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 (theta(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, theta(w), U-c, T-w) on S and H-w were finally evaluated and compared through the introduction of a contribution index.