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“What is that big golf ball doing eating that engine?!” One of the more intriguing pieces of test equipment that always generates questions when anyone sees a picture of one is the informally named “golf ball” or Inlet Control Device. MDS has a proven design for this odd-looking test equipment that is supplied to aerospace gas turbine engine developers.
Background
Certifying large civil gas turbine engines to increasingly stringent noise requirements is an important part of today’s engine development. Periodically the International Civil Aviation Organization, ICAO, updates the requirements for allowable aircraft noise levels to ever quieter targets. Certification of new large civil aircraft with modern turbofan gas turbine engines by national or regional authorities typically follows these international standards. The latest targets are called the “Stage 4” and are the latest in ever more demanding noise level requirements.
Gas turbine engines contribute a large part of the noise characteristics of an aircraft. The most significant time of operation is during landing and takeoff during which time the engines, landing gear, doors and fairings, and control surfaces including flaps all generate noise. It is thus very important for the engine manufacturers to minimize their engine noise signatures. They must be able to measure its noise performance and certify this during engine static tests prior to flight operations.
Outdoor Engine Static Testing
Testing a gas turbine engine outdoors has many advantages and uses during the developmental as well as certification phases. Specifically for noise certification of the engine, a large open arena and array of microphones for far field measurements are required. These microphones are typically arranged in an arc approximately 50m from the engine outdoor test stand and ideally any external sources of noise and reflections are minimized. The engine is then tested under conditions that accurately reproduce engine operations, especially takeoff and landing configuration, to measure and characterize the noise signature.
One unexpected aspect of outdoor static testing is that the noise characteristic of engines running in free air is higher than what is measured when on-wing in the air. It has been demonstrated that the greatest contributor to the engine noise, the fan blades, produce higher absolute noise levels on an outdoor static test stand compared to in-flight. This static test noise level is higher with the new technology higher bypass engines. It has also been determined that turbulent air reaching the fan inlet causes enough negative interaction to significantly affect the noise signature and speed stability of an engine – very undesirable effects for the engine developer trying to accurately measure the noise signature. This turbulent air is the result of unavoidable crosswinds experienced during an engine test run.
Inlet Control Device
Gas turbine engine manufacturers occasionally require a new Inlet Control Device (ICD) to meet testing needs for new engine ranges or outdoor test stands. MDS has supplied a number of these ICDs and understands the technology behind the sizing and operation of this very specialized test hardware. MDS can also customize the device to meet additional technical requirements specific to each application.
The ICD helps to control the turbulent flow of air into the engine bellmouth by smoothing and normalizing the flow in front and around the engine. This is accomplished by having the air flow through a spherical screen that is supported by a geodesic structure dome several metres in diameter. The incoming air enters through numerous holes of a steel plate and then is straightened by an aluminum honeycomb panel several centimetres thick. The air being sucked into the engine inlet is then able to flow nicely and without turbulence.
The ICD is designed to work in winds of up to 5m/s which will allow the user to test in a variety of wind conditions while not losing too many testing opportunities. The ICD allows winds from numerous directions: side, front and rear.
Inlet Velocity Vectors ICD with Wind At 5m/s
Each device is sized for the expected range of similar sized engines; at a certain point a separate ICD may be required if the engine difference is too large. The size is a function of the engine bellmouth inlet diameter and how it fits around the fixed test stand. The structure used to support the dome is sealed to the engine body with a flexible sail cloth that also prevents unwanted airflow from the rear of the engine reaching the bellmouth inlet.
Now that the airflow to the engine has been controlled to improve the inlet conditions and thus better represent in flight operation, it must be remembered that the prime goal is to be able to perform noise characterization testing for the purposes of certification. In order to do this, MDS has designed the ICD to also minimize the acoustic blockages: the perforated steel plate, thin aluminum honeycomb, and minimal frame structure allow as much noise to reach outside as possible. The 246 separate frames (typical) of the geodesic dome also help to create a close-to-spherical shape.
