Numerical and experimental investigation of flow phenomena in rotating step-holes for direct-spray-cooled electric motors

2020 ◽  
pp. 146808742091804
Author(s):  
Christopher Beck ◽  
Jürgen Schorr ◽  
Harald Echtle ◽  
Jasmin Verhagen ◽  
Annette Jooss ◽  
...  
Keyword(s):  
Flow Rate ◽  
Electric Motor ◽  
Rotational Speed ◽  
High Speed ◽  
High Efficiency ◽  
Volumetric Flow Rate ◽  
Dielectric Fluid ◽  
Electric Motors ◽  
Test Environment ◽  
Operating Points

Despite their high efficiency, electric motors are thermally limited in some operating points by several types of losses. Whenever temperature–critical components threaten to overheat, the performance is reduced for component protection (derating). The use of a suitable cooling concept may reduce the derating. The design of efficient cooling concepts of electric motors in traction drives with increased power densities is challenging, caused by the fact that the heat releases in the components vary considerably with the operating point. One option to reduce the temperatures is to place the heat sinks close to heat sources. Therefore, direct spray cooling with nozzles located in the rotor shaft is often used for cooling the end windings. The dielectric fluid (e.g. oil) is introduced into the mainly air-filled interior of the electric motor. In the following study, the behavior of the jet in the rotating step-holes at different volumetric flow rates is examined. To carry out the investigation, a new test rig and a novel optically accessible electric motor were designed. In this specifically designed test environment, the shape of the jets of different operating points is investigated by direct high-speed visualization. The cinematography setup is made of a four-light-emitting diode system in combination with a high-speed camera. A combined approach of experiment and simulation is used to find basic mechanisms of spray formation produced by rotating step-holes. Depending on the volumetric flow rate and the rotational speed, the direction of the oil jet gets more curved in relation to the rotating nozzle after exiting the small bore. If the deflection is large, the jet impinges on the wall of the large bore before reaching the end of the nozzle. The jet formation at the exit of the step-hole is mainly driven by the divergent forces in the liquid caused by impingement and the counteracting Coriolis force. Depending on the volumetric flow rate with constant rotational speed, different cross-sectional shapes of the jet at the exit are observed. These characteristic shapes can be grouped as a round undisturbed jet, strands with a connecting lamella and a C-shaped cross-section.

Noise Reduction Measures for an Axial Fan

2017 ◽  
Author(s):  
Andreas Swienty ◽  
Evgenii Palamarchuk ◽  
Raja Abou Ackl ◽  
Paul Uwe Thamsen
Keyword(s):  
Noise Reduction ◽  
Flow Rate ◽  
Electric Motor ◽  
Volumetric Flow Rate ◽  
Test Stand ◽  
Pressure Increase ◽  
Operating Point ◽  
Second Phase ◽  
Characteristic Curves ◽  
Irregular Arrangement

The aim of this work is to investigate how a reduction of the noise emissions can be achieved by means of an irregular arrangement of the blades of the fan impeller and an additional blade skewing. For this purpose a fan impeller with a defined operating point is designed. Preliminary investigations have shown that a volumetric flow rate of 18 m3/h at a pressure of 200 Pa is required for cooling. Due to structural restrictions, only one axial impeller with a diameter of 68 mm can be used. The rotational speed of the electric motor is 10000 rpm. In a further step, the influences of the blade skewing and irregular arrangement of the blades are examined. These impellers are manufactured in a rapid prototyping process, which is a cost-effective and fast process. Thus, various variants can be examined to find the most suitable impeller. The study of the impellers is divided into two phases. Firstly, the fluid mechanical data of the impeller is measured. For this purpose, a chamber test stand is used to measure the characteristic curves of fan impellers. Thus, on the one hand, it can be examined whether the designed impeller reaches the operating point and, on the other hand, the influence of the noise reduction measures on the characteristic curves can also be evaluated. It is, of course, not desired that the noise reduction measures result in a deterioration of the pressure increase or in the volumetric flow rate. In the second phase, the noise generation of the impeller is measured in an installed state on an acoustic test stand. For this purpose, the impellers are installed in the electric motor and then acoustically examined in enveloping surface method according to DIN 45635. It can be seen that the sound load can be reduced by 5.6 dB by a sufficient design of the impeller compared to a reference impeller. The further measures taken, such as the irregular arrangement of the blades and the blade skewing, have shown a further improvement of 1.6 dB. The influence of the implemented measures on the characteristic curve lies in a small area. It is measured that the pressure increase has fallen due to the irregular arrangement of the blades and the blade skewing by 10 Pa with a constant remaining flow rate.

