Showing papers on "Centrifugal fan published in 1990"

Flow in a Centrifugal Fan of the Squirrel-Cage Type

Abstract: This paper presents the results of performance measurements and detailed measurements of the mean flow field at rotor inlet and rotor exit in three squirrel cage fan configurations. The flow-field measurements were taken with a five-hole probe and yield total pressure, static pressure and the three components of velocity. Measurements were taken for two casing throat areas and for two different rotors. For each configuration the flow field was measured for flow rates below, near and above the best-efficiency point. Flow patterns are complex and there is reverse flow through the rotor blading even at the best-efficiency operating condition. Although complex, the main features of flow behaviour can be understood. They were common to all three fan configurations.Copyright © 1989 by ASME

Centrifugal fan with airfoil vanes in annular volute envelope

Abstract: A rearwardly curved centrifugal blower (10) having an annular envelope (24) around the impeller (12), so that the rotating impeller draws air in through a central inlet and forces it radially outward into the envelope and out of an annular discharge. Multiple airfoil vanes (24, 27) are positioned in the annular envelope, in two axially displaced stages. The vanes are angled to turn and diffuse airflow entering the envelope.

Flow in a Centrifugal Fan of the Squirrel-cage Type

Abstract: This paper presents the results of performance measurements and detailed measurements of the mean flow field at rotor inlet and rotor exit in three squirrel cage fan configurations. The flow-field measurements were taken with a five-hole probe and yield total pressure, static pressure and the three components of velocity. Measurements were taken for two casing throat areas and for two different rotors. For each configuration the flow field was measured for flow rates below, near and above the best-efficiency point. Flow patterns are complex and there is reverse flow through the rotor blading even at the best-efficiency operating condition. Although complex, the main features of flow behaviour can be understood. They were common to all three fan configurations.Copyright © 1989 by ASME

Centrifugal fan with variably cambered blades

Abstract: Boundary layer separation in a rearwardly skewed centrifugal impeller (14, 15) can be better controlled by designing the impeller blades with an 'S' camber, i.e., with rearward curved radially extending blades in a centrifugal blower (10). The blades have a positive camber at a radially inward region and a negative camber at a radially outward region of the blade.

DC motor driven centrifugal fan

Abstract: A centrifugal fan includes a brushless d.c. motor, an impeller mounted on the motor and a scroll on which the motor is mounted. The scroll defines the air inlet and outlet and has an outer wall curved around the impeller to define a divergent air flow path. By truncating the scroll at the outlet substantially to eliminate any flat portions on the outer wall susceptible to mechanical vibrations at frequencies excited by the d.c. motor, a noise reduction is achieved. Further noise reduction may be achieved by resiliently mounting the motor on the scroll.

System for ventilating a rail traction motor and for dynamically purifying the ventilation air

Abstract: A system for ventilating a rail traction motor and for dynamically purifying the ventilation air, the system comprising a centrifugal fan (1) having radial blades (2) surrounded by a circular housing (3) and delivering air to the motor, and dynamic filter means on the path of the air delivered by the fan. The system includes a plane sheet (4) pierced by peripheral through openings (5) forming a diffusing screen and dividing the inside volume of the circular housing into an upstream chamber (6) connected to the air inlet of the fan, and a downstream chamber (7) connected to its outlet leading to the motor, an exhaust outlet (8) for exhausting impure air, the exhaust outlet being in the form of a sector on the periphery of the upstream chamber, and a separator element (9) disposed facing the opening and forming an obstacle to deflect air streams close to the blades of the fan towards a take-up section close to the exhaust opening.

Centrifugal fan with accumulating volute

Abstract: Centrifugal blowers which maintain a substantially constant (usually ±5%) static pressure field around the circumference of the blower's impeller, notwithstanding at least one abrupt radial or axial discontinuity in the volute of the blower, e.g., due to one or more external axial and/or radial constraints in an irregularly shaped package. The blower accommodates such constraints by including discontinuities in the volute; therefore the blower takes advantage of relatively unconstrained segments of the package to have an overall large size. Notwithstanding the volute discontinuities, a substantially constant pressure field around the impeller is achieved by maintaining a specific relationship between G(Θ) and H(Θ), G(Θ) being radial extent of the volute as a function of the angular displacement Θ around the impeller's circumference and H(Θ) being the axial extent of the volute as a function of Θ, angular displacement around the volute.