Prior to its first use, the owner must calibrate the acoustic signature of the ICD by placing a known source of noise inside the dome in position at the test stand. The noise level at different frequencies is then measured using special microphones set up in a 45 degree arc and 50m from the test stand. This is the same measurement equipment being used for eventual noise certification of each engine. These calibration results are then used for all future testing.
MDS is always pleased to offer the option of customizations and additional optional features. As a way to accommodate different engine configurations, the ICD structure may be constructed with an inbuilt forward tilt, as well as the capability to adjust it backwards and forwards. Another feature that can be added is to use the support legs to raise the device by up to 1m (or more) to account for different engine horizontal centerlines when hanging on the test stand. For inspection purposes, an access panel can be installed and combined with a small working surface inside the fragile dome for a single person. Also, typically a number of sensors are attached to the ICD to measure temperatures and pressures during tests.
This past spring, Kevin Fitzgerald, MDS Aero Support’s President and CEO, led the company in a campaign to raise money for The Ottawa Hospital’s White Coat Campaign. The White Coat Challenge inspires local Ottawa businesses to raise money to purchase the latest life-saving technology for The Ottawa Hospital Cancer Centre and to provide superior care to those suffering from cancer. The employees of MDS Aero raised a remarkable $32,706 that allowed the Centre for Innovative Cancer Research to buy an ultra-low temperature freezer to store cancer cells and two DNA spinners to isolate DNA from cancer cells. Both devices will help The Centre for Innovative Cancer Research develop new therapies, efficiently run experiments, and conduct research on cancer cells. “We wanted to do something where people could make a real difference”, said Kevin Fitzgerald. “We were worried about donor fatigue, but the whole company got on board. It’s important for us to give back to the community after 25 years in business”. MDS exceeded the initial target of $25,000 that was set to commemorate MDS’s 25 year anniversary that was celebrated in 2010.
*Picture: To honour the achievements of MDS Aero’s inaugural White Coat Campaign, Kevin Fitzgerald, President and CEO, and Elizabeth MacLeod, Office and Human Resource Manager, (both in centre) were presented with White Coats, an symbol of accomplishment in many medical schools.
10 Steps to a Successful Employee Campaign
(courtesy of The Ottawa Hospital Foundation)
For more about the White Coat Campaign at The Ottawa Hospital, please see:
http://www.ohfoundation. ca/tools/workplace/Workplace_Campaign_equipmentlist.pdf
MDS teamed up with Hanwha Corporation, one of the biggest conglomerates in Korea, to build one of the world’s largest Altitude Engine Test Facilities (AETF) for The Korean Agency for Defence Development (ADD) in Seosan, Chungcheongnam-do, South Korea. MDS provided the engineering and design expertise, as well as the data acquisition systems and thrust measurement system, while Hanwha procured and installed the new equipment for this project and handled all civil works; both companies were involved in commissioning the facility.
The AETF is a large multipurpose test facility and it is able to perform Direct Connect (DC) engine tests and Freejet (FJ) engine tests. The DC test simulates the altitude and the speed operation environment at the engine intake and around the engine with and without engine afterburner. In this mode, the facility can test engines with mass flow rates up to 110 kg/s. The FJ type tests the engine with a supersonic aerodynamic nozzle to simulate altitude/speed conditions in front of the engine intake with different angles of attack. The facility is exceptional in that it can simulate engine operation conditions with an altitude of up to 20 km and a Mach number up to 3.4. In addition to the two modes discussed, the AETF was designed to operate at various conditions ranging from sea level to closed-loop vacuum.
The test cell (door open and door closed)
We asked some of MDS’s key players in this project some general questions about the facility as well as some questions regarding the significance of the project and the challenges that were faced during design and installation of the AETF. The individuals who were interviewed included: Dionne Barwise, the Project Manager; Dennis Stang, the lead Instrumentation and Controls Engineer; Dr. Yakov Kabakov, the Lead Aerodynamicist on the project; and Martin Gratton, the Vice-President of Engineering at MDS.
