Altitude Engine Test Facility Research Articles

지상 및 고도 모사 입구 압력조건에서의 마이크로 터보젯 엔진 성능시험평가 연구

The present study investigated the performance of micro turbojet engine experimentally at various engine inlet pressure conditions, which covers the altitude up to 3.0 km. A test rig for engine performance measurements was built and installed in the altitude engine test facility located in Korea Aerospace Research Institute, and the performance tests were conducted under the altitude conditions obtained by reducing the engine inlet pressure. In this study, commercially available micro turbojet engine, Jetcat P300-RX, was used and the performance parameters, such as thrust, fuel flow rate, exhaust gas temperature, were measured for various PLA conditions at altitude simulating inlet pressure values. The results showed that as the inlet pressure becomes reduced, which means the altitude increases, the thrust and fuel flow rate of the engine decreases monotonously. For example, the thrust is 257.7N at sea level condition while it decreases to 183.7N at 3.0 km altitude condition. When the corrected performance parameters are introduced, those corrected values present single curve regardless of operating conditions. Those results will be used as the reference data not only for performance improvement of the component but also for indigenous engine development program.

Assessment of the air flowrate measurement in altitude engine tests by the national measurement standards system

The air flowrate in the engine inlet is an important parameter used to calculate common performance metrics such as the thrust and specific fuel consumption of a gas turbine engine. In the Korea Aerospace Research Institute (KARI) altitude engine test facility, air flowrates are calculated by measuring the static pressure, total pressure and temperature in an engine inlet duct. In the present study, in order to verify the air flowrate measurements at the engine inlet duct of the KARI altitude engine test facility, inlet flow measurement devices which are a total pressure rake, total temperature rake, and boundary layer rake were tested in the national measurement standards system for high pressure gas flow of the Korea Research Institute of Standards and Science (KRISS). Sonic nozzles, calibrated for flows rate up to 10000 m3/h and pressure range up to 50 bar (with an uncertainty = 0.18 %), were used as reference meters. We compared the air flowrates obtained by the area-weighted average duct Mach number in the inlet flow measurement devices of the KARI engine inlet duct to the reference flowrates of sonic nozzles at KRISS up to a Mach number of 0.15.

Performance Evaluation of a Rake Used for Measuring Total Pressure and Total Temperature Inside an Engine Inlet Duct

The Korea Aerospace Research Institute runs the ground-based Altitude Engine Test Facility (AETF) for simulating high-altitude environments. This facility is widely used to test the performance of gas turbine engines at ground level to high altitudes. When engine performance is tested in the AETF, total pressure and total temperature of airflow can be measured using rakes in a duct directly connected to the engine inlet. The total pressure and total temperature of airflow into an engine are the main factors affecting the thrust and specific fuel consumption rate of the engine. Furthermore, the total pressure and total temperature at the engine inlet are used as the main reference values when operating test equipment to determine the airflow rate and temperature corresponding to the performance test conditions of the engine. The performance evaluation of the rake used to measure this is crucial. Accordingly, in this study, to improve the accuracy of the total pressure and total temperature values measured using rakes, their total pressure coefficient and total temperature recovery factor are measured, and the measurement uncertainty of the total temperature recovery factor is evaluated.

다점 피토관을 이용한 기체 유량 측정의 불확도 평가

ABSTRACT Gas flow measurement in a closed duct was performed using multi-point Pitot tubes. Measurement uncertainty was assessed for this measurement method. The method was applied for the measurement of air flow into a gas turbine engine in an altitude engine test facility. 46 Pitot tubes, 15 total temperature Kiel probes and 9 static pressure tabs were installed in the engine inlet duct of inner diameter of 264 mm. Five tests were done in an airflow range of 2~10 kg/s. The flow was compressible and the Reynolds numbers were between 450,000 and 2,220,000. The measurement uncertainty was the highest as 6.1% for the lowest flow rate, and lowest as 0.8% for the highest flow rate. This is because the difference between the total and static pressures, which is also related to the flow velocity, becomes almost zero for low flow rate cases. It was found that this measurement method can be used only when the flow velocity is relatively high, e.g., 50 m/s. Static pressure was the most influencing parameter on the flow rate measurement uncertainty. Temperature measurement uncertainty was not very important. Measurement of boundary layer was found to be important for this type of flow rate measurement method. But measurement of flow non-uniformity was not very important provided that the non-uniformity has random behavior in the duct.

헬리콥터용 보조동력장치 고공성능에 관한 실험적 연구

An APU(Auxiliary Power Unit) for helicopters has been developed in Korea and tested at the AETF(altitude engine test facility) in KARI(Korea Aerospace Research Institute) for the purpose of the military qualification. A cell correlation test was performed before the official test, and the results are within the tolerance. The APU has the capability of supplying electric power as well as compressed air to the helicopters. It was tested at bleed extraction conditions, electric power extraction conditions, and maximum continuous concurrent power conditions within the entire helicopter flight envelop. Some special test equipments were implemented for the measurement of air flowrate, electric power and so on. The tests were successfully performed and their results satisfy the requirements of the helicopters.

가스터빈 엔진용 공기터빈 시동기 성능에 관한 실험적 연구

Gas turbines for an aircraft have the start and restart capabilities within their flight envelop. It is an important item for engine qualification and substantiated with the test. Experimental investigations were carried out to find the relation between the corrected torque and the corrected rotating speed of an air turbine starter in this study. A dedicated air supply system for the air turbine starter and a special device to measure the torque and the rotating speed of the air turbine starter were developed and installed at the altitude engine test facility in Korea Aerospace Research Institute. Experimental results show that the relations between the corrected torque and the corrected rotating speed of the air turbine starter are linear and the inlet temperature and pressure conditions for the air turbine starter were found out to provide minimum required torque for the engine qualification test at various altitude. The start and restart tests for the currently developing engine were successfully performed using this experimental results.

