Results from the model are in reasonable agreement with the limited data available. The labyrinth is a straight through design and a defined clearance on the shaft. The gmn noncontact seal has become famous for its compact design. The axial clearance as shown in the table of dimensions means the total axial movement of both rings from one end position to the other. Find labyrinth seals and clearance seals on globalspec by specifications. Shorter deliveries are therefore possible in view of the simpler stocks 2. Straight through triangular labyrinth seals are one of the most commonly used types of noncontacting annular seals. For labyrinth seals on a rotating shaft, a very small clearance must exist between the tips of the labyrinth threads and the running surface. This can be accomplished either by reducing the clearance size, the development of a new geometrical seal configuration and the use of blowing through the seal gland. In this paper, the gambit of 3d model was adopted to divide the labyrinth gap in an unstructured approach. This study analyzed the influence of configuration and clearance on the leakage behavior of labyrinth seals. The radial deformation which decreases the clearance between the rotating and stationary. Our business is servicing our customers needs for the repair and manufacture of labyrinth seals and bearings for turbomachinery, either in.
Ornltm6373, a fluid mechanics model to estimate the. Then, the labyrinth seal was replaced with a highly stable seal not specified equipped with inlet preswirl brake. Typical clearance should be twice the maximum aggregate size of the concrete mix design. The basic concept of labyrinth seals is to reduce contaminant ingression not only by restricting the clearance through which particles enter but also by creating areas of turbulent flow to exclude contaminants. Annular seals are found to leak approximately twenty percent more than corresponding labyrinths over the entire range of realistic clearance. Please see the comparison with standard contact seals in the table below. Well fluid moving into the pump intake will be on the top of this shaft seal. The effects of clearance sizes on labyrinth brush seal leakage. Performance evaluation of trapezoidal teeth labyrinth seal authors. The steel inner ring is first surrounded with molded aluminum. Pdf turbomachinery sealing is a challenging problem due to the varying clearances caused by thermal transients, vibrations, bearing liftoff. The influences of increasing the number of teeth from 1 to 6 with step 1 and the tip clearance s0. They operate on the principle of positive clearance and. Having the edge with john crane labyrinth seal solutions seal solutions can make a big difference in the way your rotating equipment performs.
Pdf progressive clearance labyrinth seal for turbomachinery. Bearings which call for a high oil throughput are provided with seals with two labyrinth systems type 20. The experimental results prove that the effects of the circumferential turbulence make. Other system factors that affect seal leakage rates, besides condition of the seal parts, include pump operation at offdesign conditions, pipe strain, bearing problems, fitting leaks at the seal gland often mistaken as seal leakage, impeller or sleeve gasket damage, etc. The head of the seal will be bolted to the bottom of the pump intake. Optimization of labyrinth seal for screw compressor. Clearance between the shaft and labyrinth is critical. Base seal externally placed, labyrinth, and split waterstops comprise a special class of pvc waterstops and require.
Radial clearance labyrinth seal figures 1 and 2 show two arrangements of labyrinth seals in which the close running clearance is in a radial direction. The remaining 5 0% is retained by the labyrinth seals. Wide range of pressures, temperatures, and shaft speeds inexpensive. Labyrinth seal article about labyrinth seal by the free. They operate on the principle of positive clearance and do not rub on shafts or housing. Timken industrial seal technical manual high performance seals large bore assembled seals bearing isolators. The present paper investigates the effects of the trapezoidal teeth labyrinth seal on the leakage amount in gas turbines. The diametral clearance between each of the seal teeth and the rotating shaft is equivalent to a series of orifices.
Generally, springloaded lips are for retaining oil and nonspringloaded are used for low speed grease retention or excluding contaminants. Furthermore, adequate clearance should be maintained between reinforcing steel and the waterstop. On the other hand, synchronous vibration increased in amplitude, presumably due to a large. Pdf optimization of labyrinth seal for screw compressor.
Numerical simulation of leakage rates of labyrinth seal. Clearance effects on corresponding annular and labyrinth. An adjustable labyrinth seal for a steam turbine wherein the packing rings may be displaced from a larger diameter position, affording a relatively larger shaft clearance, to a smaller diameter position, affording a relatively smaller shaft clearance. In 2011, with a non rotating shaft, seal flow rate measurements with increasing inlet air temperatures to 300c show the halotm seal leaks 50% or less than the labyrinth seal. Pdf mechanical growth of labyrinth seal researchgate. In jet engines they rotor fluid interactions in stepped labyrinth seal. Labyrinth seals, formerly named leidenfrost seals or mini mace, have a very specific manufacturing process that guarantees the identity of the inner and outer ring profiles to ensure they remain inseparable here are the steps taken to produce a labyrinth seal. Disadvantages leakage depends on clearance inevitable wear enlarges clearances and worsens leakage. The end seal of the sleeve bearing serves to retain 90% of the oil vapor splashing oil in the chamber.