Experimental Investigation of Oil Flowrate in a Hermetic Reciprocating Compressor

2014 ◽  
Author(s):  
Sibel Tas ◽  
Sertac Cadirci ◽  
Hasan Gunes ◽  
Kemal Sarioglu ◽  
Husnu Kerpicci
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
High Speed ◽  
Operating Conditions ◽  
Lubricating Oil ◽  
Reciprocating Compressor ◽  
Oil Flow ◽  
Oil Flow Visualization

The aim of this experimental study is to investigate the mass flow rate of the lubricating oil in a hermetic reciprocating compressor. Essential parameters affecting the performance of the lubrication are the rotational speed of the crankshaft, the viscosity of the oil, the operating temperature and the submersion depth of the crankshaft. An experimental setup was built as to measure the oil mass flow rate with respect to the oil temperature variation during different operating conditions. The influence of the governing parameters such as the rotational speed, temperature (viscosity) and the submersion depth on the mass flow rate from crankshaft outlet are studied in detail. In addition, the oil flow visualization from the upper hole of the crankshaft is performed using a high-speed camera in order to observe the effectiveness of the lubrication of the various parts of the compressor. This study reveals that with increasing rotational speed, the submersion depth of the crankshaft and with decreasing viscosity of the lubricant, the mass flow rate from the crankshaft increases.

Analysis and Measurement of Effective Flow-Rate in Flood Grinding

2009 ◽  
Vol 626-627 ◽  
pp. 159-164 ◽  
Author(s):  
Chang He Li ◽  
Ya Li Hou ◽  
Yu Cheng Ding ◽  
Bing Heng Lu
Keyword(s):  
Boundary Layer ◽  
Flow Rate ◽  
High Speed ◽  
Good Description ◽  
Volumetric Flow Rate ◽  
Grinding Wheel ◽  
Work Surface ◽  
Grinding Fluid ◽  
Grinding Conditions ◽  
Grinding Machine

In the grinding process, grinding fluid is delivered for the purposes of chip flushing, cooling, lubrication and chemical protection of work surface. Due to high speed rotating grinding wheel, the boundary layer of air around the grinding wheel restricts most of the grinding fluid away from the grinding zone. Hence, conventional method of delivering grinding fluid that flood delivery is not believed to fully penetrate this boundary layer and, thus, the majority of the grinding fluid is deflected away from the grinding zone. The flood grinding typically delivers large volumes of grinding fluid was ineffective, especially under high speed grinding conditions. In the paper, a theoretical model is presented for flow of grinding fluid through the grinding zone. The model shows that the flow rate through the contact zone between the wheel and the work surface depends on wheel porosity and wheel speed as well as depends on nozzle volumetric flow rate and fluid jet velocity. Furthermore, the model was tested by a surface grinding machine in order to correlate between experiment and theory. Consequently, the effective flow-rate model was found to give a good description of the experimental results and the model can well forecast the effective flow-rate in flood delivery grinding.

scholarly journals Development of High-Efficiency, High-Speed and High-Pressure Ambient Temperature Filling System Using Pulse Volume Measurement

2019 ◽  
Vol 9 (12) ◽  
pp. 2491
Author(s):  
SeBu Oh ◽  
SeHoon Oh ◽  
ByeongRo Min
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
High Speed ◽  
High Efficiency ◽  
Response Speed ◽  
Volume Measurement ◽  
Economic Feasibility ◽  
Industrial Sectors ◽  
Filling System ◽  
Filling Time