Optimal design of supersonic nozzle contour for altitude test facility

This paper develops a robust and practical design for supersonic nozzles to be used in an altitude engine test facility. Although many studies have been conducted on nozzle design, none of these present a robust yet practical and simple method for designing supersonic nozzles. This research attempts to develop such design for supersonic nozzles by combining method of characteristics (MOC), optimization algorithm, and computational fluid dynamics analysis for design verification. Preliminary design optimal techniques were adopted to reduce nozzle length while keeping the exit area constant in the design. Optimization produced a smooth flow by generating a parallel and uniform flow at the exit. A two-dimensional model was initially used because of the axisymmetrical characteristic of the flow in this study. The optimal nozzle was designed for the operation of a test facility at Mach number 2.3 and altitude of 7 km. The optimal design produced a uniform and parallel flow at the given test condition.

Development of Block type Inlet Distortion Simulating Device for Gas Turbine Engine Inlet Distortion Test

In late 1960's, engineers of the engine manufacturer experienced that the distortion of inlet flow of turbofan and turbojet engine could cause the surge in compressor and affect overall engine operational performance, which result in the deterioration of stability of the engine. In this study, block type of inlet distortion simulating device has been developed in order to investigate the effect of inlet distortion on the deterioration of overall engine operational performance. The inlet distortion simulating device was installed in front of engine inlet in order to simulate distortion of inlet flow. The degree of inlet distortion was measured by rakes installed upstream the inlet distortion simulating device and between the engine inlet and inlet distortion simulating device. Before applying the inlet distortion simulating device to real engine, preliminary tests were performed with a simulated engine in order to verify the degree of inlet distortion by the device. Preliminary inlet distortion tests were performed in Altitude Engine Test Facility(AETF) of Korea Aerospace Research Institute(KARI) and results showed that the inlet distortion simulating device could be used in simulating various inlet distortion cases.

가스터빈엔진 고공성능시험설비의 측정불확도 개선

An Altitude Engine Test Facility(AETF) was built at the Korea Aerospace Research Institute in October 1999 and has been being operated for altitude testing of gas turbine engines of 3,000 Ibf class or less. The AETF has been calibrated using several engines such as 169 of Teledyne Co. as a facility checkout engine. Uncertainty analyses on the air now rate and thrust were performed using the test results, according to ASME PTC 19.1-1998. Several modifications on the facility and test method were made in order to improve the measurement uncertainty to a satist:1ctory level over the whole operating envelop. Spatial distributions of pressure and temperature were measured, sensors were substituted by more accurate ones, inlet duct was modified to refine the flow quality, and pressure control logic was revised to remove the cell pressure fluctuation. As a result. the uncertainty of the air flow measurement was improved by 0.1 % over all the test conditions. and the net thrust measurement by up to 3%. The improved measurement uncertainties of air now and thrust are 0.68-0.73% and 0.4-1.3%, respectively.<br/>

소형 터보제트 엔진 시험 및 불확도 분석

The Altitude Engine Test Facility(AETF) was built at the Korea Aerospace Research Institute and has been being operated for the gas turbine engines in the class of 3,000 lbf thrust. To enhance the confidence level of AETF to the international level, a series of studies and facility modification have been conducted to improve the measurement uncertainty and reliability. In this paper, some part of the facility evaluation tests performed with a single spool turbojet engine are introduced. Tests were performed simulating the flight conditions as steady state, sea level for various flight speeds (i.e., Mn

가스터빈엔진 천이 성능 시험에 의한 정상상태 성능 예측

항공기용 가스터빈엔진에 대한 경제적인 시험 기법 개발을 위해 천이상태 성능 시험 결과로부터 정상상태 성능을 예측할 수 있는 방안을 모색하였다. 천이상태 성능과 정상상태 성능이 상이한 원인을 동역학적 천이 효과, 열적 천이 효과, 공기역학적 천이 효과로 구분하고, 각각을 모델링해서 엔진의 천이상태 성능을 통해 정상상태 성능을 계산하는 보정 인자를 정량화 하였다. 엔진 성능시험은 한국항공우주연구원이 보유한 고공환경시험설비에서 이루어졌다. 먼저 천이상태 성능시험 시 나타나는 엔진 입 출구의 온도 변화가 엔진 성능에 미치는 영향을 보정했으며, 그 후 도입된 보정 인자를 사용해 정상상태 성능을 예측하였다. 이렇게 예측된 결과와 실제 정상상태 성능시험 결과를 비교한 결과, 연료 소모량의 차이 3.68% 이내로 정상상태 성능을 예측할 수 있어, 본 연구에서 사용한 보정 기법이 상당한 정도의 정확도를 보장하고 있는 것으로 나타났다. Methodology of predicting steady performance of gas turbine engine from transient test data was explored to develop an economic performance test technique. Discrepancy of transient performance from steady performance was categorized as dynamic, thermal and aerodynamic transient effects. Each effect was mathematically modeled and quantified to provide correction factors for calculating steady performance. Engine performance tests were conducted at Altitude Engine Test Facility of KARI. The influence of engine inlet/outlet condition change on engine performance was corrected firstly, and then steady performance was predicted from the correction factors. The result was compared with steady performance test data. This correction method showed an acceptable level of precision, 3.68% difference of fuel flow.