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Combustion CFD Simulation Services | Preferred Utilities Mfg

Engineering Services & Specification Support

Combustion CFD Simulation

Data-Driven Design Before You Build

Getting burner geometry right the first time depends on understanding how fuel, air, and heat interact inside the combustor before equipment is built. If those interactions are unclear, costly redesigns and missed emissions targets can follow.

This page reviews two recent computational fluid dynamics (CFD) studies and identifies key findings for specifying engineers and combustion equipment operators, along with how Preferred Utilities applies this work to burner design.

CFD Study 01

Swirler Diameter Investigation

The swirler imparts rotational motion to combustion air, which stabilizes the flame and drives fuel-air mixing. Swirler diameter is a key design variable that affects pressure drop, mixing quality, and NOx formation.

The Question

Does a smaller swirler diameter, which reduces pressure drop, also reduce NOx emissions as theory might suggest?

The Finding

No. CFD results showed the opposite: smaller diameters increased bypass oxidizer flow and combustor unmixedness, raising NOx significantly despite the lower pressure drop.

  • Three diameters evaluated: 16", 20", and 24"
  • Smaller diameter reduced pressure drop but weakened the recirculation zone
  • Weaker recirculation led to poorer fuel-air mixing and higher localized flame temperatures
  • Theoretical swirl number alone did not predict actual combustor-scale mixing behavior
30.2
ppm NOx @ 24"
86.8
ppm NOx @ 16"
3
Diameters Tested
Swirler diameter CFD contour plot results comparing 16-inch, 20-inch, and 24-inch configurations

Metrics evaluated: temperature contours, velocity streamlines, unmixedness, NOx contours, pressure drop trend plots.

CFD Study 02

Fuel Injection Penetration Angle Investigation

Injector angle relative to swirl direction is a key mixing control parameter. This study investigated whether inward-directed fuel injection could improve combustor-scale mixing and reduce thermal NOx without creating localized high-temperature regions.

The Question

Is there a single "best" injector angle, or does NOx keep improving the further inward the fuel jet is rotated?

The Finding

An optimal angle exists. The 10° inward configuration produced the lowest NOx and best mixing. 20° inward showed a partial NOx rebound and higher pressure drop.

  • Three configurations evaluated: baseline (0°), 10° inward, and 20° inward
  • 10° inward penetration produced the lowest NOx and unmixedness of all cases tested
  • 20° inward increased core interaction and aerodynamic resistance without further NOx benefit
  • Results confirm injector angle is a strong, independent design variable for emissions control
37.2
ppm NOx Baseline
13.8
ppm NOx @ 10°
63%
NOx Reduction
Fuel injection penetration angle NOx trend results comparing baseline, 10 degree, and 20 degree configurations

Metrics evaluated: NOx, unmixedness, pressure drop, swirl intensity, iso-volume visualization, temperature distribution.

Our Approach

How We Run a CFD Study

  • Define operating conditions, fuel type, and geometry parameters with your team
  • Build and mesh the combustor model and establish a converged baseline solution
  • Run parametric simulations across design variations using flamelet/PDF chemistry modeling
  • Deliver contour plots, trend data, and manufacturable design recommendations

Our CFD work is performed by engineers who also design and build the equipment. Findings connect directly to manufacturable changes, not just theoretical optima. Preferred Utilities Manufacturing Corporation has designed and built combustion equipment since 1920.

Need a CFD Study for Your Application?

Reach out to our engineering team to discuss your burner geometry, fuel type, and emissions targets.

Contact Our Engineers

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