The settling chamber
What was the biggest cultural challenge?
Language was the biggest issue for both parties while working on this project. To overcome these obstacles, written communication as well as drawings and sketches became very important. Despite the language barrier, MDS and Hanwha worked together to forge a positive working relationship by establishing methods of communication that satisfied both parties, which ultimately allowed us to accomplish this amazing achievement together.
– Dionne Barwise, Project Manager
Why was MDS chosen to carry out and build this facility?
The project was primed by Hanwha Corporation, a large industrial Korean company. By partnering with MDS, Hanwha was able to bring the necessary international expertise to the table. Hanwha/MDS were awarded the project based on MDS’s superior understanding of what it takes to build such a facility. The project was won in an open competition and public tender which awarded points that were heavily weighted towards the best technical solution. – Martin Gratton, Vice-President, Engineering
What does this project mean for MDS?
Altitude facilities of this size and capabilities are rarely built, with none other having been built in the last 25 years. This project not only highlights MDS’s ability to design such a sophisticated facility, but positions the company well to participate on similar projects to replace or upgrade similar but aging altitude facilities around the world. In other words, this is a huge feather in MDS’s cap, one that will hopefully lead to similar projects in the future. – Martin Gratton, Vice-President, Engineering
What does this mean from an engineering perspective?
This was a project that made full use of our engineering capabilities, including aerodynamics, acoustics, instrumentation, controls, mechanical design, and the list goes on. The aerodynamic design alone required that the compressors, exhauster, and all components and branches be simulated in order to determine the flight conditions in the altitude chamber. Those calculations drove the designs of the many large components like the heater, water cooled diffuser, heat exchanger, settling chamber, bypass bleeds, compressors and exhauster. Therefore from an engineering perspective, this was one of the most complex projects ever tackled by MDS.
– Martin Gratton, Vice-President, Engineering
Dennis Stang in the
Instrumentation Room
How did you handle multiple control valves feeding and removing air from the test cell and settling chamber?
The control system was designed with valve priority so that once pressures and flows were in the desired test condition, only one valve was controlling pressure in the settling chamber and another valve was controlling altitude in the test cell. If these valves moved to full open or full close, other valves would take over control, maintaining test conditions in a safe manner.
– Denis Stang, Lead Instrumentation and Controls Engineer
There were many technical challenges on this project but the top three were:
- The definition and specification of the Compressor/Exhauster Station;
- The aerodynamic design of the test cell inlet section including settling chamber, FJ nozzle, and engine bellmouth; and
- The design on the aerodynamic P&ID which had to satisfy the requirements for testing engines at various steady state and transient modes.
– Dr. Yakov Kabakov, Group Leader Aerodynamics and Noise Control
When asked what aspect of the project Dr. Yakov Kabakov was most proud of, he responded, “First, to be part of the team that built this remarkable facility was a tremendous experience. This is the largest facility of its kind to be built within the last 25 years. Second, the operational performance of the facility is exactly as predicted. Based on the complex nature of the facility this is not a trivial accomplishment.”
Dionne Barwise & Dr. Yakov Kabakov at the facility in Korea
In June 2011, MDS and the National Research Council of Canada presented at the SAE 2011 International Conference on Aircraft and Engine Icing and Ground Deicing in Chicago, Illinois. The conference was for those in the industries of aerospace, aviation, and meteorology to discuss safe flight and operations in icing conditions. Simulation, protection, detection, fluids, training, and regulatory practices related to engine icing and ground deicing were the main topics of papers and presentations that were submitted.
John Jastremski, Vice President of Sales and Marketing at MDS, and James MacLeod of the National Research Council of Canada (NRC) presented information on the development of a unique icing spray system. The system was designed for use in a new icing test facility in order to meet large engine testing requirements. The facility, known as The Global Aerospace Centre for Icing and Environmental Research (GLACIER), was built in partnership with the NRC, Pratt & Whitney Canada, and Rolls-Royce Canada for icing testing and certification of aviation gas turbine engines.
