RADIAL
RADIAL
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第二组Displacement pumps are those where the volume of the pump chamber is alternately increased to draw the liquid in from the suction pipe and then decreased to force the liquid out into the delivery pipe. Centrifugal pumps are those wherein an impeller rotating at high speed throws the liquid by centrifugal force from the center to the periphery of the impeller where the liquid is discharged through the delivery outlet.Gear pump consists of two or more meshing gears (spur, single or double helical teeth) enclosed m a close-fitted housing. These are used extensively for pumping fuel oil, lubricating oil and hydraulic oil. When gears are unmeshed on the inlet side, a pressure drop occurs that helps the atmospheric pressure acting on the surface of the oil in the reservoir to force it up the pipe to fill the void, the oil is then transferred around the periphery of the pump housing. As the gear teeth mesh again on the outlet side, they form. a seal that prevents oil from backing up to the inlet, the oil in the void is then be forced out into the discharge line.All vane pumps have a rotor driven within a ring (cam ring) by a drive shaft coupled to a prime mover. A cylindrical rotor with sliding vanes, generally in radial slots, rotates within the ring. The center of the rotor is offset from the center of the ring. In a simple vane pump, as the rotor turns, the vanes are forced outward against the inner surface of the cam ring by centrifugal force. This outward radial movement of the vanes and turning of the rotor causes the chamber between the vanes to increase as the vanes pass further away from the inlet port. This increase in volume results in a lowering of pressure until the atmospheric pressure is sufficient to force oil from the reservoir into the inlet chamber. Oil from the inlet is swept away by the vanes toward the outlet port through a decreasing series of chambers until it is forced through the outlet port. A vane pump of balanced design has an elliptical cam ring so that two pumping chambers are formed. This pump is in hydraulically balance, since the two intake and two outlet ports are diametrically opposed to each other. Therefore the side loads exerted on the rotor cancel out, thereby increasing bearing lift and permitting high operating pressure.According to the last sentence of paragraph 1, from where the liquid is discharged through the delivery outlet?A.from the eye of the impellerB.from passage of impellerC.from the periphery of the impellerD.from the impeller
题干材料：Due to the large amount of heat picked up by the air in boiler and engine rooms, it would be impracticable to maintain ambient conditions within the comfort zone by air conditioning or any other means. The normal practice is to provide copious mechanical ventilation; in boiler rooms, the quantity is equated to the combustion requirements, while in a motor ship engine room the supply may be 25-50% in excess of the requirements of the engines.The axial flow fan is particularly suited to handle these large air volumes at the moderate pressures required, while of course the “straight-through” flow feature places it at an advantage over the centrifugal fan.The increasing adoption of automation, with the provision of a separate control room makes less significant the fact that comfort conditions cannot be maintained in the engine room all the time.问题：Which of the following devices should be taken to maintain ambient conditions of the boiler and machinery space?A.air compressorB.air coolerC.air-conditioning plantD.mechanical ventilation plantIn a motor vessel, the air quantity which the engine room need is_______ of the requirements of the engines.A.less than 25-50%B.more than 125-150%C.more than 25-50%D.less than 125-150%According to this passage, which of the following statements is true?A.In boiler and machinery spaces, there is the air conditioningB.In the boiler rooms the requirement of air volume should meet 25-50% of combustion requirementC.To maintain the comfort zone in the separate control room the air conditioning plant should be fittedD.The comfort conditions can be maintained in the engine room all the timeAt the middle pressure and large air quantity,_________ is more suitable.A.an axial flow fanB.a radial flow blowerC.a centrifugal fanD.an auxiliary blower请帮忙给出每个问题的正确答案和分析，谢谢！
