End-Gas Autoignition Prediction Using Reverse Livengood-Wu Integral with Ignition Delay Time Equations for Gasoline Surrogate Fuel

A high-accuracy knocking or end-gas autoignition prediction model with low computational loads is necessary to develop thermal-efficiency improvement technologies for SI engines efficiently using computational techniques. Livengood-Wu integral has been applied widely as a simple and practical model to predict in-cylinder autoignition timing. In the present study, a high-accuracy model based on Livengood-Wu integral, has been investigated. First, a small set of ignition delay time equations for a premium-gasoline surrogate fuel has been developed, which can reproduce the temperature-, pressure-, equivalence ratio-, and EGR-dependences of ignition delay time under constant-volume condition, produced using a detailed reaction mechanism. Then, Livengood-Wu integral using the ignition delay time equations has been applied to predict in-cylinder autoignition timing produced using the detailed reaction mechanism. Numerical analyses have found X of Livengood-Wu integral and error factors in the prediction. Heat can represent X of Livengood-Wu integral. Last, iterative reverse Livengood-Wu integral using an error correction equation has been proposed, which can decrease the error in the prediction using normal Livengood-Wu integral.