Experimental Investigation on Power Losses due to Oil Jet Lubrication in High Speed Gearing Systems

2017 ◽  
Author(s):  
D. Massini ◽  
T. Fondelli ◽  
B. Facchini ◽  
L. Tarchi ◽  
F. Leonardi
Keyword(s):  
Experimental Investigation ◽  
Mass Flow Rate ◽  
Working Conditions ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Spur Gear ◽  
Lubricating Oil ◽  
Halogen Lamp ◽  
Oil Jet

In order to reduce environmental and climate impact from air traffic, the main effort of aero-engine industry and research community is looking at a continuous increase in gearbox efficiency. With this kind of components every source of loss can be responsible for high heat loads; for this reason oil jet systems are used to provide proper cooling and lubrication of gears tooth surfaces. In the design phase it is important to predict the losses increase due to the lubricating oil jet impact on the spur gear, varying the different geometrical and working parameters such as the jet inclination, distance and the oil mass flow rate and temperature. An experimental investigation was carried out on a novel rotating test rig able to reproduce real engine working conditions in terms of speed, pressure and lubrication system, for a single spur gear. The rig consists of an electric spindle driving a shaft with a spur gear clamped on top. The gear is enclosed in a box where different air pressure conditions can be set and monitored. Pressure transducers and T-type thermocouples placed within the test box were used to measure the gear working conditions. The test box is also equipped with several optical accesses allowing flow field measurements or oil jet visualizations. The driving shaft is composed by two parts connected by a bearingless torquemeter equipped with a speedometer in order to perform torque losses and rotating velocity measurements. Tests were performed without the gear first, in order to separate the final value from the friction losses due to the driving shaft. Windage losses were characterized experimentally for every working condition and the results collected in a simple correlation that was used to separate the losses due to air windage from the ones due to the oil injection. An oil control unit allowed to impose the proper oil pressure and temperature conditions and to measure the mass flow rate. The oil jet was delivered by a spraybar placed within the gearbox, the jet to gear distance and relative angle were varied during the experiments. High speed visualizations were also performed for every test condition in order to deepen the physical understanding of the phenomena and to obtain more information on the lubrication capability of every jet condition. A high speed camera was placed in front of the gear exploiting an optical access while a halogen lamp was used to provide the proper lightening necessary due to the very low exposure time of the acquisitions. The wide experimental database provided, allowed the development of a simple numerical model able to well predict every losses contribution at the various working conditions.

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.

Experimental Investigation on Swirl and Heat Transfer Within a Rotor-Stator Cavity

2016 ◽  
Author(s):  
Daniele Massini ◽  
Bruno Facchini ◽  
Mirko Micio ◽  
Riccardo Da Soghe
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Mass Flow Rate ◽  
Working Conditions ◽  
Mass Flow ◽  
Flow Rate ◽  
System Effect ◽  
Flow Measurements ◽  
Wide Range ◽  
Admission System

A rotating test rig, reproducing a rotor-stator cavity with an axial admission system, has been exploited for an experimental investigation on the internal flow field and its effect on heat transfer on the stator side. Working conditions were varied in a wide range of rotating velocities and superposed mass flow rates. 2D PIV flow measurements were performed in order to obtain a radial distribution of the tangential velocity, results were used to validate numerical simulations aimed at understanding the admission system effect on the swirl distribution. Heat transfer coefficient distribution along the stator disk has been evaluated performing a steady state technique exploiting Thermo-chromic Liquid Crystals (TLC). Tests have been performed varying the superposed mass flow rate up to reaching the condition of cavity completely sealed, further increase of the mass flow rate showed to reduce the effect of the rotation. Working conditions were set in order to investigate cases missing in open literature, however few tests performed in similarity with other researches provided comparable results.

Experimental Investigation of a Pilot Compression Chiller With Alternatives Refrigerants R401a and R134a

2005 ◽  
Author(s):  
M. Fatouh
Keyword(s):  
Experimental Investigation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Water Mass ◽  
Cooling Water ◽  
Cooling Capacity ◽  
Inlet Temperature ◽  
Chilled Water ◽  
Water Mass Flow Rate

This paper reports the results of an experimental investigation on a pilot compression chiller (4 kW cooling capacity) working with R401a and R134a as R12 alternatives. Experiments are conducted on a single-stage vapor compression refrigeration system using water as a secondary working fluid through both evaporator and condenser. Influences of cooling water mass flow rate (170–1900 kg/h), cooling water inlet temperature (27–43°C) and chilled water mass flow rate (240–1150 kg/h) on performance characteristics of chillers are evaluated for R401a, R134a and R12. Increasing cooling water mass flow rate or decreasing its inlet temperature causes the operating pressures and electric input power to reduce while the cooling capacity and coefficient of performance (COP) to increase. Pressure ratio is inversely proportional while actual loads and COP are directly proportional to chilled water mass flow rate. The effect of cooling water inlet temperature, on the system performance, is more significant than the effects of cooling and chilled water mass flow rates. Comparison between R12, R134a and R401a under identical operating conditions revealed that R401a can be used as a drop-in refrigerant to replace R12 in water-cooled chillers.

