7. Object-related Q1 settings for FLAIR HVAC-specific Object Types

Contents

7.1 Diffuser
7.2 Fire
7.3 Jetfan
7.4 Sprayhead
7.5 Person
7.6 People



7.1 Diffuser

The diffuser dialogs are described in section 3.1 above.

The implementation of diffusers follows the recommendations of ASHRAE RP-1009, 'Simplified Diffuser Boundary Conditions for Numerical Room Airflow Models'. The diffuser object can generate the following Q1 settings, in addition to the standard size and position settings.

Diffuser type:
> OBJ, DIFF-TYPE,
type

where type can be one of

Diffuser plane:
> OBJ, PLANE,
dir

where dir can be X, Y or Z. This sets the plane the diffuser is located in.

Diffuser diameter (for ROUND or VORTEX diffuser)
> OBJ, DIAMETER,
diam

The default diameter is 0.3m. For the other diffuser types, the size is taken from the SIZE attribute.

Diffuser origin:
> OBJ, CENTRE,
xpos, ypos, zpos

This sets the coordinates of the centre of the diffuser in the plane, and the location of the face of the diffuser in contact with the mounting surface in the third direction. These values override the POSITION attribute settings. If the CENTRE is not set, it is deduced from the POSITION and SIZE settings. For DISPLACEMENT diffusers, the POSITION and SIZE attributes are used directly.

Active faces (4-WAY and DISPLACEMENT only):
> OBJ, X-FACES,
0/1, 0/1
> OBJ, Y-FACES, 0/1, 0/1
> OBJ, Z-FACES, 0/1, 0/1

where 0 means inactive, 1 means active for the low-coordinate and high coordinate faces respectively.

Supply units:
> OBJ, SUPP-UNIT,
unit

where unit can be L/S for supply in litres/s, or M^3/S for supply in cubic metres/s. The default is l/s.

Supply volume:
> OBJ, SUPP-VOL,
Q

where Q is the volumetric flow rate supplied by the diffuser in the selected unit system. The default is 250 l/s.

Supply pressure:
> OBJ, SUPP-P,
Psupp

where Psupp is the supply pressure (in Pa) relative to the set reference pressure (usually 1atm). The default is zero relative pressure, meaning atmospheric absolute pressure. This value is used to calculate the density at the inlet.

Supply temperature:
> OBJ, SUPP-T,
Tsupp

where Tsupp is the temperature of the supplied air, relative to the reference temperature (usually 273K). The default is 25 C. This value is used to calculate the density at the inlet.

Diffuser characteristics

Round, vortex and rectangular diffusers can be characterised by either the effective area, or by the throw, terminal velocity and jet decay constant.

If the effective area is set, the effective height is deduced by dividing the effective area by the perimeter P.

Heff = Aeff/P

This is used to set the depth of the diffuser normal to the plane. The inlet velocity is obtained by dividing the supply flow-rate by the effective area.

Uin = Q/Aeff

Effective area (only if Throw not set):
> OBJ, EFF-AREA
, Aeff

where the default effective area is 0.5 (50%).

If the throw T (distance at which the terminal velocity is reached), terminal velocity Ut (velocity at the throw distance) and jet decay constant K are set, the plane linear free jet formula:

Ut = Uin K (Heff/T)

is used to calculate the discharge velocity Uin from:

Uin = Ut2 T P /(K2 Q)

where P is the perimeter of the diffuser. The effective height can now be deduced from:

Heff = Q/ (Uin P)

A grille/nozzle diffuser is treated in a similar fashion, except that the axi-symmetric free jet formula is slightly different:

Ut = Uin K (Aeff)/T

The actual discharge velocity is:

Uin = Ut2 T2/(K2 Q)

The velocity at which mass enters the system is based on the actual frontal area A:

U = Q/A

Throw settings (only if Effective area not set):
> OBJ, THROW,
T
> OBJ, TERM-VEL, Ut
> OBJ, DECAY-CON, K

where the default values are T=2.0, Ut = 0.75 and K=1.1. Values of K for typical situations can be found in the ASHRAE handbook of Fundamentals.

Vortex diffusers also require the swirl angle in degrees to be specified.

Swirl angle (VORTEX diffusers):
> OBJ, SWIRL-ANG,
S

where the default swirl angle S is zero.

Area ratio (DISPLACEMENT diffuser only):
> OBJ, AREA-RATIO
', Arat

sets the ratio between the actual (open) area and the nominal (dimensional) area for all active faces.