Glacier is a direct connect icing tunnel configuration, with a spray mast located inside the tunnel. The system produces a realistic cloud of water droplets by injecting water into the airstream using pneumatic spray nozzles. The size of the water droplets is a function of the water flow, air pressure ratio, and the spray nozzle design. The atomizing of the water by the spray nozzle can be manipulated to yield water droplets with known diameters. An icing cloud is the result of the temperature in the tunnel being below the freezing point of water, causing the droplets to supercool.
The design of the spray system evolved from knowledge acquired by the NRC, who have been developing spray systems for close to 70 years. However, since Glacier is a large outdoor test facility, there were certain aspects of the application that made the design difficult. Firstly, previously designed tunnel equipment had to be recreated on a much larger scale. Secondly, supporting equipment (other systems) had to be in place to protect the spray system for operation in extremely low temperatures. A heating system was implemented to prevent the water from freezing inside the various components during operation, idle, and shutdown.
The criteria used to create the spray system included: airflow capacity, water control and air control systems, spray nozzle type, nozzle spacing, nozzle calibration, spray bar heating, flow blockage, engine diameter, droplet size range, liquid water content, humidity correction, operating temperature range, and spray uniformity.
Future upgrades to this system include ice crystal generation, which will be required to comply with new regulations currently being evaluated by the airworthiness regulatory agencies.
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Posted by Elyse Moody |
Air France Industries KLM Engineering & Maintenance broke ground on a 5,000-sq.-meter test cell facility for what it dubs Very Big Engines, or VBE, at Paris-Charles de Gaulle in April. The site still is being excavated, but here’s how AFIKLM E&M plans for it to look.
[All photos: AFIKLM E&M]
The test cell, supplied by MDS of Canada, will accommodate GE90-94/115, CFM56-5C and GP7200 engines. But Anne Brachet, senior VP of engine overhaul for the company, tells me today that it also will induct future engines — potentially the Trent XWB and GEnx. The MRO’s next move depends on what Air France/KLM decides to do, she says. But undoubtedly, she’s planning to do new engines — both testing and overhaul — either at Orly, the Constellation site at CDG or in Amsterdam.
To see full article go to: AVIATION WEEK’S aftermarket blog
Visit MDS at the Dubai Airshow, the foremost aerospace event in the Middle East. The show will be running from November 13-17, 2011 at the city’s Airport Expo. We will be exhibiting at booth E217, located in the Canadian Pavillion.
We look forward to the opportunity to discuss the latest technologies in aviation engine testing, MDS’ products, and worldwide services. If you wish to arrange a meeting or obtain more information, please contact Simon Arbuthnot, Vice President, Business Development or Joe Hajjar, Manager, Systems Engineering.
Simon Arbuthnot Joe Hajjar
MDS Aero Support Corporation MDS Aero Support Corporation
Phone: +1 613-744-5794 ext 464 Phone: +1 613-744-5794 ext 311
Mobile: +44 (0) 7791-134566
joe.hajjar@mdsaero.com
simon.arbuthnot@mdsaero.com
Visit MDS at the International Aviation and Space Salon being held at Ramenskoye Airfield in Zhukovsky, Moscow Region, Russia from August 16 – 21, 2011. We are exhibiting at Hall F3, Booth #36 which is the Canadian Pavilion.
We look forward to the opportunity to discuss the latest in gas turbine engine test facility and test systems design and supply. For more information or to arrange a meeting, please contact Simon Arbuthnot, Vice President, Business Development, or Konstantin Ilchenko, Regional Director Russia & CIS Countries:
Simon Arbuthnot Konstantin Ilchenko
MDS Aero Support Corporation MDS TurboTest
Phone: +1 613-744-5794 ext 464 Phone: +7 4855.25.0995
Mobile: +44 (0) 7791-134566 Mobile: +7 905-131-7440
