Robert E. Malecki

Towards Modeling Lean Blow Out in Gas Turbine Flameholder Applications

The objective of this study was to assess the accuracy of the large-eddy simulation (LES) methodology, with a simple combustion closure based on equilibrium chemistry, for simulating turbulent reacting flows behind a bluff body flameholder. Specifically, the variation in recirculation zone length with change in equivalence ratio was calculated and compared to experimental measurements. It was found that the present LES modeling approach can reproduce this variation accurately. However, it understated the recirculation zone length at the stoichiometric condition. The approach was assessed at the lean blow out condition to evaluate its behavior at the lean limit and to analyze the physics of combustion instability.

Application of an Advanced CFD-Based Analysis System to the PW6000 Combustor to Optimize Exit Temperature Distribution: Part I — Description and Validation of the Analysis Tool

This paper is the first of two parts that describes an advanced CFD-based analysis system, developed at Pratt & Whitney, which has been used to optimize the PW6000 combustor exit temperature distribution. It utilizes a CFD calculation through the entire combustor domain to predict temperature distribution at the combustor exit. In this part, all components of the analysis system are presented, including the CAD and grid generation approach used to represent the complex combustor geometry, the core CFD solver, the Lagrangian fuel spray model, and the combustion model. In addition, the predictive capability of the system is established by comparing calculated exit temperature profiles to full annular rig test data for three aircraft gas turbine engine combustors: PW4090, PW4098, and a low-emissions technology development combustor. Comparisons of combustor airflow distribution and pressure drop are also presented to verify the accuracy of the tool. The paper demonstrates that the CFD-based analysis system is capable of calculating exit temperature distribution for a range of combustor configurations, and thus can be utilized as a predictive design tool. Part II demonstrates this predictive capability by applying the analysis tool to optimize the PW6000 combustor exit temperature distribution for turbine durability and life. Copyright

Calculation of Internal Flows Using a Single-Pass, Parabolized Navier-Stokes Analysis

A single-pass, subsonic parabolized Navier-Stokes (PNS) procedure is developed to analyze three-dimensional viscous internal flows. Elliptic effects are incorporated by initializing the PNS code with the streamwise pressure gradient distribution obtained from a coarse grid Euler calculation. When the Euler code incorporates the transport of a «viscous-like» inlet vorticity profile, the rotational invisicid pressure distribution provides a good initialization for the single-pass PNS procedure