A cooling fan for rotating electrical machinery

Abstract: A centrifugal fan for ventilated rotating machinery is provided having tapered fan blades (46,47) to reduce sound pressure levels generated by fan operation over a wide speed range. The tapering of the fan blades (46,47) keeps the cross-sectional area of each flow channel (51) substantially constant as the air flows radially through the fan, resulting in a less turbulent flow. Each fan blade (46,47) may include a height profile having a tapered segment (55) in which blade height decreases in proportion to increasing radial distance from the central axis (49) of the fan.

Implement for the removal of insects or the like from plants

Abstract: Implements for the removal of insects from plants are provided which dedicate an individual axial flow centrifugal fan unit to each crop row unit. The fan unit also destroys the insects so removed. The frame of the implement can be articulated and driven in such a manner so as to permit fan unit position adjustment while the fans are driven and running. In some embodiments, each fan unit is constructed with means which directs at least a portion of the exhaust of the fan to the plant row in order to further facilitate insect dislodgement and removal into the intake of the fan.

Actuator assembly for controlling inlet air flow to centrifugal fans

Abstract: An actuator and associated linkage assembly combined to multiply the force applied by the actuator in moving a flow control disk of a centrifugal fan against the air pressure generated by the fan. The actuator includes an internal spring mechanism for closing the disk against the fan air pressure. For some applications the closing force provided by the return spring may be supplemented with an auxiliary spring mechanism that is mounted for providing maximum assistance in closing the control disk, yet not prohibiting the actuator from reopening the disk.

Centrifugal fan and diffuser with accumulating volute

Abstract: A centrifugal blower (10) and volute (20) in which the radial extent of the volute is controlled to keep it substantially (e.g., ±20 %) constant up to the connection to the diffuser (22). The cross-sectional area of the volute increases linearly in the direction of impeller (10) rotation to accommodate increasing airflow volume. Airflow exits the volute and enters a diffuser which rapidly opens (increases in cross-sectional area) by increasing its radial extent. The diffuser may be attached to a source of air resistance such as a heat exchanger (26).

Low-noise impeller for centrifuge fan

Abstract: The utility model relates to a low-noise impeller for centrifuge fans, which is composed of a circular bottom plate, a circular ring plate, eight or more than eight arc-shaped blades, a shaft sleeve positioned in the center part and fastening screws, wherein, the arc-shaped blades are uniformly arranged along the periphery and are positioned between the circular bottom plate and the circular ring plate The utility model can be used for replacing the cross-shaped impeller of an ordinary centrifugal fan, and can obviously decreased the working noise of the centrifuge fan The fan noise of the 60W centrifugal fan which uses the low-noise impeller can be decreased from the original 65-75 decibel to 50 decibel, and the fan noise of the 120W centrifugal fan which uses the low-noise impeller can be decreased from the original 75-85 decibel to 55-60 decibel

An electrical rotary machine and a centrifugal fan for use in an electrical rotary machine

Abstract: An electrical rotary machine, such as an automobile alternator, has a centrifugal fan (10) which is mounted on the machine rotor (20) and draws cooling air through the machine body. Some of the fan blades (14˝) are configured to abut directly the rotor (20) thereby to inhibit substantial mixing of different streams of cooling air before they enter the fan, thereby to render the loading on the blades more uniform, and give quieter operation. The fan (10) is housed within an end shield (30) which defines an annular settling chamber (33) around the fan blades (14) and four outlet openings (34) having the effect of an acoustic low pass filter.

All-arc hollow chamfered backward wing blade for centrifugal fan

Abstract: The utility model relates to a blade of an impeller of a centrifugal ventilator, particularly an all-arc hollow chamfered backward wing type blade for the centrifugal ventilator. The utility model is a blade, the center of which has a spatial interlayer and the upper and the lower surfaces of which are in a full arc type. A reasonable chamfering angle is selected, the efficiency of the centrifugal ventilator adopting the blade can reach 85%, and the noise of the centrifugal ventilator adopting the blade is three to five decibels lower than that of other ventilators. The utility model is suitable for ventilators in various types.

