On strong blowing into an incompressible airstream

1973 ◽  
Vol 60 (2) ◽  
pp. 241-255 ◽  
Author(s):  
F. T. Smith
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Velocity Profile ◽  
Air Injection ◽  
Relative Mass ◽  
Pressure Measurements ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Strong Injection ◽  
Steady Laminar

An experimental study of distributed air-injection from a porous section of a flat plate into a uniform incompressible airflow is described. The relative mass flow rates of the injection varied between 0·008 and 0·053 (strong injection) and the blowing was fairly uniformly distributed. In the resulting flow field, which was predominantly laminar except near the dividing streamline, where unsteadiness prevailed, velocity profile and pressure measurements were taken and the position of the dividing streamline thereby estimated. Overall the results agree fairly well with the steady laminar theory for strong normal blowing, outlined in §2, although for the strongest blow some signs of separation some way upstream of the blow are apparent.

scholarly journals Thermal Performance of Solar Collectors with EPDM Absorber Plates

1988 ◽  
Vol 41 (4) ◽  
pp. 623
Author(s):  
MJ O'Keefe ◽  
JLA Francey
Keyword(s):  
Experimental Study ◽  
Thermal Resistance ◽  
Flat Plate ◽  
Heat Loss ◽  
Thermal Performance ◽  
Critical Value ◽  
Solar Collectors ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
High Thermal Resistance

An experimental study of flat-plate solar collectors using ethylene, propylenediene monomer (EPDM) absorber plates is descn"bed. In spite of the high thermal resistance of this material the performance is found to compare well with metal absorbers and to be in agreement with the Hottel-Whillier-Bliss equation. There is, however, an observed increase in the heat loss coefficient for mass flow rates below a critical value.

LDV Measurements and Investigation of Flow Field Through Radial Turbine Guide Vanes

1991 ◽  
Vol 113 (4) ◽  
pp. 660-667
Author(s):  
Hasan Eroglu ◽  
Widen Tabakoff
Keyword(s):  
Flow Field ◽  
Flow Direction ◽  
Mean Flow ◽  
Flow Rates ◽  
Radial Turbine ◽  
Contour Plots ◽  
Mass Flow Rates ◽  
Flow Turbulence ◽  
Downstream Flow ◽  
Nozzle Blade

The results of LDV measurements and investigation of the detailed flow field in a radial inflow turbine nozzle are presented. The flow velocities were measured at upstream, inside and downstream of the nozzle blades for two different mass flow rates, using a three-component LDV system. Results are presented as contour plots of mean velocities, flow angles, and turbulence intensities. The flow field inside the nozzle blade passages was found to be influenced by the upstream scroll geometry. The flow turbulence increased in the downstream flow direction. The LDV mean flow results on the blade-to-blade midspan plane which is parallel to the end walls were also compared with an inviscid, “panel method” solution.

Compressible Flow Ejectors: Part II—Flow Field Measurements and Analysis

1974 ◽  
Vol 96 (3) ◽  
pp. 282-288 ◽  
Author(s):  
K. R. Hedges ◽  
P. G. Hill
Keyword(s):  
Experimental Study ◽  
Mach Number ◽  
Mass Flow ◽  
Field Measurements ◽  
Flow Ratio ◽  
Flow Rates ◽  
Jet Mixing ◽  
Mass Flow Rates ◽  
Exit Mach Number ◽  
Mass Flow Ratio

An experimental study has been made of compressible jet mixing in an axisymmetric ejector of converging-diverging geometry. The mass flow ratio was in the range 1.3 to 2.6 and the nozzle exit Mach number was 1.82. Ejector performance characteristics were obtained as well as measurements of pressure and velocity distribution over a range of mass flow rates. The experimental results were used to test the reliability of the analytical model of the flow described in Part I of the paper.

Effect of nozzle angle, turbine inlets and mass flow rate on the performance of a bladeless turbine

2019 ◽  
Vol 234 (8) ◽  
pp. 1101-1107
Author(s):  
Muhammad Ali Kamran ◽  
Shahryar Manzoor
Keyword(s):  
Experimental Study ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Working Fluid ◽  
Operating Parameters ◽  
Lower Mass ◽  
Flow Rates ◽  
Significant Parameter ◽  
Mass Flow Rates

A comprehensive experimental study on the effects of different operating parameters on the efficiency of tesla turbine is reported. A bladeless turbine with nine discs and up to four turbine inlets was used, with water as the working fluid. The parameters investigated are the nozzle angle, number of turbine inlets and mass flow rates. Contrary to earlier studies, an effort was made to determine the performance under varying loading conditions, and hence identify the complete performance characteristics. The study revealed that efficiency of the turbine increases at lower nozzle angles and higher number of turbine inlets. It was observed that the nozzle angle becomes a significant parameter when the number of turbine inlets is increased. Efficiencies up to 78% were achieved when the working fluid entered the turbine through two nozzles at an angle of 7°. It was also noted that the turbine is most efficient at the designed mass flow rate, and the efficiency reduces appreciably if lower mass flow rates are fed to the turbine. The results obtained are an important contribution to the available knowledge and can be used as design references for further studies.