The teeth of the labyrinth seal may be on the rotating shaft teeth on rotor tor or on the stator tos, or both, in an interlocking configuration. This is the primary type of seal described in the skf seal handbook. Wyssmann sulzerescher wyss ltd zurich, switzerland the prediction of rotordynamic coefficients for gas seals is achieved with the aid of a twovolume bulk flow model based on turbulent rotationally symmetric 3d flow calculations including swirl. The results were compared with the simulation data of the 2d model. Oil groove clearance reference up to 50 y y y y y 0.
The difference in how competing seals perform is in. The seal operates at nominal supply and discharge pressures. Many investigators tackled the leakage problem through labyrinth seals for turbomachinery. Labyrinth seals and clearance seals specifications. Air compressors generally will always use a labyrinth seal. The diameter which corresponds to the larger of the two knifeedge diameter in a staggered labyrinth seal. Labyrinth seals that do not contact the shaft depend on a tortuous interface, fluid surface tension, and a pumplike design to prevent leakage.
Tc ratio ofseal tooth tip to clearance tipcr tip labyrinth seal tooth tip m. Results are compared to a data for teethonrotor labyrinth seals with smooth. The leakage through the seal is directly related to the labyrinth profile and also the clearance between the rotor and. There is a rotating mechanical shaft seal mech seal located in the head. The land ring forms a clearance with the knifeedges effecting the seal. It is necessary to manufacture 14 fits to get a seal with only 3 labyrinth steps and very often the mounting space of custom made labyrinth seals is very large. Cavity pressures, velocity and leakage computation in. Us5002288a positive variable clearance labyrinth seal. Labyrinth seal design optimization based on quadratic.
Ep0276839b1 ep88101192a ep88101192a ep0276839b1 ep 0276839 b1 ep0276839 b1 ep 0276839b1 ep 88101192 a ep88101192 a ep 88101192a ep 88101192 a ep88101192 a ep 88101192a ep 0276839 b1 ep0276839 b1 ep 0276839b1 authority ep european patent office prior art keywords seal seal holder housing holder axial length prior art date 19870128 legal status the legal status is an. Effects of clearance sizes on the pressure and leakage characteristics in a shaft labyrinth brush seal were numerically. A rather unexpected finding is that a dramatic increase of swirl velocity occurs near the discharge of smallclearance annular seals, which does not arise in corresponding labyrinth seals. Performance evaluation of trapezoidal teeth labyrinth seal. Labyrinth seals often use a series of noncontact metal rings or other. The effects of the main labyrinth seal parameters, such as tooth angle, sealing clearance, and cavity depth, were compared using fluent software and iterative. A theoretical model for the design of a labyrinth seal gland. The mass leak rate is shown to be proportional to the seal clearance and pressure drop in the following functional dependency. A seal is a component used in a turbomachine to reduce internal leakage of the working fluid and to increase the machines efficiency.
A ring shaped member in a labyrinth seal, which is either a straightwalled cylinder or a cylinder with axial steps. The toothed labyrinth, interrupted by a vacuum break figure 7, is the most effective. As shown in figure 1, the labyrinth seal is made up of a number of evenly spaced thin strips, sometimes called teeth or fins. Isotech of illinois inc, usa a labyrinth seal that is designed to allow for radial, axial and angular misalignment of the shaft is described. Comparative analysis of the influence of labyrinth seal configuration.
Cavity pressures, velocity and leakage computation in straight through or stepped labyrinth seals. The radial deformation which decreases the clearance between the rotating and stationary parts of sealing surface is an indication that centrifugal. Steam conduits are provided in the turbine casing communicating with the annular space between the individual packing rings and the grooves in. Discharge coefficient is also found to be a strong function of tooth clearance, pitch, reynolds number and shaft speed. The measurement and prediction of rotordynamic forces. Labyrinth seals and clearance seals are minimumleakage seals that protect machine elements from contamination through a noncontact method.
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