Davis Exhaust Plume Trajectory Analysis

Empirical Exhaust Plume Prediction

There are principally four ways to assess/predict the behaviour of an exhaust plume:
i) full scale measurements (sea trial);
ii) scale model testing in a wind or water tunnel;
iii) numerical simulation using Computational Fluid Dynamics (CFD); and
iv) empirical correlations based on already existing measured data.
Full scale and model testing are expensive and take a great deal of time. It becomes difficult to isolate the environmental variables in which you are interested.

Davis has developed an empirical prediction method using a set of equations to define the behaviour of the exhaust that correlates to a number of past experimental data sets. Presently Davis uses almost exclusively correlations established by Baham in 1977. Baham’s correlations are based on an extensive body of measured data from a British cruiser and the full scale U.S. DD-964 measurements. DAVIS has added an additional equation to deal with the situation of the stack not being perpendicular to the wind.

These correlations are integrated into a Davis software package to determine impingement temperatures at abitrary locations relative to the stack exit for a range of wind speeds and headings. This information is combined with probability data for wind speeds and headings depending on the global location of the installation.

Empirical Analysis of Exhaust Impingement on a Drilling Derrick

CFD Gas Turbine Exhaust Analysis

CFD Simulation Gas Turbine Exhaust on Naval Vessel

The empirical method provides a rapid analysis of a wide range of operational conditions but does not account for complex 3-dimensional flow effects such as recirculation, obstructions or non-uniform exhaust distributions. Computational Fluid Dynamic (CFD) analysis is performed on the precise geometry and operational conditions of the given case.

Davis has performed numerous CFD based exhaust trajectory and impingement studies. By combining the empirical method with the CFD method, Davis analysts can ensure that valuable CFD computer time is run against the operational and environmental conditions that are important to the case at hand. This is the most effective way to rapidly generate a complete and accurate assessment of exhaust impingement on a platform.

BouyanT Exhaust Plumes

Large gas turbine power generating stations emit a large buoyant plume which can exhibit a significant updraft in low winds even at high altitudes. Aviation or environmental concerns place restrictions on velocity, size, temperature, and concentration in plumes at large distances from the exit of the exhaust stack. Davis utilizes both empirical and CFD based techniques for assessing buoyant plumes and assessing the benefits of exhaust gas cooling technology.