Impeller for centrifugal fan

Abstract: PURPOSE: To enhance performance of a fan and realize high rigidity of an impeller by coaxially combining the predetermined number of impeller element of a cylindrical shape so as to form blade spaces each substantially enlarging from the inside toward the outside in the radial direction. CONSTITUTION: A band plate 1 is cut and raised into an almost arcuate shape by means of a press machine to form blade portions 2 at predetermined arrangement pitches. In addition, preset blade portions 2' are formed in another band plate 1'. Coaxial combination of the given number of impeller elements 10, 10' in a cylindrical shape provides blade spaces each substantially enlarging from the inside toward the outside in the radial direction. Consequently, the arrangement pitch with respect to the length of the impeller can be reduced. Therefore, performance of a fan can be enhanced, and high rigidity of the impeller can be realized. COPYRIGHT: (C)1991,JPO&Japio

Device for the ventilation of railway traction engines and for filtering the ventilation air

Abstract: The device comprises a centrifugal fan (1) with radial blades (2), surrounded by a circular envelope (3) and driving the air towards the engine, and means of dynamic filtration on the path of the air driven by the fan. It comprises a flat metal sheet (4) pierced by peripheral passage openings (5) forming a diffusing screen, dividing the interior volume in the circular envelope into an upstream chamber (6) linked to the intake of air to the fan and a downstream chamber (7) linked to the drive towards the engine, an opening (8), for removal of impure air, in the form of a segment on the circumference of the upstream chamber, and a separator element (9) arranged opposite the opening and forming an obstacle deflecting the air streams close to the blades of the fan towards a take-off section close to the removal opening. … …

Freezer and refrigerator

Abstract: PURPOSE: To expand the size of each of a cooling device or a fan with a similar space as that of a prior art and improve a freezing capability by a method wherein a centrifugal fan and a guide are disposed within a cold air duct and an air blowing outlet is positioned more downwardly than the center shaft of the fan. CONSTITUTION: A rear vertical partition wall A5 defines a cooling chamber 22 and a freezing chamber 2 and the partition wall is located more forwardly than a cooling device 4. A guide 8 is formed by each of ribs of the partition wall A5 and a forward partition wall B7, a clearance in a circumferential direction of a centrifugal fan 6 becomes maximum at an air blowing outlet port and the clearance is decreased as it goes along a circumference of the fan 6 and it has a scroll shape in which the air blowing outlet is positioned more downwardly than a rotary central shaft of the fan 6. The centrifugal fan 6 and the guide 8 are disposed more forwardly than that of the partition wall A5 so as to reduce a restriction in size toward a downward direction of the fan 6 and the guide 8. The air blowing outlet of the guide 8 is disposed more downwardly than the rotary central shaft of the fan to expand the sizes of the cooling device 4 and the fan 6 upwardly. COPYRIGHT: (C)1992,JPO&Japio

Fan having non-uniformly spaced blades

Abstract: A compact automobile fan unit includes a centrifugal fan 16 fixedly mounted on the drive shaft 17 of a motor M and having a plurality of backwardly curved blades, and a generally cup-shaped housing 18 having intake openings (18a, Fig 1C) in its end wall and discharge openings (19a-e) in its side wall and secured to a yoke 11 of the motor The curved blades are circumferentially spaced at different angular intervals such that the fan has its center of gravity located on the axis of the drive shaft With the blades thus arranged, the fan unit is capable of operating at high speeds with large capacity without generating unpleasant noise

Fan cover of centrifugal fan

Abstract: PURPOSE:To equalize the air flow at each air discharge port by installing a projection part at the scroll part of a fan cover having air discharge ports at least at right and left, in a centrifugal fan for the blowing in the radial direction, and by adjusting the flow passage area between the projection part and a blade. CONSTITUTION:On the fan cover 1 for a centrifugal fan, the air discharge ports 2 - 4 are formed at the scroll parts 7 - 12. Projection parts 15 - 17 are formed at the contact part between the scroll members. The air flow at the air discharge port 2 where a large air flow can be obtained is suppressed by adjusting the flow passage area between each projection part and a blade 31, for example by reducing the area by the projection part 15, and the air flow at the air discharge port 3 where the air flow can not be increased is increased. Further, the air flow at each air discharge port is equalized by the adjustment of each projection part. Further, the air discharge direction can be freely set by directing the terminal parts 18 - 23 of the scroll part to a desired air dis charge direction.

Geared motor unit for revolving spit mounted on a cooking oven, provided with a centrifugal fan for cooling motor and oven walls.

