Characterization of the Inlet Port Flow under Steady-State Conditions Using PIV and POD

Abstract

Abstract:The current study demonstrates an experimental investigation of the tumble flow structures using Particle Image Velocimetry (PIV) under steady-state conditions considering the central vertical tumble plane. The experiments were carried out on a four-valve, pent-roof Gasoline Direct Injection (GDI) engine head at different valve lifts and with a pressure difference of 150 mmH 2 O across the intake valves. Furthermore, the Proper Orthogonal Decomposition (POD) analytical technique was applied to PIV-measured velocity vector maps to characterize the flow structures at various valve lifts, and hence the different rig tumble values. The results show that at low valve lifts (1 to 5 mm), 48.9 to 46.6% of the flow energy is concentrated in the large (mode 1) eddies with only 8.4 to 11.46% in mode 2 and 7.2 to 7.5 in mode 3. At high valve lifts, it can be clearly seen that some of the energy in the large eddies of mode 1 is transferred to the smaller flow structures of modes 2 and 3. This can be clearly seen at valve lift 10 mm where the values of the flow energy were 40.6%, 17.3%, and 8.0% for modes 1, 2, and 3, respectively.

On the Application of Proper Orthogonal Decomposition (POD) for In-Cylinder Flow Analysis

“…The POD code in previous paper [4] was employed here. The code mathematically minimizes the following:…”

“…The POD code in previous paper [4] was employed here. The code mathematically minimizes the following: quantifies the kinetic energy (KE) per unit mass the mth mode contributes in the kth velocity field.…”

“…In-cylinder flow structures generated during the intake stroke and modified during the compression stroke can be divided into two main forms of large scale motions (coherent structures), swirl and tumble. Swirl is the in-cylinder flow where the flow rotational axis is parallel to the cylinder axis while tumble is the flow with an axis perpendicular to that of the cylinder [3][4][5]. These coherent structures are mainly relying on the bore/stroke ratio, intake valve geometry, inlet port profile and the shape of the combustion chamber [6][7][8][9].…”

“…Therefore, in the recent years, the proper orthogonal decomposition analytical technique introduced firstly by Lumley [10] to the turbulence research community is considered as a powerful method to extract the most energetic structures in turbulent flows. The applications of POD have seen an increase in engine flow studies, in-cylinder flow analysis [4,11,12] cycle to cycle variations [13][14][15][16][17][18], variation of fuel spray structure [19,20] and combustion instability and misfire [14,21]. The aforementioned studies mainly have been concentrated on the evaluation of cycle-to-cycle variability in engines, either for air flow or for spray flow using POD.…”

Particle Image Velocimetry (PIV) Investigation of Blade and Purge Flow Impacts on Inter-Stage Flow Field in a Research Turbine

“…POD method was adopted to filter the instantaneous flow maps allowing a better visualization of the structures involved in the transition process of the boundary layer. El-Adawy et al [41] conducted experiments on a four-valve, pent-roof gasoline direct injection (GDI) engine head at different valve lifts using PIV. The POD technique was applied to characterize the flow structures at various valve lifts.…”