Adjusting the filling pressure is essential to fit the final gas volume when charging a carbonated beverage with high pressure. However, in the previous mechanical carbonated ambient filling system, it was difficult to control and monitor the charging conditions such as pressure, temperature and flow rate. In this study, we have developed a high efficiency carbonated ambient filling system capable of high speed and high pressure filling, by using a pulse type electronic flow-meter. The response speed characteristics of the M(BC) and F(MH) series valves were investigated. LMS Imagine.Lab Amesim (Siemens PLM Software) was used to calculate the charging and discharging time of the system under a high CO2 gas pressure condition. The quantitative and precise charging system was implemented with the change of filling time and monitoring/controlling/correction of flow rate. Moreover, a dual controller of the high-speed pulse output was established and a high-speed data processing/flow rate charging algorithm was applied in the system. The filling variation of the system was in the range of ±3 gram(gr) (standard deviation 0.57). The developed system could be applied to improve the quality of goods and economic feasibility at various industrial sectors.

Deviations Due to Non-Newtonian Influences Within a Miniature Viscous Disk Pump

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Phil Ligrani ◽  
Hui Jiang ◽  
Benjamin Lund ◽  
Jae Sik Jin
Keyword(s):  
Newtonian Fluid ◽  
Flow Rate ◽  
Rotational Speed ◽  
Stokes Equations ◽  
Sucrose Concentration ◽  
Pure Water ◽  
Pressure Rise ◽  
Volumetric Flow Rate ◽  
Newtonian Flow ◽  
Newtonian Behavior

A miniature viscous disk pump (VDP) is utilized to characterize and quantify non-Newtonian fluid deviations due to non-Newtonian influences relative to Newtonian flow behavior. Such deviations from Newtonian behavior are induced by adding different concentrations of sucrose to purified water, with increasing non-Newtonian characteristics as sucrose concentration increases from 0% (pure water) to 10% by mass. The VDP consists of a 10.16 mm diameter disk that rotates above a C-shaped channel with inner and outer radii of 1.19 mm, and 2.38 mm, respectively, and a channel depth of 200 μm. Fluid inlet and outlet ports are located at the ends of the C-shaped channel. Within the present study, experimental data are given for rotational speeds of 1200–2500 rpm, fluid viscosities of 0.001–0.00134 Pa s, pressure rises of 0–220 Pa, and flow rates up to approximately 0.00000005 m3/s. The theory of Flumerfelt is modified and adapted for application to the present VDP environment. Included is a new development of expressions for dimensionless volumetric flow rate, and normalized local circumferential velocity for Newtonian and non-Newtonian fluid flows. To quantify deviations due to the magnitude non-Newtonian flow influences, a new pressure rise parameter is employed, which represents the dimensional pressure rise change at a particular flow rate and sucrose concentration, as the flow changes from Newtonian to non-Newtonian behavior. For 5% and 10% sucrose solutions at rotational speeds of 1200–2500 rpm, this parameter increases as the disk dimensional rotational speed increases and as the volumetric flow rate decreases. Associated magnitudes of the pressure difference parameter show that the fluid with the larger sucrose concentration (by mass) produces significantly larger differences between Newtonian and non-Newtonian fluid flow, for each value of dimensional volumetric flow rate. For each disc rotational speed, compared to Newtonian data, dimensional pressure rise variations with dimensional volumetric flow rate, which are associated with the non-Newtonian data, are generally lower when compared at a particular volumetric flow rate. Agreement with analytic results, for any given flow rate, rotational speed, and flow passage height, validates the shear stress model employed to represent non-Newtonian behavior, as well as the analytic equations and tools (based upon the Navier–Stokes equations) which are employed to predict measured behavior over the investigated range of experimental conditions.

