Laboratory for Thermodynamics and Fluid Dynamics Engineering (LWS)

• Gas turbine test stand for model turbines (Brayton cycle, measurement data recording)
• Shallow water channel (2-D model consideration, laws of similitude)
• Refrigerating machine (Rankine cycle (anti-clockwise), humid air)
• Fan test bench (fan characteristic, volume flow measurement)
• Stirling engine (Stirling cycle)
• Injection pump test bench
• Supersonic wind tunnel (supercritical flow, Mach cone)
• Striation optics to visualise density differences (speed, temperature, various gaseous media)
• Soundproof cabin
• Measuring devices

Measuring devices

Various measurement systems and methods are available, some of which are listed here:

• Pressure (-1 to 2,500 bar)
• Temperature with thermocouples, radiation pyrometer, thermal imaging camera
• Speed measurement, air (0.1 to 40 m/s)
• Volume flow, water (7.5 to 1,150 l/min)
• Mass flow, air (3 to 1,000 kg/h)
• Humidity (0 to 100% relative humidity)
• Particle size measurement (1 to 400 µm)
• Surface tension of liquids
• Vibration measurement with acceleration transducers (1 and 3-dimensional, to 500g)
• Sound intensity measurement, acoustic power
• Measurement data recording and processing with LabView from National Instruments
• Dynamic signal analyser for fast processes

Modelling techniques, visualisation

• Small shallow water channel (measuring bench 500 x 700 mm)
• Large shallow water channel (measuring bench 1,600 x 2,000 mm)
• Small wind tunnel (cross-section 330 x 330 mm (450 x 450), 30 m/s)
• Large wind tunnel (measuring cross-section Ø 700 mm, 60 m/s)
• Smoke generator
• Schlieren optics, interferometer (Object size to 25 cm) to visualise density differences
• Thermal imaging camera
• Flow simulation CFD

Simulation

• Visualisation

To consolidate the lectures in thermodynamics, hydrokinetic flow machines and metrology, the following practical laboratory exercises are offered:

Thermodynamics laboratory

• Refrigerating machine
  • Measurement of an anti-clockwise Clausius-Rankine cycle
  • Evaluation and graphical representation of the process
• Humid air
  • State change humid air
  • h-x diagram
  • Psychrometer (measurement of relative humidity)
• Stirling engine
  • Recording of the critical points
  • Evaluation and graphical representation of the process
• Steam power process

Hydrokinetic flow machines laboratory

• Shallow water channel
  • Transferability of fluid technology analogies with the aid of the laws of similitude and characteristic numbers in fluid engineering
  • Flow visualisation using models
• Fan test bench
  • Calculation of the machine data from the measured values
  • Determination of the fan characteristic at different (rotational) speeds
  • Determination of the efficiency and graphic representation
• Gas turbine
  • Measurement of various parameters and operating variables on a gas turbine for aircraft models
  • Evaluation of the measurement data and calculation of the characteristics of the cycle
• Supersonic wind tunnel
  • Demonstration of a supersonic flow
  • Visualisation of a [super]sonic boom (Mach cone) with an interferometer

Metrology laboratory

• Temperature experiment
  • Familiarisation with temperature sensors operating with different measurement principles and designs, as well as operation of measurement data recorders and software
  • Manual evaluation of the measurement data recorded to enhance understanding
• Pressure measurement
  • Connection, setting up and operation of a measurement chain comprising a measurement amplifier and pressure sensor
  • Calibration of a pressure sensor.
  • Operation of and practice with a storage oscilloscope
  • Investigation of the dynamic behaviour of a pressure sensor in the event of a pressure jump
• Flow rate measurement
  • Determination of the measurands at a Venturi nozzle and calculation of volume and mass flow
  • Calibration of a hot-wire mass air-flow sensor on a fan test bench
  • Evaluation.

• Flow resistance and evaluation of measurement data

  • Determination of the flow resistance of compressed air hoses of different diameters.

  • Best-fit approximation of the measurement curve.

• Measurement System Analysis

  • Exemplary investigation of the measurement system analysis using a caliper.

• Electronic scale

  • Arduino programming and calibration of a bending beam.

The equipment and experience of the LWS have led to numerous contacts in various branches of industry. The activities are naturally in the field of metrology, thermodynamics and fluid dynamics engineering, but are not restricted to classical mechanical engineering.

Projects with a medical engineering background have also been undertaken in the past.

Depending on their size, the scientific investigations are conducted by one or more project groups and supervised by the specialist professors and laboratory staff.

Some project examples are listed below:

ApisJet

In this major project at the Institute of Applied Research, a glider of the type Apis 2 will be equipped with a jet engine. Instead of the existing retractable auxiliary engine with propeller, a jet engine will be used and act as the sustainer engine - the ultralight glider is not able to self-launch.
Experiments and measurements for the individual projects are conducted in the LWS.

Voice prostheses

For patients who have had a full or partial laryngectomy, voice prostheses (small valve flaps) are inserted between oesophagus and windpipe to enable the patient to speak after such an operation.
Measurement data is required to qualify these diaphragm valves.
Student projects have involved developing an experimental set-up to measure the pressure-volume flow characteristic, the opening pressure and the long-term stability of different voice prostheses and performing related measurements.

Vibration studies on hand-held electrical equipment

Against the background of the European Directive 2002/44/EC (Physical Agents Directive Vibration), the relevant vibration measuring norms in the DIN EN 60745-1 and EN 60745-2-x standards for hand-held electric tools are currently being revised.
The task of the R&D project was to carry out vibration measurements on hand-held electric tools to determine influencing factors such as the position and number of measurement transducers, practice measurements, wear of electric tools, etc.
The objective of these investigations is not the direct comparison of machines from different manufacturers, but to improve the measurement method and obtain more detailed knowledge of the metrological interconnections.

Fuel cell battery

Part of the project was to set up a prototype and develop it further; this involved selecting components which are commercially available to set up a fuel cell system and using it for demonstration purposes in the laboratory.