Experimental investigation of the flow characteristics of small orifices and valves in water hydraulics

2002 ◽  
Vol 216 (4) ◽  
pp. 235-245 ◽  
Author(s):  
Zhu Bikai ◽  
Huang Yan ◽  
Zhang Tiehua ◽  
Li Zhuangyun
Keyword(s):  
Experimental Investigation ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Test Results ◽  
Small Opening ◽  
Aspect Ratios ◽  
Water Hydraulics ◽  
Different Shapes ◽  
Large Opening ◽  
Spool Valve

This paper describes an experimental investigation of the flow characteristics of water passing through small sharp-edged cylindrical orifices and valves of different shapes in water hydraulics. The test results using orifices with aspect ratios, l/d, of 1–15 and diameters of 0.8-3 mm show that the flow coefficients in the case of non-cavitating flow are larger than those of flow with cavitation and decrease with increase in the aspect ratio. However, the flow coefficients of flow with cavitation tend to be of constant value close to the contraction coefficient, Cc at small aspect ratios. Orifices with large aspect ratios have the effect of suppressing cavitation. Experimental results concerning the spool valve illustrate that the sharp-edged valve is less cavitation stricken at large opening than at small opening. Throttles with a triangular notch have better anticavitation ability than those with a square notch. The flow of the throttle with a square notch is significantly affected by the flow direction and the shape of the flow passage.

scholarly journals Physical Modeling of Flow Field inside Urban Street Canyons

2008 ◽  
Vol 47 (7) ◽  
pp. 2058-2067 ◽  
Author(s):  
Xian-Xiang Li ◽  
Dennis Y. C. Leung ◽  
Chun-Ho Liu ◽  
K. M. Lam
Keyword(s):  
Numerical Modeling ◽  
Flow Pattern ◽  
Numerical Models ◽  
Flow Direction ◽  
Water Channel ◽  
Flow Characteristics ◽  
Street Canyons ◽  
Urban Street ◽  
Urban Street Canyons ◽  
Aspect Ratios

Abstract The flow characteristics inside urban street canyons were studied in a laboratory water channel. The approaching flow direction was horizontal and perpendicular to the street axis. The street width was adjusted to form street canyons of aspect ratios 0.5, 1.0, and 2.0. The velocity field and turbulent intensity were measured with a laser Doppler anemometer at various locations within the street canyons, which were used to elucidate the flow pattern inside the street canyons. It was found that the previous numerical modeling results are in good agreement with the current experimental results at most locations. For the street canyon of aspect ratio 0.5, which belongs to the wake interference flow regime, the mean and fluctuating velocity components were more difficult to measure as compared with the other two cases because of its more complicated flow pattern. Some guidelines for numerical modeling were developed based on the measurement results. The data presented in this paper can also be used as a comprehensive database for the validation of numerical models.

An Experimental Investigation on Internal Flow Characteristics in a Realistic and Entire Coolant Channel With Ribs and Film Holes

2018 ◽  
Author(s):  
Peng Wang ◽  
Jian Pu ◽  
Ren-bin Yu ◽  
Jian-hua Wang ◽  
Bo Wan ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Separation Bubble ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Main Flow ◽  
Particle Image Velocimetry Technique ◽  
Cross Sectional ◽  
Flow Acceleration ◽  
Sharp Bend ◽  
Secondary Vortices

