On the heat inleak into the airflow impact on the mode parameters changing prior to the inlet to the bypass turbojet engine while tests in the thermal pressure chamber by the scheme with the attached pipeline

Aeronautical and Space-Rocket Engineering


DOI: 10.34759/vst-2022-3-143-157

Аuthors

Klinskii B. M.

e-mail: bmklinskiy@ciam.ru

Abstract

The most common scheme of bench tests of an aviation gas turbine engine in the test stand box or on an open test stand is a layout, which includes a test-bench input device with a lemniscate headpiece.

When the turbofan engine testing in the thermal pressure chamber, an inlet connected pipeline or inlet device with a lemniscate headpiece (testing scheme “with a baffle”) is being employed. Such inlet devices include a flow rate metering manifold for measuring air mass flow rate, which measuring section is set at a relative distance of not less than 1.5 gauge (L/D) from the inlet to the tested turbofan engine according to the requirements of the Industry Standard OST 1 02555-85.

When conducting turbofan engine tests in the thermal pressure chamber of the high-altitude test bench under both climatic and altitude-velocity conditions by the scheme with the connected pipeline at the inlet, as well as at the autonomous low-pressure fan testing on the compressor test bench with the air heating or cooling at the inlet, the heat inleak forming to the subsonic flow at the turbofan engine inlet (or it removal) is possible.

The process of the flow energy additional increase (decrease) while heat input (removal) leads the thermal boundary layer forming in the in the cross section of the mass air flow meter and at the engine inlet. It leads as well to the change of regime parameters values (total pressure p*lN and total temperature T*IN ) at the inlet to the turbofan and to their certain difference from the corresponding values of p*M and T*M, measured according to the OST 102555-85 from the inlet section into the air flow manifold at a relative distance of at least LM-M÷IN-IN/DM≥ 1,5.

However, for the turbofan engine with high bypass ratio, mode parameters measuring in front of the engine (p*IN (Pa), T*IN (K)) is difficult to ensure under bench conditions for a number of reasons:

– due to the absence of fan inlet guide vanes for a low-pressure fan of a turbofan engine, which moght be employed for measuring values of (p*IN, T*IN) ;

– owing to the possibility of resonance stresses occurrence in the fan working blades while installing radial chasers for p*IN, T*IN measuring nearby in front of them in the inlet bench channel.

Neglecting accounting for the heat inleak (or heat removal) as applied to the turbofan engine with the large degree of bypass and reduced fan pressure rise degree may, in some cases, lead to noticeable errors in the turbofan engine basic data estimation. It relates,in particular, to the fan efficiency value, as well as the values of the turbofan basic parameters reduced to the international standard atmosphere.

The article recounts the technique for determining the values of regime parameters of breaking temperature T*IN and total pressure p*IN directly at the inlet of the turbofan engine of high degree of bypass. This technique accounts for the heat inleak (removal) to the airflow in the pipeline, attached to the engine in the section between the measuring section in the flow manifold and the section prior the engine inlet, by reference to the condition of mass air flow rate value preserving GAIR.M=GAIR.IN and accounting for heat line of ΔE in the total flow energy value of EIN =EM + ΔE at the turbofan inlet.

The article presents the examples of the heat supply effect (or heat removal) on the nature of the thermal boundary layer changes in the flow measuring section of the inlet pipeline by the results of tests of turbofan engine under thermal vacuum chamber in the altitude-speed conditions. The example of estimating the value of the heat flux to the airflow and the corresponding change in the main regime parameters at the inlet to the turbofan engine of high bypass ratio is recounted.

Keywords:

bypass turbofan engine, thermal PRESSURE chamber, test bench box, compressor test bench, attached inlet pipeline, flow rate metering collector

References

  1. Dvigateli gazoturbinnye aviatsionnye. Terminy i opredeleniya. GOST 23851-79 (Avia gas turbine engine. Terms and definitions, State Standard 23851-79), Moscow, Standarty, 1980, 100 p.

  2. Ispytaniya aviatsionnykh gazoturbinnykh dvigatelei. Terminy i opredeleniya. OST 1 02525-84 (Tests of aviation gas turbine engines. Terms and definitions. Industry Standard 1 02525-84), Moscow, FGUP NIISU, 1985, 10 p.

