This work is licensed under a Creative Commons Attribution 4. Skip to main content Skip to main navigation menu Skip to site footer. Rumaherang Abstract An Important problem in centrifugal pumps designing is characteristic works in theoretical calculations. They are precise or very close to practical characteristics and results of tests in laboratory. Hydrodynamics parameters influence on the inlet sides, blades of impeller, vaned diffusers, stage guide vanes and side go out of pump.

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Please scroll down to see the full text. Download details: IP Address: Albraik, F. Althobiani, F. Gu and A. Pumps are the largest single consumer of power in industry. This means that faulty pumps cause a high rate of energy loss with associated performance degradation, high vibration levels and significant noise radiation.

This paper investigates the correlations between pump performance parameters including head, flow rate and energy consumption and surface vibration for the purpose of both pump condition monitoring and performance assessment. Using an in-house pump system, a number of experiments have been carried out on a centrifugal pump system using five impellers: one in good condition and four others with different defects, and at different flow rates for the comparison purposes.

The results have shown that each defective impeller performance curve showing flow, head, efficiency and NPSH Net Positive Suction Head is different from the benchmark curve showing the performance of the impeller in good condition.

The exterior vibration responses were investigated to extract several key features to represent the healthy pump condition, pump operating condition and pump energy consumption. In combination, these parameter allow an optimal decision for pump overhaul to be made [1].

Keywords: Variable speed pump, pump performance, centrifugal pump 1. Introduction The current methods for monitoring simple vibration analysis are not adequate enough to predict incipient faults in a pump and avoid frequent breakdowns and outages that are causing the shutdown of large pumps. The condition of components such as pump shafts and impellers, roller bearings and drive parts is monitored by evaluation of specific machine vibrations, vibrations due to flow excitation, and structure borne sound in roller bearings.

The examination also involves operating parameters such as the flow rate, suction pressure, output pressure, drive power, speed, bearing temperatures and leakage monitoring. Condition information is automatically transmitted to the system [2]. Vibration sources of a centrifugal pump 2. The mechanical sources are invariably generated by rotation of unbalanced masses and friction in the bearings. The generated vibration will cause the pump surface to vibrate which will then act as a loudspeaker radiating airborne noise.

Thus the basic mechanisms generating both structure borne vibration and airborne noise are the same. Chudina et. The broadband content is ascribed to flow turbulence and vortex shedding particularly in the narrow spaces between the pump rotor and adjacent stationary parts of the casing.

There will also be a contribution from such mechanical sources as the rotation of the pump shaft and bearings. Turbulent noise will be at a minimum when the pump works with maximum efficiency, i.

Off-design flow rates generate additional hydraulic noise, particularly for very low flow rates when internal recirculation occurs between the suction and discharge areas of the pump. When the flow rate is greater than the design flow rate, flow turbulence and boundary layer vortex shedding both increase [6,7]. The discrete components in the pump spectrum are primarily due to interaction of the rotor blades with adjacent stationary objects e.

At or near the design point flow turbulence is at a minimum so the discrete components, particularly the lower harmonics, tend to dominate the spectrum [8]. Away from the design point the turbulent noise will increase and will, eventually, even exceed the tonal noise [5,7]. As the mechanical condition of the machine changes because of wear, changes in operating environment, load variations etc. The vibration profile that results from motion is the result of a force imbalance — there is always some imbalance in real-world applications [9].

Causes of vibrations are of major concerns because of the damage to the pump and piping that generally results from excessive vibration. Excessive vibration in a pump may be a result of improper installation or maintenance, incorrect application or hydraulic interconnections with the piping system [10]. Vibration can be defined as simply the cyclic or oscillating motion of a machine or machine component from its position of rest. Forces generated within the machine cause vibration.

These forces may: 1. Change in direction with time, such as the force generated by a rotating imbalance. Change in amplitude or intensity with time, such as the unbalanced magnetic forces generated in an induction motor due to an unequal air gap between the motor armature and stator.

