AC Dynamometers
Provide loading and motoring functions and support dynamic testing. Their speed range, inertia, torque capability, and control response must match the engine and shaft connection.
WEBINAR INSIGHTS | How Can Gas Turbine Testing Reproduce Flight Conditions?
Abstract
Gas turbine testing evaluates how an engine or component performs under defined operating conditions. In aviation, this can include shaft power or thrust, fuel consumption, endurance, and behavior as flight conditions change. This article examines how engine configuration and test objectives guide dynamometer selection, altitude simulation, fuel conditioning and test automation, with examples from HORIBA’s test bench development projects.
Based on the Advanced Gas Turbine Testing webinar presented by Dr. Roberto Tabet, Global Product Manager Engine, HORIBA.
See how HORIBA approaches gas turbine test bench design, altitude simulation and automation.
Test bench design starts with the question the results must answer. Development testing may investigate combustion or component behavior, while validation, endurance, and acceptance testing require different operating sequences and reporting criteria.
For shaft-power engines, torque and rotational speed determine shaft power. Fuel-flow measurements establish consumption at each operating point, while pressure and temperature measurements help explain engine behavior. Other objectives can include performance boundaries, relight after shutdown, alternative-fuel operation, and emissions evaluation.
Engine configuration also shapes the setup:
Configuration | Main testing consideration |
|---|---|
Turboshaft | Shaft power and controlled loading for applications such as helicopter rotor drives |
Turboprop | Shaft-power measurement and loading appropriate to the test objective |
Turbofan or turbojet | Thrust measurement with the required intake and exhaust conditions |
Individual components | Controlled boundary conditions and instrumentation for compressors, combustors, or turbines |
Defining the measurements and operating conditions together helps establish an appropriate facility specification. A shaft-power test bench and a complete-engine thrust test facility have different requirements.
For background on turbine engine operating principles and propulsion configurations, see NASA Glenn’s guide to gas turbine propulsion.
For shaft-power testing, a dynamometer absorbs engine output and establishes the load. Some sequences also require motoring, where the load unit drives the connected shaft.
Selection must consider the torque and speed envelope, time spent at each operating point, and response during transitions. Maximum power is only one part of the specification.
The appropriate configuration depends on the intended sequences and available infrastructure, as well as engine output.
Ground testing assesses engine behavior under ambient conditions unless these are actively controlled. Altitude simulation reproduces selected flight conditions, allowing engineers to investigate performance boundaries and relight behavior during ascent, descent, or changes in airport and seasonal conditions.
HORIBA’s MEDAS configurations offer different conditioning capabilities:
The configuration must match the required pressure, temperature, humidity, airflow, and exhaust conditions.
MEDAS supports altitude simulation, with temperature and humidity capabilities determined by the selected configuration.
Fuel flow, pressure, and temperature affect engine operation and must be controlled and measured for the intended test. Consistent conditions help engineers distinguish fuel effects from changes in the setup.
HORIBA’s fuel systems support different testing requirements:
Hydrogen testing also requires coordinated leak detection, ventilation, extraction, and fuel isolation. Safety thresholds and shutdown sequences must be defined for the specific installation.
HyFQ-2000 measures hydrogen consumption for engine and fuel cell testing.
Automation coordinates the load unit, fuel supply, environmental systems, and instrumentation into defined test sequences. Consistent operating points and data acquisition help engineers compare results and retain the conditions associated with each measurement.
The presentation identifies STARS Automation and STARS Enterprise within HORIBA’s STARS platform, supporting equipment integration, test automation, and data management. The required functions and interfaces should be selected for the project.
Interfaces, recorded signals, and control functions should be defined early. Reports should retain the operating conditions needed to explain differences between runs, alongside the performance results.
Helicopter turbine test bench design presented in the webinar. Workshop maximum-speed testing was conducted without the specimen connected.
The presentation describes a helicopter turbine test bench project using a tandem dynamometer arrangement. The design addresses demanding shaft-power and speed requirements by combining hydraulic power absorption with an electric drive.
At the time of the presentation, the bench was in the workshop and had undergone maximum-speed testing without the specimen connected. This example illustrates test bench development; it should not be interpreted as a completed full-power engine test.
Yes. Compressors, combustion chambers, and turbines can be tested before complete-engine assembly. Equipment must establish the relevant boundary conditions. For combustion chamber testing, this includes an appropriate air supply, fuel supply, and back pressure, with instrumentation matched to the test objective.
Motoring is needed when a sequence requires the load unit to drive the connected shaft. Whether it is required depends on the engine configuration and test objective. AC and suitable tandem dynamometer arrangements can provide this function.
The engine’s airflow demand and the combinations of pressure, temperature, and humidity required by the test program determine the configuration. Exhaust conditions and integration with the rest of the test cell must also be considered.
Reliable gas turbine testing depends on matching the facility to the engine configuration, operating envelope, and engineering questions. Load control, environmental conditioning, fuel delivery, and measurement must work together to establish controlled conditions and produce meaningful results. Considering these requirements early helps engineers specify a test bench that supports the current program and identify where flexibility may be needed for future applications.
Testing and measurement solutions for marine, non-road and heavy-duty engines.
Measurement solutions for hydrogen and ammonia engines and gas turbines.
Planning a new test bench or adapting an existing facility? Use the form below to discuss your engine configuration, measurement requirements and facility integration needs with HORIBA.
For further technical discussion and project examples, watch the Advanced Gas Turbine Testing webinar.
Do you have any questions or requests? Use this form to contact our specialists.