  3. Grigor’ev V.A., Gvisharov A.S. (ed) Ispytaniya aviatsionnykh dvigatelei (Tests of aviation gas turbine engines), Moscow, Innovatsionnoe mashinostroenie, 2019, 541 p.

  4. Sovershenstvovanie metodov i sredstv ispytanii aviatsionnykh GTD i gaogeneratorov. Sbornik statei, Trudy TsIAM, no. 1361, Moscow, Pero, 2019, 254 p.

  5. Sistema izmereniya raskhoda vozdukha s kollektorom na vkhode aviatsionnykh GTD pri stendovykh ispytaniyakh. Obshchie trebovaniya. OST 102555-85 (An air flow measurement system with a collector at the entrance of an aviation gas turbine engine during bench tests. General requirements. Industry Standard 102555-85 Moscow, FGUP NIISU, 1988, 14 p.

  6. Vulis L.A. Termodinamika gazovykh potokov (Thermodynamics of gas flows), Moscow, Leningrad, Gosenergoizdat, 1950, pp. 52-58.

  7. Kazadzhan P.K., Tikhonov N.D., Yanko A.K. Teoriya aviatsionnykh dvigatelei (Theory of aircraft engines), Moscow, Mashinostroenie, 1983, 222 p.

  8. Korovin B.B. Dvigateli, 2012, no. 4(82), pp. 12-14.

  9. Peshekhonov N.F. Al’bom priborov izmereniya davleniya, temperatury i napravleniya potoka v kompressorakh (Album of instruments for measuring pressure, temperature and flow direction in compressors), Moscow, TsIAM, 1992, 52 p.

  10. Efimov P.I. Aviatsionnye pribory (Aviation devices), Ulyanovsk, UlGLU, 2018, pp. 94-96.

  11. Atmosfera standartnaya. Parametry. GOST 4401-81 (Standart atmosphere. Parameters. State Standard 4401-81), Moscow, Standarty,1981, 180 p.

  12. Litvinov Yu.A., Borovik V.O. Kharakteristiki i ekspluatatsionnye svoistva aviatsionnykh turboreaktivnykh dvigatelei (Characteristics and operational properties of aviation turbojet engines), Moscow, Mashinostroenie, 1979, pp. 150-156.

  13. Klinskii B.M. Determining test-bench box aerodynamics impact on the force from the gas turbine engine thrust by layout changing of the inlet lemniscate mouth piece. Aerospace MAI Journal, 2021, vol. 28, no. 4, pp. 163-179. DOI: 10.34759/vst-2021-4-163-179

  14. Gosudarstvennaya sistema obespecheniya edinstva izmerenii. TERMOPARY. Nominal’nye staticheskie kharakteristiki preobrazovaniya. GOST R 8.585-2001 (State system for ensuring the uniformity of measurements. Thermocouples. Nominal static characteristics of conversion. State Standard R 8.585-2001), Moscow, Standartinform, 2010, 81 p.

  15. Abramovich G.N. Prikladnaya gazovaya dinamika v 2 ch. (Applied gas dynamics: In 2 parts), Moscow, Nauka, 1991. Part 1, pp. 276-282.

  16. Kreith F., Black W.Z. Basic heat transfer, New Уork, Harper & Row, 1980, 556 p.

  17. Mikheev A.A., Mikheeva I.M. Osnovy teploperedachi (Fundamentals of heat transfer), Moscow, Energiya, 1977, 344 p.

  18. Borisenko A.I. Gazovaya dinamika dvigatelei (Gas dynamics of engines), Moscow, Oborongiz, 1962, pp. 397-403.

  19. Hilkevich V.Ya. An influence of temperature non-uniformity for input stream on a nozzle performances. Aerospace MAI Journal, 2009, vol. 16, no. 4, pp. 27-31.

  20. Soeder R.H. and Mehalic C.M. Effect of Combined Pressure and Temperature Distortion Orientation on High-bypass-ratio Turbofan Engine Stability, NASA TM-83771, 1984, 37 p.

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