Abstract: A geared motor unit for cooking oven spit comprises an outlet shaft (2a) at reduced speed for fitting the spit and, on the opposite side of the sheltering box (1), a drive shaft (3a) on which the rotating wheel (3) of a centrifugal fan is mounted. The fan scroll (4) is fixed to the box (1) with axial air intake (6) and radial throw (5) to blow cooling air to the desired direction, in particular onto the oven walls and the motor itself. The fasteners of the scroll (4) are preferably so arranged to allow for an easy change of the orientation of throw (5). Furthermore there can be provided a front coupling for connecting the shaft (2a) with a spit bearing hub (2) usually disengaged by spring means, so that the hub can rotate only when the spit is connected.

Household refrigerator with cold air machine

Abstract: The utility model discloses a household refrigerator with a cold air machine, characterized in that the top end of the refrigerator is provided with the cold air machine. An electrical motor, a centrifugal fan, an air channel and a cold air machine evaporator connected in parallel with a refrigerator evaporator in the refrigeration system of the refrigerator are arranged in the cold air machine. The outer case of the cold air machine is provided with a cold air outlet. The refrigerator and the cold air machine can be used singly and can also be used simultaneously. While in tropical summer, a compressor of 180W-240W is used for a common single-door refrigerator, the cold air machine can produce cold air of 20 DEG C or so when the air temperature is 35 DEG C. Therefore, people can feel cool and comfortable. The effect of heatstroke prevention can be reached.

Stress analysis of centrifugal fan impeller by infinite element method

Abstract: This paper describes the use of 18 direction-of-force triangular shell elements for the stress analysis of impellers. With this type of elements the impeller is treated as an integral unit. Stresses developed in the backsheet, conesheet, and blades only due to centrifugal loads have been discussed

Air blasting device for vehicle air conditioning machine

Abstract: PURPOSE:To prevent intruded water from reaching a cooling wind outlet by opening a motor cooling wind inlet along the outer peripheral side wall of a scroll casing, arranging a cooling wind outlet connected to the cooling wind inlet on the upstream side of a blast, and forming the inside wall by the side wall of the scroll casing. CONSTITUTION:When a blower motor 7 is energized to rotate a centrifugal fan 8, outside air and inside air introduced respectively from each outside air and inside air introducing inlet 2, 3 are sucked into a scroll casing 4. In this case, a part of a blast enters the blower motor 7 from a cooling wind inlet 13 formed between each upper and lower case 4A, 5 of the scroll casing 4 through a cooling wind outlet 5B and a cooling pipe 9 to cool the inside of the motor forcedly. Further, water intruded from the outside air inlet 2 flows along the side wall of the scroll casing 4 by wind force, and when it reaches the cooling wind inlet 13, it drops along its side wall, and drops to the bottom face of the inlet 13, or scatters toward the side of a connecting passage 14 side between the inlet 13 and the outlet 5B by wind, drops to the bottom face of the passage and returns again into the scroll casing 4.

Cooling device of forcedly air-cooled engine

Abstract: PURPOSE:To uniformly cool a multiple cylinder engine by arranging a cooling fan made up of a centrifugal fan on a side of the engine main body in such a manner that the fan shaft becomes parallel with the crank shaft, and connecting or interlocking the fan shaft and the crank shaft by means of a power transmitting mechanism. CONSTITUTION:A cooling fan 5, which supplies cooling wind to an engine main body 1, consists of a centrifugal fan. The cooling fan 5 is arranged on a side of the engine main body 1 in such a manner that a fan shaft 6 of the cooling fan 5 becomes parallel with a crank shaft 2. In addition, the fan shaft 6 is connected to the crank shaft 2 via a power transmitting mechanism T. In other words, a driving pulley 4, which is installed on the crank shaft 2 to which a flywheel 3 is fixed, is connected or interlocked with a fan pulley 7, which is attached to the fan shaft 6, via a power transmitting belt 8. With this contrivance, it is possible to take the power out of the fly wheel 3 in order to increase the number of revolutions of the cooling fan 5. Accordingly, it becomes possible to miniaturize a cooling unit and to improve the cooling efficiency.

Moving air conditioner

Abstract: The utility model provides a moving air conditioner. The moving air conditioner is characterized in that the moving air conditioner is provided with a water mixing impeller and a water pond; the moving air conditioner utilizes the water bloom spitting onto a coiled condenser waved by the impeller to cool down and adopts a centrifugal fan to speed up the evaporation of water and to discharge outdoors; the outlet of the centrifugal fan is externally connected with a hose. The utility model has the advantages of favorable effect of refrigeration, being movable and easy popularization. The utility model can be used in common families.