An Experimental Study of a “Once-Through” Thermosiphon System

1988 ◽  
Vol 110 (2) ◽  
pp. 90-97 ◽  
Author(s):  
R. Celentano ◽  
R. Kirchner
Keyword(s):  
Experimental Study ◽  
Mass Flow ◽  
Natural Circulation ◽  
Time Dependent ◽  
Circulation System ◽  
Outlet Temperature ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
New Type ◽  
Mass Flows

An experimental study was conducted on the operation of a “once-through” thermosiphon system. This new type of natural circulation system, unlike the standard thermosiphon system, heats the collector fluid in one pass without any recirculation. An electrically heated manifold was used to simulate the useful solar gain. Power was varied with time in 22 half-hour increments to simulate the actual daily useful solar gain. The time-dependent responses of the system in terms of temperatures and mass flow rates were recorded and plotted. The response time for mass flow and temperature to approach steady state varied directly with the size of the power step. Two experiments were conducted; one which tracked mass flows and outlet temperatures for variable useful solar gains, and a second which tracked mass flows at constant outlet temperature for variable useful solar gains.

Flow of Yield Power Law Fluids in Horizontal Pipes-Flow Field Characterization Using Particle Image Velocimetry Technique

2021 ◽  
Author(s):  
Yanxin (Sussi) Sun ◽  
Abdulla Abou-Kassem ◽  
Majid Bizhani ◽  
Ergun Kuru
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Velocity Profile ◽  
Yield Stress ◽  
Power Law ◽  
Pipe Flow ◽  
Hydrodynamic Behaviour ◽  
Yield Stress Fluids ◽  
Power Law Fluids ◽  
Flow Field Characteristics

Abstract Yield Power Law (YPL) rheological model is commonly used to describe the pipe and annular flow of drilling fluids. However, the hydrodynamic behaviour of fluids with yield stress are difficult to predict because they exhibit an inherent plug (solid like) region where the velocity gradient is zero. Moreover, it is not easy to identify the transition between this solid like and liquid regions. Theoretical studies have been conducted in the past to describe YPL fluid flow in pipes and annuli. As a result, several models have been proposed for determining flow field characteristics (e.g. velocity profile, plug width, etc.) and frictional pressure losses. However, most of these models have been validated by limited experimental and/or field data. Similar future modeling studies may benefit from more data collected under controlled experimental conditions. Therefore, we have conducted an experimental study to investigate the hydrodynamic behaviour of yield stress fluids under laminar pipe flow conditions and the results are presented in this paper. Water-based Yield Power Law fluids were prepared by using Carbopol® 940, a synthetic high-molecular-weight polyacrylic acid-based cross-linked polymer. Fluids with yield stresses varying from 0.75 Pa (1.56 lb/100 ft2) to 4.37 Pa (9.13 lb/100 ft2) were obtained by using Carbopol concentrations changing from 0.060% w/w to 0.073% w/w. A 9m long horizontal pipeline with, 95 mm diameter (ID) was used for the experiments. Reynolds number range varying from 97 to 1268 confirmed that all flow field characteristics measurements of YPL fluids were conducted under laminar flow regimes. Experimental study provided detailed information about pipe flow characteristics of yield stress fluids, including full annular velocity profile, near wall velocity profile, wall slip velocity and the plug region thickness. The study was concluded by comparing experimental results (i.e. full velocity profile, frictional pressure loss, and plug width) to predictions of models presented in the literature. Practical implications of the results have also been discussed by considering the hydraulic design of some practical field operations such as hole cleaning.

Experimental Investigation of Turbine Leakage Flows on the Three-Dimensional Flow Field and Endwall Heat Transfer

2006 ◽  
Vol 129 (3) ◽  
pp. 608-618 ◽  
Author(s):  
Hans-Jürgen Rehder ◽  
Axel Dannhauer
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Secondary Flow ◽  
Mass Flow ◽  
Test Section ◽  
Flow Behavior ◽  
Leakage Flow ◽  
Flow Rates ◽  
Low Pressure Turbine ◽  
Mass Flow Rates

