The flow through revolving openings is of involvement to the interior decorator of machine incorporating such characteristics. For these systems, the internal air system later frequently must go through through the rotating constituents. Excessive supply of internal air consequences in a debasement of the overall on the job efficiency of machines while a deficit of it may do critical harm to the constituents due to overheating. The demand to supply air circulation in revolving system as a method of chilling, chamber waterproofing and bar of hot gas come ining pits in stuffs, has become an of import affair in recent industries. Most of the research carried out in the yesteryear has been on stationary openings and merely late has attending shifted to revolving systems. In this paper, the pumping consequence of revolving openings in forestalling the seal escape is investigated so compared to the stationary 1. A trial rig is designed and built to execute the experiments. The consequence of assorted flow parametric quantities is observed. The proposed method can help interior decorator to happen optimize openings constellation in forestalling non-contact seal escape.
Keywords: rotating openings, stationary opening, seal escape, pumping consequence
The flow through revolving openings is of involvement in revolving equipment such as turbines, compressors, extractors, pumps, motors, journal bearings, alternators, and generators. For these systems, the internal air system later frequently must go through through the rotating constituents. The internal air system does non lend straight to the power end product alternatively it is used for of import maps like rotor and stator chilling, blade and phonograph record chilling, accessary unit chilling, bearing chamber waterproofing and bar of hot gas consumption into disc pits [ 1 ] . The alternator or motor generates considerable sum of heat and the internal air is used as the chilling medium. Excessive supply of internal air consequences in a debasement of the overall on the job efficiency of machines while a deficit of it may do critical harm to the constituents due to overheating.
As for old use particularly in turbines, the labyrinth seal has been used as the method. Nevertheless, the demand for a better seal escape bar, with a better design, better efficiency, and compact form has encouraged uninterrupted surveies to be done. For revolving openings, due to the rotary motion of radial phonograph record there will be a higher mass flow rate to go through through the openings. This pumping consequence theoretically will supply better non-contact seal since the higher mass flow rate is pumping to the seal country.
Most of the old research concentrated on the flow feature over the opening. The earliest survey on revolving openings was done by Meyfarth and Shine [ 2 ] which studied features over the openings in term of the digressive velocity parametric quantity S, which is the ratio of the digressive velocity of the opening and the axial speed of the flow into the opening. Idris et Al. [ 3 ] investigated the flow within inclined revolving openings and found that the most of import parametric quantity act uponing the discharge coefficient is the angle of incidence. Idris and Pullen [ 4 ] investigated the pumping consequence of the rotating opening and its correlativity with the discharge coefficient.
This paper is about look intoing the pumping consequence of revolving openings in cut downing seal escape. Several flow parametric quantities such the sum of recess mass flow rate and the rotary motion velocity of openings is applied to give the best non contact seal. The consequence of the rotating opening is besides compared with the stationary openings.
2. EXPERIMENTAL APPARATUS
A conventional drawing of trial rig is shown in Figure 1. The chief parts of the trial rig includes radial revolving phonograph record with opening inserts, chief shaft, fan, suction cone, discharge chamber, and besides the 1520 millimeter extension pipe [ 5 ] .
The air flow pumps into to the trial rig by the fan near the recess suction. The recess suction has diameter of 100 millimeter. The extension pipe with 1520 millimeter long and diameter of 320 millimeter is used so that the discharge flow from the fan will be to the full developed when it reaches the rotating openings. The mercantile establishment subdivision is divided through four of gum elastic hose holding internal diameter of 25 millimeters, so all of the hosieries connected to a discharge chamber with diameter of 100mm.
100 Dia. Swivel wheel
Radial revolving phonograph record with inserts
100 Dia. Rigid wheel
M8 Bolt c/w Hex nut
M10 Bolt c/w s.w & A ; Hex nut
Air discharge chamber
Figure 1: Schematic of the Test Rig
The radial rotating phonograph record has outer diameter of 800 m, while the diameter of the lodging is 814 millimeter, so the seal spread is 7 millimeter. Four openings inserts are attached to the phonograph record. The openings inserts are replaceable so the assorted geometry of opening can be used.
The radial rotating phonograph record is connected to the motor through the chief shaft that can defy the rotary motion up to 15,000 revolutions per minute. The motor used is an AC motor with a rated power of 1100 Watt and rated velocity of 2870 rev/min. Drive is transmitted to the chief shaft via toothed cogwheel and belt, wit a ratio of 4:1.
The air velocity at the recess and mercantile establishment is measured utilizing wind gauge. Tachometer is used to mensurate the velocity of fan and the revolving radial phonograph record.
3. DATA ANALYSIS
The derivations mass flow rates are based from some fluid mechanics equations, such as Bernoulliaa‚¬a„?s equation, steady flow energy equation and discharge coefficient equation.
