In this invention a suitable fluid-for example, a highly heat-conductive and low-melting-point molten metal-1s hermetically sealed in a channel that passes near to the surfaces of the rotor. When the fluid is heated by hot gas on the turbine side of the rotor, the fluid expands; consequently, its density drops. This drop in density causes the hot fluid to flow radially inwardly on the side next to the turbine surface, being displaced by the heavier cooler fluid that flows radially outwardly on the side next to the compressor surface. Thus, forced thermal circulation of' the fluid conducts heat away from the turbine side of the rotor to the compressor side of the rotor. The cooling action of the circulating fluid supplements and has a greater heat-carrying capacity than the solid metal core of the rotor disc. By having the channels for the circulating fluid strategically located, e.
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Centrifugal compressors are the dynamic type, meaning that compression is accomplished through the conversion of kinetic energy to static energy. The defining characteristic of centrifugal compressors is that head is determined by the volume flow through the unit.
In the case of an axial-inlet centrifugal compressor typical of integrally geared units , an appropriate length of pipe serves to smooth the flow of gas into the eye of the first impeller. The impeller spins on a shaft and is the means by which energy work is imparted on the gas. Additionally the gas encounters rotating blades in the impeller. These blades push the gas in a circular motion resulting in a static pressure rise compression due to the centrifugal force of rotation.
For the impeller with the typical backward-leaning blade, approximately two thirds of total static pressure rise of the stage is obtained within the impeller. Upon leaving the impeller, the flow has two velocity components: the first is a component in the radial direction, VR, and the second is a component in the tangential direction, VT impeller velocity components. The high velocity gas then enters the diffuser. The diffuser is a stationary component which primarily converts velocity kinetic energy to pressure static energy.
The diffuser is a radial passage that is roughly the same width as the impeller blade, but the radial area expands and provides the desired diffusing effect. As the gas exits the diffuser and enters the return bend, the gas has obtained the majority of the static pressure rise for the centrifugal stage a centrifugal stage being the combination of the impeller and diffuser. The shape of the head versus flow curve is very much a characteristic of the impeller geometry Head vs.
For the typical compressor stage, decreasing the required head increases the volumetric flow. Likewise, increasing the required head reduces the volumetric flow. The ends of the curve are defined by surge at the low-flow end and stonewall at the high-flow end.
The power vs. For a given stage, the shape of the power curve is a function of flow, head, and efficiency Power versus Flow. With respect to controlling operational range, the order of effectiveness is typically as follows:.
An additional downside is the potential increase in after-cooler size if the recycle flow is large. The operational map for the compressor is usually limited by mechanical constraints, such as rotor dynamics or impeller stress. This is a very efficient means of compressor control, however the effect can be limited when there are many stages of compression.
Throttling can also be applied at the discharge of the compressor. Turbomachinery Blog features postings from experts in all areas of turbomachinery, such as: gas turbines, machine diagnostics, materials, repairs, and aftermarket parts, and encourages users to participate, with reader engagement and interaction as its primary purpose.
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Variable Inlet Guide Vanes Boost Centrifugal Air Compressor Efficiency
Principle of operation : Air is sucked into the impeller eye and whirled outwards at high speed by the impeller disk. At any point in the flow of air through the impeller the centripetal acceleration is obtained by a pressure head so that the static pressure of the air increases from the eye to the tip of the impeller. The remainder of the static pressure rise is obtained in the diffuser, where the very high velocity of air leaving the impeller tip is reduced to almost the velocity with which the air enters the impeller eye. Usually, about half of the total pressure rise occurs in the impeller and the other half in the diffuser. Owing to the action of the vanes in carrying the air around with the impeller, there is a slightly higher static pressure on the forward side of the vane than on the trailing face. The air will thus tend to flow around the edge of the vanes in the clearing space between the impeller and the casing.
Centrifugal compressors are the dynamic type, meaning that compression is accomplished through the conversion of kinetic energy to static energy. The defining characteristic of centrifugal compressors is that head is determined by the volume flow through the unit. In the case of an axial-inlet centrifugal compressor typical of integrally geared units , an appropriate length of pipe serves to smooth the flow of gas into the eye of the first impeller. The impeller spins on a shaft and is the means by which energy work is imparted on the gas.
US4054398A - Centrifugal compressor or centripetal turbine - Google Patents
The following interview describes how centrifugal compressor efficiency can be improved thanks to recent developments in IGV technology. CABP: Many of our readers own and operate centrifugal compressors, and they frequently ask about how to reduce their energy consumption. CAGI: Absolutely, and energy conservation should be first on their minds. Frequently, equipment cost is the major decision factor, but energy consumption represents approximately 82 percent of the product life-cycle cost.
Centrifugal compressors: Basics and operational range
The invention relates to a centrifugal compressor and is particularly concerned with a diffuser therefor. The invention is also applicable to a centripetal turbine and to a nozzle assembly therefor. The diffuser and nozzle assembly are herein referred to generically as "a working fluid guidance assembly" and the centrifugal compressor and centripetal turbine are herein referred to generically as "a radial flow turbo-machine". One object of the invention is to provide a light-weight working fluid guidance assembly, as hereinbefore defined, which is also cheap and quick to manufacture. Another object of the invention is to provide a working fluid guidance assembly, as hereinbefore defined, which is of adjustable or variable geometry. According to the invention, a working fluid guidance assembly, as hereinbefore defined, comprises a pair of axially spaced walls defining an annular housing open at its inner and outer peripheries and a plurality of vanes extending between the walls and defining therewith, between adjacent vanes, working fluid passages open to the inner and outer peripheries of the housing, each vane comprising a pair of partitions having a common edge extending between the housing walls adjacent the inner periphery of the housing and being spaced apart circumferentially at positions remote from the inner periphery of the housing. At least one of the partitions of each pair may be adjustable toward or away from the adjacent partition of an adjacent pair of partitions.