Condensation-Induced Water Hammer in Horizontal Refrigerant Pipe With Warm Gas Entry

2003 ◽  
Author(s):  
C. Samuel Martin
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Fast Response ◽  
Ammonia Gas ◽  
Pressure Transducers ◽  
High Speed Data Acquisition ◽  
High Speed Data ◽  
Liquid Depth

Careful experiments have been conducted for the purpose of investigating the phenomenon of condensation-induced waterhammer in an ammonia refrigeration system. To initiate a waterhammer event warm ammonia gas was introduced over static subcooled ammonia liquid placed in a horizontal 146.3 mm diameter carbon steel pipe 6.0 m in length. By means of fast response piezoelectric pressure transducers and a high speed data acquisition system rapid dynamic pressures were recorded whenever a shock event occurred. The occurrence of condensation-induced waterhammer depended upon three major variables; namely, (1) initial liquid depth, (2) liquid temperature, and (3) mass flow rate of warm gas. For given liquid depth and temperature, once the warm gas threshold conditions were exceeded shocks occurred with greater magnitude as the mass flow rate of gas input was increased. With adequate subcooling condensation-induced waterhammer occurred for initial liquid depths ranging from 25% to 95% of internal pipe diameter. The threshold mass flow rate of warm gas necessary to initiate waterhammer was greater as the initial liquid was lowered.

Unstart phenomena induced by mass addition and heat release in a model scramjet

2016 ◽  
Vol 797 ◽  
pp. 604-629 ◽  
Author(s):  
S. Im ◽  
D. Baccarella ◽  
B. McGann ◽  
Q. Liu ◽  
L. Wermer ◽  
...  
Keyword(s):  
Heat Release ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Free Stream ◽  
Mass Loading ◽  
High Enthalpy ◽  
Hypersonic Wind Tunnel ◽  
Flow Features

The unstart phenomena in a model scramjet with a free stream Mach number of 4.5 were investigated at an arc-heated hypersonic wind tunnel. High-speed schlieren imaging and high resonance frequency pressure measurements were used to capture the flow features during the unstart process. Three unstart conditions were tested: (i) a low-enthalpy free stream with mass loading, (ii) a high-enthalpy free stream with mass loading and (iii) a high-enthalpy free stream with mass loading and heat release. It was revealed that the unstart threshold and the time from the onset to the completion of unstart depended strongly on the mass loading rate and the heat exchange. The negative heat addition (cooling) significantly increased the threshold of mass flow rate triggering unstart. The decrement of the mass flow rate threshold for unstart was observed in the presence of heat release by combustion. The observed transient and quasi-steady behaviours of the unstart shockwave system and the jet motion were similar in all of the test conditions. On the other hand, at the lip of inlet model, the unstart shockwave under the cold free stream condition exhibited a relatively steady behaviour while severe oscillatory flow motions of the jet and the unstart shockwave were observed in the combustion-driven unstart process. The different unstarted flow behaviours between the three flow conditions were explained using a simplified one-dimensional flow choking analysis and use of the Korkegi criterion.

scholarly journals Quasi 3D Nacelle Design to Simulate Crosswind Flows: Merits and Challenges

2019 ◽  
Vol 4 (3) ◽  
pp. 25 ◽  
Author(s):  
Alex Yeung ◽  
Nagabhushana Rao Vadlamani ◽  
Tom Hynes ◽  
Sumit Sarvankar
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Computational Modelling ◽  
Flow Characteristics ◽  
Attached Flow ◽  
Set Up ◽  
Engine Nacelle ◽  
Shape Changes

This paper studies the computational modelling of the flow separation over the engine nacelle lips under the off-design condition of significant crosswind. A numerical framework is set up to reproduce the general flow characteristics under crosswinds with increasing engine mass flow rate, which include: low-speed separation, attached flow and high speed shock-induced separation. A quasi-3D (Q3D) duct extraction method from the full 3D (F3D) simulations has been developed. Results obtained from the Q3D simulations are shown to largely reproduce the trends observed (isentropic Mach number variations and high-speed separation behaviour) in the 3D intake, substantially reducing the simulation time by a factor of 50. The agreement between the F3D and Q3D simulations is encouraging when the flow either fully attached or with modest levels of separation but degrades when the flow fully detaches. Results are shown to deviate beyond this limit since the captured streamtube shape (and hence the corresponding Q3D duct shape) changes with the mass flow rate. Interestingly, the drooped intake investigated in the current study is prone to earlier separation under crosswinds when compared to an axisymmetric intake. Implications of these results on the industrial nacelle lip design are also discussed.

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