An Experimental Investigation on the Wake Flow Characteristics of Tandem Flapping Wings

2011 ◽  
Author(s):  
Anand Kumar ◽  
Hui Hu
Keyword(s):  
Experimental Investigation ◽  
Flow Characteristics ◽  
Wake Flow ◽  
Flapping Wings ◽  
Tandem Flapping Wings

On the Propulsive Performance of Tandem Flapping Wings with a Modified Immersed Boundary Method

2016 ◽  
Vol 13 (05) ◽  
pp. 1650025 ◽  
Author(s):  
Dingyi Pan ◽  
Jian Deng ◽  
Xueming Shao ◽  
Zubin Liu
Keyword(s):  
Immersed Boundary Method ◽  
Thrust Force ◽  
Wake Flow ◽  
Flapping Wings ◽  
Immersed Boundary ◽  
Phase Lag ◽  
Boundary Method ◽  
Total Thrust ◽  
Tandem Flapping Wings ◽  
The One

The modified immersed boundary method is introduced and applied to study the propulsive mechanism of a tandem flapping wings system. The effects of tandem wings distance and phase lag between the two flapping wings are investigated. Thrust force of the upstream wing is nearly constant and close to the magnitude of single flapping wing system. Thrust force of second wing is influenced by the distance and phase lag. With specific parameters, the second wing can obtain a maximum thrust which is larger than the one of first wing. The flow structures of the wake flow are classified into three different formations, and they are correlated to the trends of thrust force. The effects of distance and phase lag are coupled other than isolated. It is possible to lower down the power consumption of this tandem flapping wings system and enhance the total thrust force of the system at the same time.

Experimental Investigation of Effect of Tip Coolant Ejection on Internal Flow Characteristics Within a Realistic Blade Coolant Channel

2013 ◽  
Author(s):  
Jian Pu ◽  
Zhaoqing Ke ◽  
Jianhua Wang ◽  
Lei Wang ◽  
Hongde You
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Turbine Blade ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Flow Ratio ◽  
Lp Turbine ◽  
Mass Flow Ratio

This paper presents an experimental investigation on the characteristics of the fluid flow within an entire coolant channel of a low pressure (LP) turbine blade. The serpentine channel, which keeps realistic blade geometry, consists of three passes connected by a 180° sharp bend and a semi-round bend, 2 tip exits and 25 trailing edge exits. The mean velocity fields within several typical cross sections were captured using a particle image velocimetry (PIV) system. Pressure and flow rate at each exit were determined through the measurements of local static pressure and volume flow rate. To optimize the design of LP turbine blade coolant channels, the effect of tip ejection ratio (ER) from 180° sharp bend on the flow characteristics in the coolant channel were experimentally investigated at a series of inlet Reynolds numbers from 25,000 to 50,000. A complex flow pattern, which is different from the previous investigations conducted by a simplified square or rectangular two-pass U-channel, is exhibited from the PIV results. This experimental investigation indicated that: a) in the main flow direction, the regions of separation bubble and flow impingement increase in size with a decrease of the ER; b) the shape, intensity and position of the secondary vortices are changed by the ER; c) the mass flow ratio of each exit to inlet is not sensitive to the inlet Reynolds number; d) the increase of the ER reduces the mass flow ratio through each trailing edge exit to the extent of about 23–28% of the ER = 0 reference under the condition that the tip exit located at 180° bend is full open; e) the pressure drop through the entire coolant channel decreases with an increase in the ER and inlet Reynolds number, and a reduction about 35–40% of the non-dimensional pressure drop is observed at different inlet Reynolds numbers, under the condition that the tip exit located at 180° bend is full open.

scholarly journals Calibration and validation of the Dynamic Wake Meandering model Part I: Bayesian estimation of model parameters using SpinnerLidar-derived wake characteristics

2021 ◽  
Author(s):  
Davide Conti ◽  
Nikolay Dimitrov ◽  
Alfredo Peña ◽  
Thomas Herges
Keyword(s):  
Wind Farm ◽  
Atmospheric Stability ◽  
Flow Characteristics ◽  
Uncertainty Assessment ◽  
Wake Flow ◽  
Model Parameters ◽  
Wake Field ◽  
Wind Speeds ◽  
Standard Lead ◽  
Estimation Of Model Parameters

Abstract. In this first part of a two-part work, we study the calibration of the Dynamic Wake Meandering (DWM) model using high spatial and temporal resolution SpinnerLidar measurements of the wake field collected at the Scaled Wind Farm Technology (SWiFT) facility located in Lubbock, Texas, U.S.A. We derive two-dimensional wake flow characteristics including wake deficit, wake turbulence and wake meandering from the lidar observations under different atmospheric stability conditions, inflow wind speeds and downstream distances up to five rotor diameters. We then apply Bayesian inference to obtain a probabilistic calibration of the DWM model, where the resulting joint distribution of parameters allows both for model implementation and uncertainty assessment. We validate the resulting fully-resolved wake field predictions against the lidar measurements and discuss the most critical sources of uncertainty. The results indicate that the DWM model can accurately predict the mean wind velocity and turbulence fields in the far wake region beyond four rotor diameters, as long as properly-calibrated parameters are used and wake meandering time series are accurately replicated. We demonstrate that the current DWM-model parameters in the IEC standard lead to conservative wake deficit predictions. Finally, we provide practical recommendations for reliable calibration procedures.

Characteristics of Miniature Short-Tube Orifice Flows

1989 ◽  
Vol 203 (5) ◽  
pp. 351-358 ◽  
Author(s):  
T A Fox ◽  
J Stark
Keyword(s):  
Experimental Investigation ◽  
Critical Pressure ◽  
Fuel Injection ◽  
Flow Characteristics ◽  
Head Loss ◽  
Differential Pressure ◽  
Pressure Differential ◽  
Contraction Parameter ◽  
Volumetric Discharge ◽  
Short Tube

This paper presents the results of an experimental investigation into the flow characteristics of miniature short-tube orifices of a type commonly used for fuel injection. From measurements of differential pressure and volumetric discharge it is shown that these devices are susceptible to a cavitation-induced instability phenomenon known as hydraulic flip. It was found that this instability is limited to orifices of length less than fourteen diameters and occurs at a critical pressure differential which varies as a function of the orifice l/d ratio and contraction parameter β. In addition, the performance of the device is examined in terms of the head loss characteristics and it is shown that the mechanisms associated with hydraulic flip have a significant effect on the efficiency of discharge.

Experimental investigation on flow characteristics in circular tube inserted with rotor-assembled strand using PIV

2019 ◽  
Vol 27 (1) ◽  
pp. 1-9
Author(s):  
Lichen He ◽  
Weimin Yang ◽  
Changfeng Guan ◽  
Hua Yan ◽  
Lin Zheng ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Circular Tube ◽  
Flow Characteristics
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