Turbulator Passage Elements

Cross-section shape allows user to specify geometry in four different ways.

1: Annular with Inner and Outer Diameter specified (Internally, the solver computes area and perimeter.)

2: Circular with Area specified (Internally, the solver computes diameter and perimeter.)

3: Circular with Diameter specified (Internally, the solver computes area and perimeter)

4: Arbitrary Shape with Area as well as Hydraulic Diameter specified. (Internally, the solver computes the perimeter.)

Inner Annulus Diameter

This is needed only when CS_MODE=1.

Outer Annulus Diameter (inches)

This is needed only when CS_MODE=1.

Cross-section area

If area is non-constant, then AREA is exit area.

This field is needed only when CS_MODE=2 or 4.

Diameter (or Hydraulic Diameter for non-circular cross-sections)

If diameter is non-constant, then this is exit diameter.

This field is need only when CS_MODE=3 or 4.

Short Passage Length

Since friction losses a modelled as occurring at the exit, properties (area, velocity, pressure, etc.) should not vary too much from inlet to exit. Thus, the Short Passage is good for modeling small L/D channels. For longer L/D channels, the tube element is preferred.

Wall texture option

1: Smooth or Rough wall (uses Colebrook-White)

2: Turbulated Wall (uses Webb)

Turbulator Rib Height (inches)

Needed if WALL_TYPE=2

Center-to-center distance between turbulator ribs (inches)

Needed if WALL_TYPE=2

Roughness value

When FRIC_MODE=1 (friction calculated with Swamee-Jain approximation to Colebrook-White), roughness can be provided. Sand-grain roughness is the default type, since that is what Moody, Colebrook-White, Swamee, etc. are based on.

Friction options

0: No friction

1: Fixed Smooth/Rough wall Friction Coefficient; Turbulator Friction Coefficient = 0.0

2: Colebrook-White Smooth/ Rough wall Friction Coefficient; Turbulator Friction Coefficient = 0.0

3: Fixed Smooth/Rough wall Friction Coefficient; Fixed Turbulator Friction Coefficient

4: Colebrook-White Smooth/ Rough wall Friction Coefficient; Fixed Turbulator Friction Coefficient

5: Fixed Smooth/Rough wall Friction Coefficient; Webb Turbulator Friction Coefficient

6: Colebrook-White Smooth/ Rough wall Friction Coefficient; Webb Turbulator Friction Coefficient

Friction multiplier for smooth/rough friction coefficient

(FM_SMOOTH)

User-specified multiplier for friction coefficient on the smooth/rough wall

This should only be used with calculated friction values. FMULTs are often used to account for roughness effects, so FMULT should probably be used only when ROUGHNESS =0.

(Can be 0 or higher)

Friction multiplier for turbulator friction coefficient

(FM_TURB)

User-specified multiplier for friction coefficient on turbulators

This should only be used with calculated friction values.

(Can be 0 or higher)

Reference rotor index for user-supplied swirl.

Stationary (Database Value = 0.0)

Rotor 1 (Database Value = 1.0): Points to general data Shaft 1 Rotor Speed.

Rotor 2 (Database Value = 2.0): Points to general data Shaft 2 Rotor Speed

Rotor 3 (Database Value = 3.0): Points to general data Shaft 3 Rotor Speed

Rotates with Air (database Value = -1.0): Element RPM is based on upstream fluid RPM

Radius (in). Radial distance between the orifice inlet center and the engine centerline.

(Do not use zero unless the orifice is not rotating)

Angle between the element centerline at the entrance of the element and the reference direction.

If the element is rotating or directly connected to one or more rotating elements, the reference direction is defined as parallel to the engine centerline and the angle is the projected angle in the tangential direction. Otherwise, the reference direction is arbitrary but assumed to be the same as the reference direction for all other elements attached to the upstream chamber.

THETA for an element downstream of a plenum chamber has no impact on the solution except to set the default value of THETA_EX.

(See also THETA_EX)

Angle between the element centerline at the entrance of the element and the THETA direction. (spherical coordinate system)

PHI for an element downstream of a plenum chamber has no impact on the solution except to set the default value of PHI_EX.

(See also PHI_EX)

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Exit K Loss:

Axial (K_EXIT_Z)

Tangential (K_EXIT_U)

Radial (K_EXIT_R)

Head loss factors in the Z, U, and R directions based on the spherical coordinate system of theta and phi. (Default value provides no loss).

Refer General solver theory sections for more details about this input

Angle between the orifice exit centerline and the reference direction.

THETA_EX is an optional variable to be used if the orientation of the element exit differs from that of the element inlet.

The default value (THETA_EX = -999) will result in the assumption that THETA_EX = THETA.

Other values will be interpreted in the manner presented in the description of THETA.

Angle between the orifice exit centerline and the THETA_EX direction.

PHI_EX is an optional variable to be used if the orientation of the element exit differs from that of the element inlet.

The default (PHI_EX = -999) will result in the assumption that PHI_EX = PHI.

Other values will be interpreted in the manner presented in the description of PHI.

This tells the solver how to interpret QIN.

0: No heat added

1: Heat added is in Btu/sec

2: Head added is in Btu/Lbm (proportional to element mass flow rate)

The user can choose which solution algorithm to use.

1: Compressible Fluid (using 0.5*rho*v^2 in denominator of K and Cp relations) – preferred for future modeling

2: Incompressible Fluid (also using 0.5*rho*v^2 in denominator of K and Cp relations) – preferred when matching past results

3: Compressible with Compressible K (using Pt-Ps in denominator of K and Cp relations) – preferred only if you know that your K or Cp data is based on Pt-Ps

4: Incompressible liquid

Head Loss that is in addition to friction losses

The Additional Head Loss is distributed the same as the friction losses (all at the exit). Since ordering of Head Losses matters for compressible flow, care should be taken to get proper modeling with this option.

Nomenclature:

P = Pressure

V = Velocity

A = Area

PR = Pressure Ratio (Pt/Ps)

TR = Temperature ratio (Tt/Ts)

Pt: Total pressure

Ps: Static Pressure

Tt: Total temperature

Subscripts:

in =inlet station

ex =exit station

Fluid compressibility option

(INCOMPRESSIBLE, COMPRESSIBLE, or FULLY_COMPRESS)

Fully compressible means the fluid is compressible and the K-relationship is compressible too.

Static pressure relative to the rotational reference frame (i.e. rotor) at the transition inlet.

Limited by critical pressure ratio for supersonic flows when inlet area is smaller than exit area.

Static pressure relative to the rotational reference frame (i.e. rotor) at the transition exit.

Limited by critical pressure ratio for supersonic flows.

Heat added

Positive values indicate heat added to the fluid; negative values indicate heat removed.