Turbulence inlet value  - all diffuser types:
> OBJ, TURB-INTENS, I

where I is the turbulence intensity (%) of the inlet stream. The inlet values of k and e are deduced from:

KEin = (I*Uin)2
EPin = 0.1643*KEin3/2/(0.5*Heff)

or

> OBJ, KE_IN, kein
> OBJ, EP_IN, epin

where kein and epin are the k and e values to be used.

Mounting face for ROUND, VORTEX, RECTANGULAR and 4-WAY, or object side for GRILLE:
> OBJ, SIDE, High/Low

For round, vortex, rectangular or 4-way diffusers, High means the unit is mounted its increasing-coordinate face e.g. square diffuser in X plane mounted at x=Xmax. Low means the unit is mounted on the decreasing coordinate face e.g. square diffuser in X plane mounted at x=Xmin.

For grille diffusers, it denotes which side of the grille the flow is issuing from.

Direction and symmetry flags for GRILLE diffusers:

X-plane
> OBJ, ANGLE_Y-X,
ang_y-x
> OBJ, ANGLE_Z-X, ang_z-x
> OBJ, SYM_V, yes/no
> OBJ, SYM_W, yes/no

Y-plane
> OBJ, ANGLE_X-Y, ang_x-y
> OBJ, ANGLE_Z-Y, ang_z-y
> OBJ, SYM_U, yes/no
> OBJ, SYM_W, yes/no

Z-plane
> OBJ, ANGLE_X-Z,
ang_x-z
> OBJ, ANGLE_Y-Z, ang_y-z
> OBJ, SYM_U, yes/no
> OBJ, SYM_V, yes/no

For each plane, these control the angle of the jet normal to the grille, and whether the velocities are symmetric or not.

Units for inlet water vapour:
> OBJ, HUNITS, unit

where unit can be:

Inlet scalar values:
> OBJ, INLET_scal
, value

where scal is the name of a solved scalar (often SMOK), and value is the inlet value. If there is more than one solved scalar, there will be one such line for each scalar.


7.2 Fire

The fire dialogs are described in section 3.1 above.

The fire object can generate the following Q1 settings, in addition to the standard size and position settings.

Pre-ignition temperature
> OBJ, PRE-TEMP
, Tpre

where Tpre is the temperature of the combusting material before combustion. The units are degrees C.

Mass source
> OBJ, MASS-SOURCE
, form

where form is one of:

Fixed Rate Mass Source value
> OBJ, FXD-MASS
, M

where M is the constant mass source for the object in kg/s.

Pool fire settings
> OBJ, BETA
, B
> OBJ, COEFA, a
> OBJ, COEFB, b
> OBJ, COEFC, c

where the fire area grows with time according to

Area = a + b * tc,

and the mass release grows as

Mass = Area *( 1-exp(-B*Area.5))

Piecewise Linear with Time settings
> OBJ, MSEG_i,
ti, Mi

where i goes from 1 to the number of segments+1, ti is the time at the start of the segment and Mi is the mass release rate in kg/s for the object at time ti. The last MSEG_ line sets the time and mass release at the end of the last segment.

From table file settings
> OBJ, MASS-FILE
, file_name

where file_name is the name of the file containing the table of values

Heat Source
> OBJ, HEAT-SOURCE
, form

where form is one of

Fixed Temperature Value
> OBJ, FXD-TEM,
Tfix

where Tfix is the fixed temperature in degrees C

Fixed Power Value
> OBJ, FXD-FLU
, Qfix

where Qfix is the constant heat release rate in W.

Linear with Temperature settings
> OBJ, COEFFS,
a, b
> OBJ, LIMITS, Tmin, Tmax

where the heat source in Watts for each cell within the object is

        Q = a+b*(min(Tmax, max(T+TEMP0)),Tmin)

Power of Time settings
> OBJ, COEFFS
, a, b
> OBJ, QMAX, Qmax

where the heat source in Watts for each cell within the object is

        Q = max(Qmax, a*(t-t0)b) where t is the time in seconds, and t0 is the time at the start of the fire.

Piecewise Linear with Time settings
> OBJ, QSEG_i
, ti, Qi

where i goes from 1 to the number of segments+1, ti is the time at the start of the segment and Qi is the heat release rate in Watts for the object at time ti. The last QSEG_ line sets the time and heat release at the end of the last segment.

From table file settings
> OBJ, HEAT-FILE
, file_name

where file_name is the name of the file containing the table of values

Scalar Source
> OBJ, SCALAR-SOURCE
, form

where form is one of

Inlet value of scalar
> OBJ, INLET_scal
, val

where scal is the name of the scalar, and val is its value. There will be one such line for each scalar.