Which davit type may be operated by one man ________．A.QuadrantalB.GravityC.Sheath-screwD.Radial
At the middle pressure and large air quantity,_________ is more suitable.A.an axial flow fanB.a radial flow blowerC.a centrifugal fanD.an auxiliary blower
以下哪些效果名称既存在于效果面板中的“Vedio EffectsTransition”特效组，又存在于效果面板中的“Vedio TransitionsWipe”特效组中？（）A、Gradient WipeB、Linear WipeC、Radial WipeD、Clock Wipe
相对于Adobe Photoshop CS，下面的模糊方式中，哪个是After Effects 6.0的模糊（Blur）方式所特有的：（）A、Channel BlurB、Directional BlurC、Gaussian BlurD、Radial Blur
单选题What is the name of the movable，radial guide line used to measure direction on a radar?（）ACompass roseBCursorCPlan position indicatorDVariable range marker
单选题A multistage centrifugal pump can be BEST described as having （）.Atwo or more impellers housed together in one casing and mounted on a single shaftBa single stepped impeller mounted in a progressively staged casingCa large radial clearance between the impeller and casing to prevent overheating due toDan increase in the discharge velocity of the liquid with a corresponding decrease in pressure through the stages
单选题If a radial piston hydraulic pump fails to deliver rated fluid volume, the cause can be （）.Acontaminated fluidBpitted thrust ringsCworn pintle bearingsDobstructed suctions passage
单选题Which features of a centrifugal pump reduce the need for renewing worn impellers and pump casings?（）AClose radial clearance between impeller hub and casingBLow rotational speed of impellerCRemovable end plateDReplaceable impeller and casing wearing rings
单选题To thoroughly pump out the bilges using a horizontally mounted centrifugal pump, the （）.Apump must always be primedBvolute must impart a radial and rotary motion of the water suction sideCconnection must guide the liquid to the lantern ringsDstuffing box should not be allowed any water leakage
单选题Which statement is TRUE concerning lifeboat gripes?（）AThey must be released by freeing a safety shackleBThey should not be released until the boat is in lowering positionCThey may be adjusted by a turnbuckleDThey are normally used only with radial davits
单选题Which of the following statements is/are true regarding hydraulic pumps in general? （）AVariable volumes can be obtained with gear pumps only by variation of the pump drive speedBA radial piston pump houses sliding pistons in a stationary cylinder block through which passes a rotating pintle or ported shaftCThe amount of fluid displaced per revolution of an axial piston rotary pump is dependent on the angle formed between the cylinder block and valve plateDAll of the above
单选题A butterfly valve consists basically of a disc pivoted across the bore of a ring body having the same radial dimensions as the pipe in which it is fitted.According to the above sentence, which of the following statements is not true?（）AThe diameter of a disc is the same as the outer diameter of the pipeBWe can infer that the valve is opened or closed by rotating the spindleCA butterfly valve comprises a disc and a ring bodyDThe profile of the butterfly valve is a ring body
单选题An axial轴向 piston pump differs from a radial piston pump as the pistons of an axial piston pump are positioned （）.Aradially from the shaftBparallel to each other and to the shaftCparallel to each other but at a right angle to the shaftDat an angle to each other and to the shaft
单选题In a radial piston pump, reversal and control of fluid flow are accomplished by moving the （）.Acentral valveBradial plungerCfloating ringDcylinder body
单选题With reference to a radial piston pump, which one of the following statements is false?（）ASurrounding the fixed shaft is a hollow shaftBThis hollow shaft carries radial boresCEach bore is fitted with a well-lapped plungerDThere are always even numbers of bores
单选题What is TRUE concerning frapping lines?（）AThey are used to steady a lifeboat when loweredBThey are normally attached to the davit spanCThey are needed only on radial davitsDThey are used to clear the puddings
单选题Which of the following actions should be taken if during a routine maintenance inspection of a centrifugal pump, localized scoring on a pump shaft sleeve is detected?（）ACorrect the cause of the scoring and repair the sleeve or replace with a new oneBReassemble the unit and provide more water leak off for proper lubricationCCheck for parallel alignment of the sleeve radial faces to the sleeve boresDReassemble the unit and adjust the governor to obtain a slower speed
名词解释题RADIAL