Rectangular Duct Hydraulic Diameter Calculation

Description 1

A rectangular duct has inside dimensions of 12x18 in. What is the hydraulic diameter of the duct? If 3 ft/min of air at 71°F flow through the duct, determine the Reynolds number.

1. The hydraulic diameter of the rectangular duct with inside dimensions of 12x18 inches is 14.4 inches.
2. (a) The effective diameter of the rectangular duct with internal dimensions of 4x1.5 inches is 2.18 inches.
(b) The hydraulic diameter of the rectangular duct is also 2.18 inches.
(c) The hydraulic radius of the rectangular duct is 0.545 inches.

Description 2

A rectangular duct has internal dimensions of 4*1.5 in. Calculate (a) effective diameter. (b) hydraulic diameter, and (c) hydraulic radius.

1. To find the hydraulic diameter of a rectangular duct, we need to use the formula:

Hydraulic Diameter = (4 * Area) / Perimeter

Given the inside dimensions of the duct are 12x18 inches, we can calculate the area as:

Area = Length * Width = 12 * 18 = 216 square inches

The perimeter can be calculated as:

Perimeter = 2 * (Length + Width) = 2 * (12 + 18) = 2 * 30 = 60 inches

Substituting the values into the formula, we get:

Hydraulic Diameter = (4 * 216) / 60 = 14.4 inches

2. (a) To find the effective diameter of a rectangular duct, we can use the formula:

Effective Diameter = (4 * Area) / Perimeter

Given the internal dimensions of the duct are 4x1.5 inches, we can calculate the area as:

Area = Length * Width = 4 * 1.5 = 6 square inches

The perimeter can be calculated as:

Perimeter = 2 * (Length + Width) = 2 * (4 + 1.5) = 2 * 5.5 = 11 inches

Substituting the values into the formula, we get:

Effective Diameter = (4 * 6) / 11 = 2.18 inches

(b) The hydraulic diameter of the rectangular duct is the same as the effective diameter, which is 2.18 inches.

(c) The hydraulic radius of a rectangular duct can be calculated by dividing the hydraulic diameter by 4. So, the hydraulic radius is 2.18 / 4 = 0.545 inches.

To know more about hydraulic diameter visit:

What is the formula to calculate the hydraulic diameter of a rectangular duct? How to find the effective diameter of a rectangular duct? What is the hydraulic radius of a rectangular duct? The formula to calculate the hydraulic diameter of a rectangular duct is: Hydraulic Diameter = (4 * Area) / Perimeter. To find the effective diameter of a rectangular duct, you can use the formula: Effective Diameter = (4 * Area) / Perimeter. The hydraulic radius of a rectangular duct is calculated by dividing the hydraulic diameter by 4.
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