Result in friction between rotating and stationary machine components in much the same way that friction from a bow causes a violin string to vibrate. Result from impacts, such as the impacts generated by the rolling elements of a bearing passing over flaws in the bearing raceways. Result from randomly generated forces such as flow turbulence in fluid-handling devices such as fans, blowers and pumps; or combustion turbulence in gas turbines or boilers [11].

When the internal pressure in a fluid reaches its vapour pressure, cavities form in the low-pressure regions, these collapse when they reach a place of higher pressure in the pumping system. This phenomenon takes place in a short time in a working centrifugal pump [12,13,14]. Cavitation can also cause pump vibration. Indications of a cavitating pump can include noise, fluctuating flow rates, a decrease in discharge pressure, and vibration.

The components that commonly fail prematurely are impellers, wear rings and casings. Cavitation does not always produce pump vibration, and the induced vibration often is random and unmeasurable [15]. One of the other causes of flow-induced vibration at blade passing frequencies in centrifugal diffuser pumps is the inappropriate radial gap between impeller and volute vanes. A small gap may be preferable for pump performance, head and efficiency.

With wear, operational records will indicate a gradual change in performance over some period of time. Partially blocked pathways will usually be evidenced by a pump that delivers full discharge pressure at shut-off, with a sharp drop in discharge pressure as flow is increased.

The drop in discharge pressure is often accompanied by increased vibration as the flow restriction starts to cause cavitation. If vibration is also present at shut-off the blockage may be in the impeller causing a physical imbalance [17]. Rotating stall is a flow instability occurring in most type of centrifugal pumps when the flow rate is reduced below the design value. Aside from the mechanical vibrations which can be induced by stall, the generated acoustic noise can also be an important problem [18].

Resonance conditions can cause excessive vibration levels, which in turn are potentially harmful to equipment and environment. Pumps, their support structure, and piping are subject to a variety of potential structural vibration problems resonance conditions. Fixed-speed applications often miss these potential resonance situations because the common excitation harmonics due to running speed, vane passing frequency, plunger frequency, etc.

For variable speed drive applications, the excitation frequencies become variable and the likelihood of encountering a resonance condition within the continuous operating speed range is greatly increased.

Pump vibration problems typically occur with bearing housings and the support structure base plate for horizontal applications, motor and stool for vertical applications [19].

Test rig measurements The test rig consists of a centrifugal pump, variable speed motor and the closed-loop water piping system for water circulation. A photograph of the finished test-rig is shown in figure 3. The centrifugal pump was used in the test-rig shown in Fig. It is driven by a three-phase electric motor running at rpm on 9. The capacity of the tank is based on the maximum flow rate. Figure 3. Photograph of the test-rig. The test-rig pump. Table 3.



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Kavitasi adalah salah satu indikator penting kondisi operasi sebuah pompa sentrifugal. Fenomena kavitasi ditunjukkan dengan terbentuknya formasi gelembung udara yang kemudian pecah secara tiba-tiba akibat perubahan tekanan pada sisi hisap pompa. Kavitasi dapat menyebabkan kerusakan yang parah komponen pompa terutama bagian sudu atau impeller. Kavitasi biasanya dapat diidentifikasi melalui suara bising dan timbulnya getaran yang berlebihan. Sebuah metode deteksi kavitasi dibutuhkan agar potensi kerusakan lebih lanjut pada pompa sentrifugal dapat diantisipasi secepatnya. Penelitian ini bertujuan menghasilkan sebuah metode deteksi kavitasi menggunakan spektrum getaran dan spektrum envelope pada bentang frekwensi rendah kHz dan bentang frekwensi tinggi ,5 kHz.


Analisa Simulasi Kerusakan Impeller pada Pompa Sentrifugal Akibat Kavitasi

Centrifugal pumps are widely used equipment in a variety of industrial applications and some other sectors. The pump works by converting mechanical energy into kinetic energy or press. Pressure at the pump increases at low pressure lower than atmospheric pressure. XXX in Karawang. The analysis was performed on the centrifugal pump to calculate the speed of the suction pipe, the speed of the compressive pipe and calculate the Net Positive Suction Head NPSH to determine whether the pump worked by cavitation and analyze the speed with the Solidworks sofwar simulation.

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