This paper presents an experimental investigation on the flow characteristics within an entire coolant channel of a 2nd stage high pressure (HP) static turbine blade using TRPIV (Time-Resolution Particle Image Velocimetry) technique. The serpentine channel with three passages connected by a sharp bend, a round bend, 2 tip exits, 8 tailing exits and 40 film-holes staggered arranged on pressure side (PS) of the third pass is chosen as specimen, whose cross sections are manufactured to keep the real blade-shape. Ribs with a fixed spacing-to-height of 7 and an angle of 60° to the flow direction are applied on two opposite walls. The experiment is carried out at a fixed inlet Reynolds number of Rein = 23508. The variation process of secondary vortices and the main flow patterns in typical planes of the realistic coolant channel are successfully captured by TRPIV technique. The effects of rib, bend, cross-sectional shape, layout of passages, ejection ratio on the flow characteristics are analyzed and discussed. The following five new phenomena can be obtained. Namely, 1) near the two bend-regions, the rib can reduce the size of separation bubble and generate a new flow-acceleration downstream of the rib. 2) The rib-vortices combined with the mixing vortex caused by the bend and layout of channels, which leads to a new pair of vortices downstream of the bend, and further downstream, in the pair of vortices, the larger vortex presses the smaller vortex to form a new large vortex. This phenomenon has not been captured up to now in simplified ribbed two-pass channels and smooth realistic channels. 3)The development process of the secondary vortices and asymmetric behavior of main flow structure are similar in the regions of the sharp and round bends. 4)The coolant ejection from the tip exit in the sharp bend can decrease the mixing speed of the secondary vortices downstream of the bend. 5)The tip ejection from the trailing edge exits and film holes can reduce of the size of the secondary vortices downstream of the bend.

scholarly journals Experimental Investigation on Composite Deck Slab Made of Cold-Formed Profiled Steel Sheeting

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 229
Author(s):  
Siva Avudaiappan ◽  
Erick I. Saavedra Flores ◽  
Gerardo Araya-Letelier ◽  
Walter Jonathan Thomas ◽  
Sudharshan N. Raman ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Test Results ◽  
Shear Connectors ◽  
Modes Of Failure ◽  
Deck Slabs ◽  
Load Carrying ◽  
Composite Slabs ◽  
Ultimate Load Carrying Capacity ◽  
Ductility Ratio ◽  
Deck Slab

An experimental investigation is performed on various cold-formed profiled sheets to study the connection behavior of composite deck slab actions using bolted shear connectors. Various profiles like dovetailed (or) re-entrant profiles, rectangular profiles and trapezoidal profiles are used in the present investigation. This experimental investigation deals with the evaluation of various parameters such as the ultimate load carrying capacity versus deflection, load versus slip, ductility ratio, strain energy and modes of failure in composite slab specimens with varying profiles. From the test results the performance of dovetailed profiled composite slabs’ resistance is significantly higher than the other two profiled composite deck slabs.

Research of the Connecting Form about the Spherical Shell and the Nozzle

2011 ◽  
Vol 413 ◽  
pp. 520-523
Author(s):  
Cai Xia Luo
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Spherical Shell ◽  
Maximum Stress ◽  
Peak Stress ◽  
Element Model ◽  
Small Opening ◽  
Large Opening ◽  
Reducing Stress

The Stress Distribution in the Connection of the Spherical Shell and the Opening Nozzle Is Very Complex. Sharp-Angled Transition and Round Transition Are Used Respectively in the Connection in the Light of the Spherical Shell with the Small Opening and the Large One. the Influence of the Two Connecting Forms on Stress Distribution Is Analyzed by Establishing Finite Element Model and Solving it. the Result Shows there Is Obvious Stress Concentration in the Connection. Round Transition Can Reduce the Maximum Stress in Comparison with Sharp-Angled Transition in both Cases of the Small Opening and the Large Opening, Mainly Reducing the Bending Stress and the Peak Stress, but Not the Membrane Stress. the Effect of Round Transition on Reducing Stress Was Not Significant. so Sharp-Angled Transition Should Be Adopted in the Connection when a Finite Element Model Is Built for Simplification in the Future.

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.

Experimental Investigation on Relative Crack Length For Fracture Toughness of Concrete

2010 ◽  
Vol 146-147 ◽  
pp. 1524-1528 ◽  
Author(s):  
Xue Zhi Wang ◽  
Zong Chao Xu ◽  
Zhong Bi ◽  
Hao Wang
Keyword(s):  
Fracture Toughness ◽  
Experimental Investigation ◽  
Crack Length ◽  
Fracture Toughness Test ◽  
Test Results ◽  
Toughness Test ◽  
Wedge Splitting Test ◽  
Splitting Test ◽  
Wedge Splitting

The wedge splitting test specimens with three series of different relative crack length were used to study the influences of relative crack length on the fracture toughness of common concrete. The suitable formulation for fracture toughness of concrete with different relative crack length was gotten on comparing between fracture toughness test results and computation results of the model developed from Hu formula.

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