Within a European research project, the tip endwall region of low pressure turbine guide vanes with leakage ejection was investigated at DLR in Göttingen. For this purpose a new cascade wind tunnel with three large profiles in the test section and a contoured endwall was designed and built, representing 50% height of a real low pressure turbine stator and simulating the casing flow field of shrouded vanes. The effect of tip leakage flow was simulated by blowing air through a small leakage gap in the endwall just upstream of the vane leading edges. Engine relevant turbulence intensities were adjusted by an active turbulence generator mounted in the test section inlet plane. The experiments were performed with tangential and perpendicular leakage ejection and varying leakage mass flow rates up to 2%. Aerodynamic and thermodynamic measurement techniques were employed. Pressure distribution measurements provided information about the endwall and vane surface pressure field and its variation with leakage flow. Additionally streamline patterns (local shear stress directions) on the walls were detected by oil flow visualization. Downstream traverses with five-hole pyramid type probes allow a survey of the secondary flow behavior in the cascade exit plane. The flow field in the near endwall area downstream of the leakage gap and around the vane leading edges was investigated using a 2D particle image velocimetry system. In order to determine endwall heat transfer distributions, the wall temperatures were measured by an infrared camera system, while heat fluxes at the surfaces were generated with electric operating heating foils. It turned out from the experiments that distinct changes in the secondary flow behavior and endwall heat transfer occur mainly when the leakage mass flow rate is increased from 1% to 2%. Leakage ejection perpendicular to the main flow direction amplifies the secondary flow, in particular the horseshoe vortex, whereas tangential leakage ejection causes a significant reduction of this vortex system. For high leakage mass flow rates the boundary layer flow at the endwall is strongly affected and seems to be highly turbulent, resulting in entirely different heat transfer distributions.

scholarly journals ŠILUMNEŠIO DEBITO ĮTAKOS FAZINIO VIRSMO MEDŽIAGOS VEIKIMUI TYRIMAS / INVESTIGATION OF THE INFLUENCE OF MASS FLOW RATE ON PHASE CHANGE MATERIAL BEHAVIOUR

2019 ◽  
Vol 11 (0) ◽  
pp. 1-5 ◽  
Author(s):  
Saulius Pakalka ◽  
Kęstutis Valančius ◽  
Matas Damonskis
Keyword(s):  
Experimental Study ◽  
Phase Change ◽  
Mass Flow Rate ◽  
Phase Change Material ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Transfer Fluid ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Change Material

The paper presents an experimental study of the influence of heat transfer fluid (HTF) mass flow rate on phase change materials (PCM) behaviour. The experimental study was performed on a specially designed test bench. Research object – PCM based thermal energy storage unit which consists of a stainless steel tank with dual circuit tube-fin copper heat exchanger. The tank (storage volume) was filled with phase change material RT82. The experiment was carried out using three different mass flow rates of HTF: high – 0.25 kg/s, medium – 0.125 kg/s, low – 0.05 kg/s. The analysis showed that in the case of high and medium mass flow rates the melting/solidification process highly depends on the temperature of inlet HTF. Influence of mass flow rate is higher in the case of low mass flow rate.

Experimental Investigation of Turbine Leakage Flows on the 3D Flow Field and End Wall Heat Transfer

2006 ◽  
Author(s):  
Hans-Ju¨rgen Rehder ◽  
Axel Dannhauer
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Secondary Flow ◽  
Mass Flow ◽  
Flow Behavior ◽  
Leakage Flow ◽  
Wall Heat Transfer ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
End Wall

Within a European research project the tip end wall region of LP turbine guide vanes with leakage ejection was investigated at DLR in Go¨ttingen. For this purpose a new cascade wind tunnel with three large profiles in the test section and a contoured end wall was designed and built up, representing 50% height of a real low pressure turbine (LPT) stator and simulating the casing flow field of shrouded vanes. The effect of tip leakage flow was simulated by blowing air through a small leakage gap in the end wall just upstream of the vane leading edges. Engine relevant turbulence intensities were adjusted by an active turbulence generator mounted in the test section inlet plane. The experiments were performed with tangential and perpendicular leakage ejection and varying leakage mass flow rates up to 2%. Aerodynamic and thermodynamic measurement techniques were employed. Pressure distribution measurements provided information about the end wall and vane surface pressure field and its variation with leakage flow. Additionally streamline pattern (local shear stress directions) on the walls were detected by oil flow visualization. Downstream traverses with 5-hole pyramid type probes allow a survey of the secondary flow behavior in the cascade exit plane. The flow field in the near end wall area downstream of the leakage gap and around the vane leading edges was investigated using a 2D Particle Image Velocimetry (PIV) system. In order to determine end wall heat transfer distributions, the wall temperatures were measured by an infra-red camera system, while heat fluxes at the surfaces were generated with electric operating heating foils. It turned out from the experiments that distinct changes in the secondary flow behavior and end wall heat transfer mainly occur when the leakage mass flow rate is increased from 1% to 2%. Leakage ejection perpendicular to the main flow direction amplifies the secondary flow, in particular the horse-shoe vortex, whereas tangential leakage ejection causes a significant reduction of this vortex system. For high leakage mass flow rates the boundary layer flow at the end wall is strongly affected and seems to be highly turbulent, resulting in entirely different heat transfer distributions.

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