scholarly journals Experimental investigation of a high aspect ratio, low speed contra-rotating fan stage with complex inflow distortion

2014 ◽  
Vol 3 (2) ◽  
pp. 68-81 ◽  
Author(s):  
Chetan Mistry ◽  
A.M. Pradeep
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Low Speed

Influence of Circumferential Inflow Distortion on the Performance of a Low Speed, High Aspect Ratio Contra Rotating Axial Fan

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Chetan Mistry ◽  
A. M. Pradeep
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Rotational Speed ◽  
Total Pressure ◽  
Flow Behavior ◽  
Axial Fan ◽  
Low Speed ◽  
Overall Performance ◽  
Design Speed ◽  
Inflow Conditions

The influence of circumferential inflow distorted on the performance and flow behavior of a high aspect ratio, low speed contra rotating fan is reported in this paper. The total pressure at the inlet is artificially distorted by means of 90 deg mesh sector with a porosity of 0.70. The performance of the contra rotating fan was studied under different speed combinations of the two rotors under clean and distorted inflow conditions. Detailed flow analyses were conducted under design and off-design conditions. In order to understand the effect of distortion and its extent, the distortion sector was rotated circumferentially at intervals of 15 deg to cover the entire annulus. Detailed measurements of the total pressure, velocity components, and flow angles were carried out at the inlet of the first rotor, between the two rotors, and at the exit of the second rotor. The study reveals a few interesting aspects on the effect of inflow distortion on the performance of a contra-rotating stage. For the design speed combination and lower rotational speed of rotor-2, a reduction in the overall operating range with a shift of the peak pressure point towards higher mass flow rate, was observed. It is observed that the effect of inflow distortion at the inlet of rotor-1 gets transferred in the direction of rotor-1 rotation and spreads across the entire annulus. The opposite sense of rotation of rotor-2 causes the distortion effect to get transferred in the direction of rotation of rotor-2 with an associated reduction in the total pressure near the hub. It is observed that a higher rotational speed of the second rotor has a beneficial effect on the overall performance due to the strong suction by generated higher rotational speed of rotor-2.

Experimental Investigation of the Evaporation and Stability of a Meniscus in a Flat Microchannel

2011 ◽  
Vol 312-315 ◽  
pp. 1178-1183
Author(s):  
Souad Harmand ◽  
Khellil Sefiane ◽  
Rachid Bennacer ◽  
Nicolas Lancial
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Speed ◽  
Evaporation Rate ◽  
Liquid Meniscus ◽  
Line Region ◽  
Three Phase ◽  
Increasing Temperature ◽  
Insight Into

We present the results of an experimental investigation of the evaporation of a liquid meniscus in a high aspect ratio micro-channel. The study investigates evaporation rates of a stationary liquid meniscus in a high aspect ratio microchannel, the wall of which is electrically heated using transparent resistive coating. Four different liquids are used as working fluids. We report on the dependence of the measured overall evaporation rate on the applied power. The results indicate, and consistently, that the evaporation rate increases with the applied power then peaks before declining. In order to gain insight into these results, we used thermographic infra red imaging to map the temperature field on the external wall of the microchannel. The measurements show that there is a good correlation between the maximum in the evaporative rate and the onset of instabilities of the interface. These instabilities, to our mind, are induced by an increasing temperature gradient along the microchannel wall around the three phase contact line region. These instabilities are revealed by a high speed camera used to record the behaviour of the interface during evaporation.

Numerical and Experimental Investigation of Thermomechanical Deformation in High-Aspect-Ratio Electroplated Through-Silicon Vias

2008 ◽  
Vol 155 (12) ◽  
pp. H981 ◽  
Author(s):  
Pradeep Dixit ◽  
Sun Yaofeng ◽  
Jianmin Miao ◽  
John H. L. Pang ◽  
Ritwik Chatterjee ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Through Silicon Vias ◽  
Thermomechanical Deformation ◽  
Silicon Vias

Effect of Speed Ratio and Axial Spacing Variations on the Performance of a High Aspect Ratio, Low Speed Contra-Rotating Fan

2012 ◽  
Author(s):  
Chetan S. Mistry ◽  
A. M. Pradeep
Keyword(s):  
Aspect Ratio ◽  
Numerical Simulations ◽  
High Aspect Ratio ◽  
Total Pressure ◽  
Experimental Studies ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Stall Margin ◽  
Low Speed

This paper explores the effect of speed ratio and axial spacing between high aspect ratio, low speed contra-rotating pair rotors on their aerodynamic performance. The blades were designed with a low hub-tip ratio of 0.35 and an aspect ratio of 3.0. Numerical and experimental studies are carried out on these contra-rotating rotors operating at a Reynolds number of 1.258 × 105 (based on blade chord). The first and second rotors were designed to develop a pressure rise of 1100 Pa and 900 Pa, respectively, for total mass flow rate of 6 kg/s when both operating at a design speed of 2400 rpm. The performance of the fan was evaluated based on variations of total pressure and flow angles at off-design operating conditions. The measurementsof total pressure rise, flow angles etc. are taken upstream of the first rotor and in between the two rotors and downstream of the second rotor. The performance of the contra rotating stage is mainly influenced by the axial spacing between the rotors and speed ratio of both the rotors. The study reveals that the aerodynamics of the contra-rotating stage and stall margin is significantly affected by both the speed ratio as well as the axial spacing between the rotors. It was found that with increasing the speed ratio, the strong suction generated by the second rotor, improves the stage pressure rise and stall margin. Lower axial spacing changes the flow incidence to the second rotor and thereby improves the overall performance of the stage. This however, is accompanied by an increased noise level. The performance is investigated at different speed ratios of the rotors at varying axial spacing. Detailed numerical simulations have been conducted using ANSYS CFX13© using mixing plane approach between rotors. Numerical simulations are compared with experimental results at off-design conditions. These results are validated using the experimental data. Numerical simulations are expected to provide deeper insight into the flow physics of contra-rotating rotors which may be difficult to capture experimentally.

scholarly journals Experimental Investigation of a Transonic Compressor with High Aspect Ratio Rotor Design

2019 ◽  
Author(s):  
Steffen Hormel ◽  
◽  
Daniel Franke ◽  
Jonas Foret ◽  
Heinz-Peter Schiffer ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Transonic Compressor ◽  
Rotor Design

Investigations on the Effect of Inflow Distortion on the Performance of a High Aspect Ratio, Low Speed Contra Rotating Fan Stage

2013 ◽  
Author(s):  
Chetan S. Mistry ◽  
A. M. Pradeep
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Total Pressure ◽  
Flow Behavior ◽  
Variable Speed ◽  
Low Speed ◽  
Inlet Distortion ◽  
Overall Performance ◽  
Inflow Conditions

In this paper, results from an experimental study on the effect of circumferential inflow distorted on the performance and flow behavior of a high aspect ratio, low speed contra rotating fan, are reported. The total pressure at the inlet is artificially distorted by means of 90° mesh sector having porosity of 0.70. The performance of contra rotating fan was studied under variable speed combinations of rotors under clean and distorted inflow conditions. Detailed flow analyses were conducted under design and off-design conditions. In order to understand the extent of inlet distortion, the distortion sector was rotated circumferentially at intervals of 15° to cover the entire annulus. Detailed measurements of total pressure, velocity components and flow angles were carried out at the inlet of the first rotor, between the two rotors and at the exit of the second rotor. The study reveals a few interesting aspects on the effect of inflow distortion on the performance of a contra-rotating stage. It is observed that a higher rotational speed of the second rotor has a beneficial effect on the overall performance.

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