If the flow steady, irrotational, inviscid, and incompressible, isentropic flow for a stationary opening is considered, the derivation of mass flow is based of Bernoulliaa‚¬a„?s equation.
( 1 )
Figure 2: Flow through sharp-edge opening
For the flow shown in Figure 2, along with the continuity equation
( 2 )
consequences in the mass flow equation:
( 3 )
Assuming V1 is little ( i.e A1 & gt ; & gt ; A2 from mass continuity equation )
( 4 )
Where A = cross sectional country of opening.
4. Analysis OF THE STATIONARY ORIFICE
The trial is performed with go throughing the fluid through the trial rig with stationary opening. The opening insert used has hole diameter of 7 millimeters with hole length 14 millimeter, and the disposition angle is zero grade. The fan velocity of trial rig is varied from 160 revolutions per minute to 837 revolutions per minute, so the mass flow rate at the recess and mercantile establishment is investigated. Table 1 below shows the mass flow rate at the recess and the mercantile establishment and the loss of mass flow rate for each velocity of fan.
Table 1: Measured mass flow rate for stationary opening
( revolutions per minute )
Mass flow rate ( kg/h )
Figure 3 ( a ) shows the secret plan of mass flow rate at the recess and the mercantile establishment for each velocity, while the loss of mass flow rate is plotted on Figure 5 ( B ) .
( a ) ( B )
Figure 3: Measured mass flow rate ( a ) at recess and mercantile establishment, ( B ) the loss
As seen on table 1, for the slower fan velocity, i.e. 160 and 306 revolutions per minute, the loss of mass flow rate is about 2.5 aa‚¬ ” 2.6 % of recess mass flow rate, while for the fan velocity of 451, 597, 742 and 837 revolutions per minute, the loss of mass flow rate increased become 5.7, 5.8, 6, and 5.3 % of recess mass flow rate severally.
5. Analysis OF THE ROTATING ORIFICE
The consequence of revolving opening in forestalling seal escape so investigated. The opening phonograph record is rotated with the velocity of motor of 15, 20, and 25 Volt. The fan velocity is varied from 160 revolutions per minute to 887 revolutions per minute besides. Table 2 below shows the mensural mass flow rate at the recess and mercantile establishment for each fan velocity with revolving openings. The loss of mass flow rate and the per centum to the recess mass flow rate is besides shown.
Table 2: Measured mass flow rate for revolving opening
( revolutions per minute )
Orifice velocity ( V )
Mass flow rate ( kg/h )
From table 2 can be seen that with the rotary motion of opening, the recess mass flow rate for fan velocity of 160 revolutions per minute to 451 revolutions per minute has increased rather important instead than the increasing of recess mass flow rate for fan velocity of 597 revolutions per minute to 887 revolutions per minute. It can be revealed that for the lower mass flow rate, the rotary motion of openings gives consequence to draw the higher mass flow rate into the system.
The curve secret plan demoing the consequence of the rotary motion of opening to the loss mass flow rate for each fan velocity is shown on Figure 4 below.
( a ) ( B )
( degree Celsius ) ( vitamin D )
( vitamin E ) ( degree Fahrenheit )
Figure 4: The consequence of revolving orifice velocity to the loss of mass flow rate for fan velocity of ( a ) 160 revolutions per minute, ( B ) 306 revolutions per minute, ( degree Celsius ) 451 revolutions per minute, ( vitamin D ) 597 revolutions per minute, ( vitamin E ) 742 revolutions per minute, and ( degree Fahrenheit ) 887 revolutions per minute.
As observed from Figure 4 above, the loss of mass flow rate for fan velocity of 160, 306, and 451 revolutions per minute is increased with the rotary motion of opening. While for fan velocity of 597, 742, and 887 revolutions per minute, the loss of mass flow rate is decreased with the rotary motion of opening.
The incoming air largely goes to the revolving phonograph record, therefore the sum of the air through the seal will increasing, ensuing the increasing of the mass flow escape.
A trial rig has been designed and built to execute experiments on revolving radial openings. The intents of this research are look intoing the consequence of revolving openings in forestalling seal escape so comparing to the stationary openings. The trial is performed with assorted fan velocity and radial phonograph record velocity. The mass flow rate at the recess and the mercantile establishment is measured utilizing the wind gauge. The loss of mass flow rate is so calculated.
The consequence revealed that the loss of mass flow rate for the recess mass flow rate lower than 42 kg/h is increased with the rotary motion of openings. While for the recess mass flow rate greater than 55 kg/h the loss of mass flow rate is diminishing with the rotary motion of openings. Hence it can be concluded that the pumping consequence of revolving openings is effectual in forestalling seal escape at the recess mass flow rate greater than 55 kg/h. In other manus, for the recess mass flow rate lower than 42 kg/h the stationary opening give the best consequence in forestalling seal escape.