A comprehensive experimental investigation on the PFI spray impingement: Effect of impingement geometry, cross-flow and wall temperature

In this work, an experimental study on the effects of the impingement geometry, the cross-flow intensity and the wall temperature on the characteristics of an impinging port fuel injection (PFI) spray was conducted. The transient development of the impinging spray was recorded by a high-speed camera with Mie scattering. Based on the high-speed images, the spray tip penetration (S) and the impinged spray height (H_w) were obtained. The results show that with the increase of the impingement distance (L_w), S increases and H_w decreases at the same time after the impingement. As the impingement angle (θ_w) increases, S decreases while H_w first increases and then decreases. With the increase of the cross-flow velocity (U_c), less part of the spray impinges onto the wall, and S significantly increases. As the wall temperature (T_w) rises, S does not show much variation. However, H_w increases gently for T_w lower than 420 K, and it increases sharply for T_w higher than 420 K due to the Leidenfrost mechanism. The effects of the above factors (L_w, θ_w, U_c, T_w) on S and H_w were finally evaluated and compared through the introduction of a contribution index.