid any damage to the exhaust valve.

Thermo-mechanical stress analysis within a steel exhaust valve of an internal combustion engine

“…To cover this insufficiency, the present paper proposes to establish a FEM that considers the thermo-mechanical behaviour of an exhaust valve. It provides further results concerning the exhaust valve of the thermos-mechanical behaviour in the same exhaust valves studied by Cerdoun et al [14][15][16][17] Consequently, the main contribution of the present paper can be listed as follows:…”

“…In contrary to the work done by Cerdoun et al, [15][16][17][18] in which the average of the heat transfer coefficient and the adiabatic wall temperature are taken during one engine cycle. In the present work and in order to assess well the effect of each period of the engine cycle, the averaging is taken at two periods (a period when the valve is closed and a period when the valve is open).…”

“…To well identify and quantify the boundary condition surrounding the valves, the subdivision done by Cerdoun et al [14][15][16][17] is retained and completed by the mechanical load in which the different parameters that affect both mechanical and thermal loads on the valves can be assessed. This subdivision is based on the position of the exhaust valve in the engine block during the thermodynamic engine cycle.…”

“…The tribology at the seat and at the guide, the flow regime within the exhaust port and heat transfer at the seat of different valve lift was all considered by Cerdoun et al 15,16 They also concluded that, the boundary conditions implemented as an average of HTC and adiabatic wall temperature (AWT), underestimate the temperature, whereas cyclic boundary condition required more run time to reach a steady state. Recently, Cerdoun et al 17 focused on the heat transfer within exhaust valves by considering the actual boundary conditions provided by an internal combustion engine at different loads and speeds. The findings showed that the HTC increase linearly with engine speed.…”

“…However the AWT decrease slightly at partial load and increase in the case of full-engine load. All the works cited in references [14][15][16][17] used average boundary conditions over one engine cycle wish may underestimate or overestimate the boundary condition's real values.…”