Geometry > Circulating Geometry > Diameter D

Diameter D

The diameter D is the outer diameter or Inscribed Circle Diameter.

HCM does not use the D.

The relationship between capacity and D is more complicated than other parameters.

For a given circulating flow the increase in capacity, shown below, is moderate.

However, increasing D gives greater increases in capacity the larger the circulating flow as shown below.

Capacity is a small when opposing flows are large, so having a geometric parameter that increases capacity most when capacity is least is very useful.

However, moderately increasing D increases the ROW disproportionately. On the contrary, moderately reducing the D can release enough land to widen entries and increase flare lengths sufficiently to achieve a large net gain in capacity.

The effect of varying D should be checked with the accident models.

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