Computer simulations are compared with measurements of the three-dimensional, unsteady scavenging flows of a motored two-stroke engine. Laser Doppler velocimetry measurements were made on a modified Suzuki DT-85 ported engine. Calculations were performed using KIVA-3, a computer program that efficiently solves the intake and exhaust port flows along with those in the cylinder. Measured and computed cylinder pressures and velocities are compared. Pressures agree well over the cycle as do the velocities at the intake ports. In-cylinder velocities differ in detail, but the tumbling motion in the cylinder is well replicated in vertical plane passing through the cylinder axis. 20 refs., 7 figs., 3 tabs.

This paper describes and illustrates the principal differences between the newly-released KIVA-II and the KIVA computer programs. Both programs are for the numerical calculation of two- and three-dimensional fluid flows with chemical reactions and sprays. Because of improvements to KIVA-II, it is faster, more accurate, and applicable to a wider variety of problems involving combustion and two-phase flow.

This report documents the KIVA-II computer program for the numerical calculation of transient, two- and three-dimensional, chemically reactive fluid flows with sprays. KIVA-II extends and enhances the earlier KIVA code, improving its computational accuracy and efficiency and its ease-of-use. The KIVA-II equations and numerical solution procedures are very general and can be applied to laminar or turbulent flows, subsonic or supersonic flows, and single-phase or dispersed two-phase flows. Arbitrary numbers of species and chemical reactions are allowed. A stochastic particle method is used to calculate evaporating liquid sprays, including the effects of droplet collisions and aerodynamic breakups. Although the initial and boundary conditions and mesh generation have been written for internal combustion engine calculations, the logic for these specifications can be easily modified for a variety of other applications. Following an overview of the principal features of the KIVA-II program, we describe in detail the equations solved, the numerical solution procedure, and the structure of the computer program. Sixteen appendices provide additional details concerning the numerical solution procedure. 67 refs., 29 figs.

Since its public release in 1985, the KIVA computer program has been used for the time dependent analysis of chemically reacting flows with sprays in two and three space dimensions. This paper describes some of the improvements to the original version that have been made since that time. The new code, called KIVA-II, is planned for public release in early 1988. KIVA-II improves the earlier version in the accuracy and efficiency of the computational procedure, the accuracy of the physics submodels, and in versatility and ease of use. Numerical improvements include the use of the ICE solution procedure in place of the acoustic subcycling method and the implementation of a quasi-second-order-accurate convection scheme. Major extensions to the physical submodels include the inclusion of an optical kappa-epsilon turbulence model, and several additions to the spray model. The authors illustrate some of the new capabilities by means of example solutions.

This paper summarizes a comprehensive numerical model that represents the spray dynamics, fluid flow, species transport, mixing, chemical reactions, and accompanying heat release that occur inside the cylinder of an internal combustion engine. The model is embodied in the KIVA computer code. The code calculates both two-dimensional (2D) and three-dimensional (3D) situations. It is an outgrowth of the earlier 2D CONCHAS-SPRAY computer program. Sample numerical calculations are presented to indicate the level of detail that is available from these simulations. These calculations are for a direct injection stratified charge engine with swirl. Both a 2D and a 3D example are shown.

In this paper we present a method that numerically solves the full two-dimensional, time-dependent Navier-Stokes equations with species transport, mixing, and chemical reaction between species. The generality of the formulation permits the solution of flows in which deflagrations, detonations, or transitions from deflagration to detonation are found. The solution procedure is embodied in the RICE computer program. RICE is an Eulerian finite difference computer code that uses the Implicit Continuous-fluid Eulerian (ICE) technique to solve the governing equations. We first present the differential equations of motion and the solution procedure of the RICE program. Next, a method is described for artificially thickening the combustion zone to dimensions resolvable by the computational mesh. This is done in such a way that the physical flame speed and jump conditions across the flame front are preserved. Finally, the results of two example calculations are presented. In the first, the artificial thickening technique is used to solve a one-dimensional laminar flame problem. In the second, the results of a full two-dimensional calculation of unsteady combustion in two connected chambers are detailed.

of the acoustic subcycling method and the implementation of a quasi-second-order-accurate convection scheme. Major extensions to the physical submodels include the inclusion of an optional k-epsilon turbulence model, and several additions to the spray model. We illustrate some of the new capabilities by means of example solutions. 25 refs., 7 figs.

A method for increased accuracy in Eulerian fluid dynamics calculations is described. The essence of the method is local cancellation of low-order, diffusional truncation errors. These errors are the source of nonlinear numerical instabilities. The methodology is described in general and specific application is made to the transient, two-dimensional flow equations for chemically reacting mixtures. Two example problems are solved to illustrate the method. For comparison, the same problems are solved with an artificial viscosity technique. (auth)

The extremely complex species mixing phenomena that occur in flowing, continuous wave, chemical lasers have been investigated using a computer model. The model calculates the dynamics of the various species coupled with finite rate chemical reactions. Studies have been made of several laser designs in which fluorine is admitted into the laser cavity through an array of supersonic nozzles where it mixes and reacts with hydrogen entering from separate orifices. The chemical reactions produce HF in excited vibrational states and release significant amounts of heat. Of particular interest are the effects on mixing of lateral pressure gradients that result from the heat release and the presence of embedded shocks in the flow. The numerical procedure uses finite difference approximations to the full time-dependent Navier-Stokes equations in two space dimensions together with species transport equations and chemical kinetics. Comparisons between the calculational results and chemiluminescence photographs of the flow field show excellent agreement for the spatial distribution of HF in the cavity. The results help to explain experimental observations and suggest new directions for achieving optimum laser efficiency.