Contribution to the analysis of liquid macroflow in a cylindrical vessel with a high speed impeller

1981 ◽  
Vol 46 (4) ◽  
pp. 963-974 ◽  
Author(s):  
Jaroslav Medek ◽  
Ivan Fořt
Keyword(s):  
Flow Rate ◽  
Inclination Angle ◽  
Turbulent Diffusion ◽  
High Speed ◽  
Volumetric Flow Rate ◽  
Cylindrical Vessel ◽  
Lower Edge ◽  
Blade Number

In hitherto published studies the investigation of liquid macroflow in a vessel with an impeller has been concentrated mostly on the assessment of the volumetric flow rate through the impeller. Due to molecular and turbulent diffusion, however, significant exchange of mass and momentum occurs between this flow and the neighbouring charge. The extent of this induced volumetric flow rate has not been systematically investigated. This contribution attempts at the assessment of the induced, and total volumetric flow rate components in a vessel, in the plane of rotation of the lower edge of an impeller with flat inclined blades, in dependence on the blade number and the inclination angle between the blade and this plane.

Flow of Granular Material through Rotating Cylinders: Modelling Transients

2000 ◽  
Vol 627 ◽  
Author(s):  
Richard J. Spurling ◽  
John F. Davidson ◽  
David M. Scott
Keyword(s):  
Steady State ◽  
Granular Material ◽  
Dynamic Model ◽  
Solid Body ◽  
Flow Rate ◽  
Rotational Speed ◽  
Transport Model ◽  
Volumetric Flow Rate ◽  
Body Motion ◽  
Angle Of Repose

ABSTRACTGranular material, fed continuously into the top of a slowly rotating, slightly inclined cylinder, forms a moving bed. Much of the bed rotates with the cylinder in solid body motion. When particles reach the surface of the bed, they move rapidly down it, and are absorbed once more into the solid body motion. Such cylinders are used in calcining, pharmaceutical manufacture, and drying. A steady state transport model, applicable when the bed depth varies slowly along the cylinder, has existed for around 50 years. The bed surface is considered locally flat, and particles in it fall along the line of steepest descent, inclined to the horizontal at the angle of repose. There is reasonable agreement with experiment.We propose a quasi-steady state dynamical model, in which the steady state model is coupled with a volume balance across an axial element. The model takes the form of a nonlinear diffusion equation which was solved numerically. The parameters of the dynamic model are the dimensions of the cylinder and outlet dam, the inclination of the axis of the cylinder, its rotational speed, the angle of repose of the granular material and its feed volumetric flow rate: the dynamic model has no free parameters. Experiments were conducted using sand, mean particle size 490 μm, in a perspex tube of length 1 m, radius 0.0515 m, lined with sandpaper, with a feed end dam of height 0.029 m, and with no exit dam, or an exit dam of height 0.0105 m. With the system initially in steady state, step changes in feed flow rate, rotational speed or axis inclination were imposed, and the resulting discharge flow rate and bed depth axial profile measured as functions of time. Good agreement is found between model and experiment.

Miniature Single-Disk Viscous Pump (Single-DVP), Performance Characterization

2005 ◽  
Vol 128 (3) ◽  
pp. 602-610 ◽  
Author(s):  
Danny Blanchard ◽  
Phil Ligrani ◽  
Bruce Gale
Keyword(s):  
Flow Rate ◽  
Rotational Speed ◽  
Pressure Rise ◽  
Volumetric Flow Rate ◽  
Outer Radius ◽  
Fluid Viscosity ◽  
Pump Chamber ◽  
Inner Radius ◽  
Viscous Pump ◽  
Single Disk

