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Details of AF10 AIRFLOW BENCH

AF10 AIRFLOW BENCH

Features

• A basic air flow facility to service TQ experiments or student projects
• A wide range of experiments available for a complete course in air flow
• Textbook "A First Course in Airflow" by Professor E. Markland provided
• Compact and mobile
• No installation - only single phase electrical supply required (except for AF17, requiring a simple exhaust for waste smoke)
• Suitable for lecture theatre demonstrations, laboratory and project work
• Two year warranty
• Complies with the latest EEC Safety Directives

Introduction

This equipment was devised by Professor E. Markland, former Head of Department of Mechanical Engineering, University of Cardiff, for an introductory course in Air Flow.

Description

A fan delivers atmospheric air via an iris valve to a plenum chamber. The iris valve is used for flow control. Various test facilities may be attached to a 350mm x 300mm opening in the plenum chamber. An aerodynamically shaped contraction is supplied with the bench to provide an entry to a number of experiments, having 100mm x 50mm working section. Extensive use is made of toggle fasteners so that no tools are required for fitting the various experiments to the bench. Discharge from the experiments is normally downwards, the exhaust air passing through a pipe let into the bench top and terminating at the rear. This arrangement allows flexible ducting to be fitted (when experiments using smoke are in progress) to lead waste smoke safely away.

Bernoulli's Equation Apparatus AF11

A 100mm x 50mm transparent duct, attached to the contraction, has removable liners, which produce a simple convergent-divergent passage. The pitot-static tube may be traversed along the axis of the duct to show constant total pressure and the rise and fall of static pressure. The significant pressure changes provide a convincing demonstration of Bernoulli's equation and the geometry allows simple calculations to be made and checked against a measurement.

Drag Force Apparatus AF12

The drag force on a cylinder, flat plate and aerofoil, each of the same projected frontal area, may be measured and compared. The cylinder, 12.5mm diameter, has a radial pressure tapping and may be rotated within the 100mm x 50mm transparent working section. Experiments which may be carried out include the following:

1. Determination of drag force by measurement of the pressure distribution around the cylinder.

2. Determination of drag force by wake traverse, using a pitot tube to infer the velocity distribution and momentum flux in the wake.

3. Comparison of the drag force obtained in (1) and (2) with that obtained using the balance provided.

4. Comparison of the results for the cylinder with those for the flat plate and aerofoil, using the drag balance.

Round Turbulent Jet Appartus AF13

A cylindrical tube having an aerodynamically rounded entrance, is fitted to the plenum chamber. The total pressure in the emerging jet maybe measured by means of a pitot tube mounted in a traverse gear, which is arranged so that a diametrical traverse may be made at various sections along the jet axis. Several diameters may be traversed to check the symmetry of the jet. Experiments which may be carried out include the following

1. To observe the decay of centreline velocity.

2. To obtain velocity profile at various distances along the jet and observe the development and spread of the jet.

3. By analysis of the velocity profiles, to show how the mass flux in the jet increases, the kinetic energy flux decreases and the momentum flux remains constant along the length.

Boundary layer Apparatus AF14

A flat plate is placed in the l00mm x 50mm transparent working section so that a boundary layer forms along it. A sensitive, wedge shaped pitot tube mounted in a micrometer traverse allows velocity measurements to be made in the boundary layer. Both laminar and turbulent layers may be formed. Experiments which may be carried out include the measurement of the velocity profile:

1. In laminar and turbulent boundary layers.

2. In the boundary layer on rough and smooth plates.

3. In the boundary layer at various distances from the leading edge of the plate.

4. In the boundary layer on plates subiect to an increasing or decreasing pressure gradient in the direction of flow (using the removable duct liners supplied).

Flow Around a Bend AF15

A transparent bend of l00mm x 50mm cross-section is attached to the contraction; pressure tappings in the wall are grouped and identified as follows:

1. Inner wall, 10 tappings.

2. Outer wall, 10 tappings.

3. 45 radial section, 9 tappings.

4. Reference at inlet, 1 tapping.

These may be rapidly connected to the multitube manometer in groups, using the quick release couplings, and readings taken. Experiments which may be carried out include:

1. Measurement of the pressure distribution along the curved inner and outer walls.

2. Measurement of the radial pressure distribution and comparison with that predicted assuming free vortex velocity distribution.

Jet Attachment Apparatus AF16

The technology of fluidics has evolved from a variety of devices which exploit phenomena of fluid mechanics such as transition from laminar to turbulent flow and jet attachment to a solid wall. In this experiment a jet emerging from a slit impinges on to a wall to which it attaches. The wall may be swung to deflect the jet through a large angle without jet attachment. A second wall may be introduced at the other side of the jet, which may be switched from one side to the other, as is done in the fluidic switch of the type called a flip-flop.

Flow Visualition Apparatus AF17

A special working section may be fitted to the bench to provide flow visualisation facilities. Smoke, produced in a generator supplied with the equipment, is fed to a rake of tubes which produce smoke filaments that flow through the working section, revealing the pattern of flow around obstacles or through restrictions. The standard range of models include a circular cylinder, aerofoil section and a sharp-edged orifice slit. Because of the considerable volume of smoke produced, the exhaust must be vented to the open air, and a flexible duct is provided for this purpose.

Laboratory Textbook

Written specifically around the TQ apparatus, this book discribes the theory and experimental procedures involved, and discusses the results obtained. Also, certain questions are introduced for the student to answer. Title: "A First Course in Air Flow" by professor E. Markland.

Specification

Fan: centrifugal, electric motor driven (push button starter incorporated).

Quantity of air flow: 30m/s in l00 x 50mm working section. 9m3/min

Ancillary

AF10a Multitube Manometer.

Services Required

Earthed single phase a c. 220/240V, 50Hz as standard. Other supplies to suit customers requirements; please specify when ordering. Noise The measured sound pressure level of the experimental apparatus AF10A to AF17 inclusive is less than 70 dB(A). The measured sound pressure level of the AF10 itself:

Dimensions and Weights

AF10

Nett: 1100 x 1000 x 2210mm; 120kg Gross: 2.43m3; 260kg. (approx - packed for export)

Individual experiments

Gross:

(AF11/12/14/15/16): 0.2m3; 10kg

(AF13): 0.08m3; 15kg.

(AF17): 0.10m3; 17kg.

Tender Specification

Apparatus providing basic Air Flow facilities for a variety of experiments, should be fully mobile and suitable for demonstration, laboratory and project work. Should have facility for attaching waste pipe for flow visualisation experiments (having a l00mm x 50mm working section) for a complete course in Air Flow. Should be easy to install with only single phase electrical supply needed, technical manual should be provided. Equipment to be supplied with a two year parts and labour warranty.