Power type separating device for gas and liquid

Abstract: The utility model relates to a power type gas-liquid separating device, which is formed by that a centrifugal fan and a small gas-liquid separator are connected in parallel. A liquid discharging pipe which forms an acute angle with a gas flow direction is arranged near the outlet part of the centrifugal fan. The liquid discharging pipe is connected with the gas inlet of a cyclone separator. The gas outlet of the cyclone separator is communicated with the gas inlet of the centrifugal fan to achieve the purpose of multiple separation. The resistance when gas passes through the utility model is small. Because the rotating speed of the centrifugal fan is constant, and the effect of the gas-liquid separation is not influenced by the flow speed and the flow rate of the gas, the application field of the utility model is enlarged.

Fan and heat exchanger for a cooling system

Abstract: A centrifugal fan (20) for use with a heat exchange system has a plurality of scrolls (23) for supplying air to respective air outlets (21); for example the scrolls extend around the axis of the fan on opposite sides and the outlets are diametrically opposed. The heat exchanger (50) has respective passages (51) for a working fluid and passages for cooling air (52) and a centrifugal fan (20) providing high pressure air to the cooling air passages which are dimensioned in relation to the fan such that turbulent air flow through the cooling air passages is achieved.

Centrifugal fan having a reduced noise level

Abstract: This fan 1 consists of a stack of at least two units 2, 3 consisting of two circular concentric end flanges 6, 7 and 12, 13 joined together by blades (vanes) 11, 20 of suitable curvature arranged in parallel with respect to the flow of air, the air being sucked in by a first unit 2 and the shaft of the motor 5 being fixed to the unit 3 which is furthest away from this first suction unit

A broadband noise prediction scheme for low- noise centrifugal blowers

Abstract: In this paper we outline a semi-empirical procedure for predicting the broadband sound power spectrum radiated by any member of a family of geometrically similar, centrifugal blowers. The prediction scheme is based on the use of a normalized sound power spectrum that is obtained by measuring the sound power radiated by one member of the blower family. In the present instance, a lownoise blower design has been identified by conducting a large scale parametric study of blower noise as a function of geometrical design parameters and operating point; the resulting optimum design served to define the geometrical parameters of the blower family considered here. The prediction procedure allows calculation of either 1/3-octave band spectral levels or overall A-weighted levels. In addition it is possible to calculate "noise surfaces," i.e., plots of A-weighted sound power level versus design parameters and operating condition; in this way it is easy to identify optimally quiet blower designs that satisfy specified pumping requirements. It has been found, for example, that large diameter impellers of relatively small width operating at low speeds tend to result in the lowest noise level at a given pumping requirement. INTRODUCTION "Sound laws" can be used to predict the overallsound power level radiated by centrifugal blowers when the power level of a geometrically similar reference blower is known [1]. In this paper we present a prediction scheme for blower noise spectra that is firmly based on an existing parametric representation of blower noise spectra. In particular, it will be shown that a parameterized spectral representation proposed by Maling [2] may be combined with measured reference data to yield noise predictions for a complete family of geometrically similar blowers. In addition, Maling's approach has been extended here to allow for impeller width variations in the scaling procedure. A key result of the present work is the definition of a noise surface that allows one to identify the low-noise blower designs that will meet a given pumping requirement. DEVELOPMENT OF A NOISE PREDICTION SCHEME The scheme presented here allows the prediotion of the 1/3-octave band sound power levels in the frequency range 100 Hz to 10 kHz for various blowers having 78 Emission: Noise Sources different geometries and operating speeds, but all fulfilling a specified pumping requirement (i.e., a particular combination of pressure and flowrate). As a result, the overall A-weighted sound power level can then be calculated and plotted versus the corresponding point of rating, 1/>, and the aspect ratio, a (impeller width over diameter), to produce a noise surface. The lowest noise level can then be identified along with the corresponding blower geometry and the required operating speed. The scheme is based on measurements of the aerodynamic and acoustic performance of a low-noise reference blower that is treated as a representative member of a family of geometrically similar blowers. The aerodynamic data consist of a discrete set of operating points at which acoustical measurements were conducted using the reference blower. For each operating point, nondimensionalized generalized flow and pressure coefficients, I/>g and lj/g, were calculated according to equations (1) and (2) [2]: Q I/> g 1C D3N a' (1)