The development and testing of a rotating single-disk viscous pump are described. This pump consists of a 10.16mm diameter spinning disk, and a pump chamber, which are separated by a small gap that forms the fluid passage. The walls of the pump chamber form a C-shaped channel with an inner radius of 1.19mm, an outer radius of 2.38mm, and a depth of 40, 73, 117, or 246μm. Fluid inlet and outlet ports are located at the ends of the C-shaped channel. Experimental flow rate and pressure rise data are obtained for rotational speeds from 100to5000rpm, fluid chamber heights from 40to246μm, flow rates from 0to4.75ml∕min, pressure rises from 0to31.1kPa, and fluid viscosities from 1to62mPas. An analytical expression for the net flow rate and pressure rise, as dependent on the fluid chamber geometry, disk rotational speed, and fluid viscosity, is derived and found to agree with the experimental data. The flow rate and pressure rise of the pump vary nearly linearly with rotational speed. The volumetric flow rate does not change significantly with changes in fluid viscosity for the same rotational speed and pumping circuit. Advantages of the disk pumps include simplicity, ease of manufacture, ability to produce continuous flow with a flow rate that does not vary significantly in time, and ability to pump biological samples without significant alteration or destruction of cells, protein suspension, or other delicate matter.

scholarly journals POSSIBLE HYBRID PROPULSION CONFIGURATION FOR TRANSPORT JET AIRCRAFT

Aviation ◽  
2016 ◽  
Vol 20 (3) ◽  
pp. 145-154 ◽  
Author(s):  
Sergio CHIESA ◽  
Marco FIORITI ◽  
Roberta FUSARO
Keyword(s):  
Electric Motor ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Preliminary Design ◽  
Combustion Engines ◽  
Jet Engines ◽  
Electric Motors ◽  
Hybrid Propulsion ◽  
Air Turbine ◽  
Innovative Solution

This research is aimed at studying the possible advantages of installing, for a hybrid propulsion aircraft, electric motors and related propellers into the dedicated supplementary nacelles. This innovative solution is different from the configuration, already studied for a regional turboprop (Chiesa et al.2013), in which the electric motors are in the same nacelles of the internal combustion engines. As it has been expected, it offers the advantages of avoiding mechanical links between the two units and, more importantly, can also be applied to jet aircraft. In fact, the main contribution of electric motors is expected during ground operations, take-off and descent phases (i.e. at low speed), in which it can be useful to integrate the propellers or even substitute the jet engines with them. At high speed, the propellers, of course, are configured in order to reduce drag. When considering the design of a new airliner concept, a preliminary design study is necessary to optimize the location of the supplementary nacelles. The nacelles, which only hold the electrical motor, can also be considered retractable, as is usual for a RAT (Ram Air Turbine). Please note that in the hybrid propulsion context, the RAT function can be clearly allocated to the electric motor, with the advantages of optimizing drag at high speed, taking into account installation problems.

Design of a Centrifugal Compressor With Low Specific Speed for Automotive Fuel Cell

2008 ◽  
Author(s):  
Xinqian Zheng ◽  
Yangjun Zhang ◽  
Hong He ◽  
Zhiling Qiu
Keyword(s):  
Fuel Cell ◽  
Centrifugal Compressor ◽  
Electric Motor ◽  
High Speed ◽  
High Efficiency ◽  
Pressure Ratio ◽  
System A ◽  
Automotive Fuel ◽  
Low Specific Speed ◽  
Specific Speed

Centrifugal compressors driven by electric motor are the promising type for fuel cell pressurization system. A low specific speed centrifugal compressor powered by an ordinary high-speed (about 25,000rpm) electric motor has been designed at Tsinghua University for automotive fuel cell engines. The experimental results indicate that the designed low specific speed centrifugal compressor has comparatively high efficiency and wide operating range. In the condition of designed speed (24,000rpm), the highest efficiency and pressure ratio of the centrifugal compressor is up to 70% and 1.6, respectively. The designed low specific speed centrifugal compressor can meet the requirement of air systems of automotive fuel cell engines preliminarily. Moreover, the low specific speed centrifugal compressor avoids difficulties of usage of ultra-high-speed electric motors (about 60,000rpm) in high specific speed compressor. Based on the preliminary results of this centrifugal compressor, a new low specific speed centrifugal compressor with higher performances is being developed.

Sign in / Sign up

Export Citation Format

Share Document