Combustion efficiency
> OBJ, EFFICIENCY,
eff

where eff is the combuston efficiency, taken to be 1/(1+s) where s is the stoichiometric ratio.

Heat of Combustion
> OBJ, HEAT-COMB, Hc

where Hc is the heat of combustion in J/kg.


7.3 Jetfan

The jetfan dialogs are described in section 3.2 above.

The jetfan object can generate the following Q1 settings, in addition to the standard size and position settings.

FAN Geometry
> OBJ, FANTYPE,
type

where type can be rectangular or round.

Fan Speed
> OBJ, VELOCITY
, Velocity

where Velocity is the fan velocity in m/s, defaulted to 22 m/s.

Heat load
> OBJ, HEAT_LOAD,
Q

where Q is the heat output in Watts associated with the fan, defaulted to zero.

The rotation centre of a Jetfan object is set to the object centre.

Turbulence intensity
> OBJ, TURB_INTENS
, I

where I is the turbulence intensity for the jetfan in %. If the line is absent, a value of zero is assumed and the jetfan has no direct influence on the turbulence quantities.


7.4 Spray Head

The spray-head dialogs are described in section 3.1 above.

The sprayhead object can generate the following Q1 settings, in addition to the standard size and position settings.

Spray Axis
> OBJ, AXIS,
dir

where dir can be X, Y or Z

Spray head radius
> OBJ, Radius
, rad

Spray head origin
> OBJ, ORIGIN
, x0, y0, z0

The axis, radius and origin settings are combined to generate the object bounding box size and position, overriding the standard SIZE and POSITION settings

The following settings only appear for transient cases.

Calculate link temperature
> OBJ, LINK_T
, yes/no

When set to yes, the spray will be activated when the link temperature at the spray location reaches the activation temperature. This time will be printed in the RESULT file, and the link temperatures will be written to tlinkn.csv.

When the link temperature is active, the duration of spraying after activation is written as:
> OBJ, TIME_SPRAY, Tdur

where Tdur is the duration of spraying in seconds.

Activation Temperature
> OBJ, T_ACTIVATE
, Tact

where Tact is the required activation temperature

Response time Index
> OBJ, RTI
, rti

where rti is the required Response Time Index

Number of injection ports
> OBJ, PORTS,
Nports

Total volume flow rate
> OBJ, TOTAL-VOL
, Vol

Total velocity
> OBJ, TOTAL-VEL
, Vel

Spray angle
> OBJ, ANGLE
, ang

Inflow temperature
> OBJ, TEMPERATURE
, Tin

Mean diameter for droplets
> OBJ, DMEAN,
Dmean

Number of droplet size ranges
> OBJ, NSIZE
, Nsize

Minimum droplet diameter
> OBJ, DMIN
, Dmin

Maximum droplet diameter
> OBJ, DMAX,
Dmax

Spread exponent
> OBJ, SPREAD_EXP
, S


7.5 Person

The person dialogs are described in section 3.1 above.

The person object can generate the following Q1 settings, in addition to the standard size and position settings.

Posture
> OBJ, POSTURE
, post

where post can be standing, sitting, or user.

Direction
> OBJ, FACING
, dir

where dir can be one of +X, -X, +Y or -Y

Size
> OBJ, WIDTH
, wid
> OBJ, DEPTH, dep
> OBJ, HEIGHT, hig

where wd, dep and hig are the width, depth and height of the person object in m. The defaults are wid=0.4m, dep=0.25m and hig=1.8m for standing, and wid=0.4m, dep=0.5, hig=1.45m for sitting.

Source form
> OBJ, SOURCE-FORM
, form

where form can be Total-heat or Fixed-temperature

Heat source
> OBJ, HEAT
, Q

or

> OBJ, TEMPERATURE, T

where Q is the total heat release rate in W, and T is the temperature in Centigrade.

Initial Temperature
> OBJ, INI_TEMP,
Tstart

where Tstart is the initial temperature in Centigrade.

Scalar source
> OBJ, INLET_scal
, val

where scal is the name of the scalar, and val is its value. There will be one such line for each scalar.


7.6 People

The people dialogs are described in section 3.1 above.

The people object can generate the following Q1 settings, in addition to the standard size and position settings.

Source form
> OBJ, SOURCE-FORM
, form

where form can be Total-heat or Fixed-temperature

Heat source
> OBJ, HEAT
, Q

or

> OBJ, TEMPERATURE, T

where Q is the total heat release rate in W, and T is the temperature in Centigrade.

Initial Temperature
> OBJ, INI_TEMP,
Tstart

where Tstart is the initial temperature in Centigrade.