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Analysis of an aircraft engine start-up process on the example of the PZL-130 TC-II „Orlik” training aircraft

Kowalski M.

Journal of KONES

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2014

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Vol. 21, No. 3

177--189

EN

The paper discloses the analysis of processes that take place during the start-up operation of the driving unit for the training aircraft of the TZL-130 TC-II Turbo-Orlik type. The aircraft is designed for selective and initial trainings at the Air Force School of “Little Eagles” in Dęblin. The driving unit comprises the PT6A-25C turbo-propeller engine from Pratt & Whitney combined with the four-bladed airscrew from Hatzell. It is specifically mentioned that data for the analysis were sourced from the S2-3a on-board recorder of flight parameters manufactured by the Air Force Institute of Technology (AFIT). The analysis was carried out both during ground and flight tests. The paper briefly outlines general structures and operation principles of typical start-up systems with the focus to their key components. Attention is paid to how important it is to select an appropriate start-up system to match the specific aircraft type and the guideline parameters for selection that should be adhered to are specified. Also there are disclosed the key mathematical relationships that are indispensable to design start-up systems and to find out their basic characteristics. It is emphasized that the start-up operation must be considered as a non-stationary process that lasts from the standstill state of the engine until the moment when the minimum required rpm is reached, sufficient to generate necessary power of the engine. In addition, the attention is paid to the fact that the value of the engine acceleration is crucial to the achievable start-up time that is deemed as one of key parameters for all start-up systems. It is demonstrated that to achieve the required level of acceleration, it is necessary to secure the so called overhead of the engine power which needs constant flow offuel and air into the combustion chamber of the engine. The last part of the paper comprises selected characteristic curves that were obtained from the analysis of the engine start-up processes both on ground and in flight. The final conclusions emphasize that the start-up system for the presented driving unit is really efficient and guarantees correct operation of the engine under any conditions.

2

Use of data from on-board data recorders for acceptance tests of avionic driving units

Kowalski M.

Journal of KONES

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2013

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Vol. 20, No. 2

201--206

EN

The paper explains how information stored in on-board recorders of flight parameters can be used for acceptance tests, also referred to as qualification tests. The disclosed example refers to the An-28 ‘Bryza’ aircraft where an old airscrew was substituted with the new generation Hartzell airscrew of the HC-B5 MP-3D type. The airscrew is an integral part of the driving system for the airscrew propelled aircraft that is provided with the TWD-10B engine. After revamping of the airscrew, the aircraft was named as TWD-10B/PZL-10S. The follow-up investigations were carried out with the aim to find out how much the airscrew substitution affected the alteration of key performance characteristics achieved by the driving unit of the aircraft. The investigations comprised both ground and in-flight tests and have led to determination of the essential characteristics for the engine operation as well as variations of the operational parameters in time. In some cases also so called phase portraits were found out for parameters of the engine operation so that to reflect dynamic properties of the engines. Such investigations are indispensable since the aircrafts are subject to operational limitations and technical conditions that must be mandatory fulfilled due to requirements of flight safety. The paper demonstrates that the data stored in on-board recorders of flight parameters can be really useful for execution of such acceptance (qualification) tests.

3

Examination of the dynamic properties of 1st stage rotor blades in one - pass engine compressors under operating conditions

Szczepanik R

Journal of KONES

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2013

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Vol. 20, No. 3

395--404

EN

This article includes studies of vibration and stress amplitudes in the Is' stage rotor blades of jet trainer one-pass engine compressors before and after refurbishment in operating conditions. The presented results were obtained using SAD-2 blade vibration amplitude registering and measuring apparatus. The same tests were carried on the same one-pass engine after modernisation. Example oscillograms from the vibration tests of the 16 blades are shown in this article, where show the vibrations of three randomly selected one-pass engines after refurbishment (marked 1, 2 and 3) out of a total of 50 engines. The engine vibration spectra cover the full rotation speed range. The difference between the vibration amplitudes of 1st stage rotor blades, in one-pass engine compressors before and after the refurbishment, is results from the difference in how the blades were attached to the disc. Before modernisation the hammer-type root was used, whereas after refurbishment dovetail-type fittings were applied. Furthermore, it was confirmed that there is nocoupling via the blade disc occurred when the blades were arranged on the disc according to the sinusoidal order of their free vibration frequencies. In such cases recorded vibration amplitudes remain within the average range (from 100 to 120 MPa in terms of stress).

4

Analysis of 1st stage compressor rotor blade stress and vibration amplitudes in one-pass jet engine

Szczepanik R.

Journal of KONES

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2013

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Vol. 20, No. 4

441--450

EN

This paper considers 1st stage compressor blade dynamics in the one-pass jet engines of trainer aircraft. Research was carried out on an engine test bench using the SAD system and its results were compared with those obtained using the tensometric approach. In this paper presented basic dynamic properties of rotor blades, bench test of rotor blade dynamics, Bench tests of the dynamic behaviour of blades subjected to external impacts and then Comparison of strain gauge and SAD tip-timing results. Then discusses the results of tests assessing the accuracy of the 1987 ITWL device by comparing strain gauge signals with those recorded by SAD apparatus in a running engine. It also presented simultaneous vibration readings of all the rotor blades at selected rotation speeds. Also shows that increased stress in these blades may be due to repeated engine surges, normal and hot engine surges, entry into the engine of a foreign object. Among others selection and layout of rotor blades in the 1st stage of a one-pass engine compressor, stress amplitudes for rotor blade, stress in rotor blade, stress amplitudes, free inlet flow and smooth engine acceleration, vibration amplitudes, asynchronous vibrations are presented in the paper.

5

Odwzorowanie fazowe prędkości obrotowej w procesie eksploatacji turbinowych silników lotniczych

Kowalski M.

Logistyka

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2009

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nr 6

CD-CD

PL

W referacie przedstawiono zagadnienia kontroli i optymalizacji układu regulacji turbinowych silników lotniczych z wykorzystaniem odwzorowania fazowego prędkości obrotowych. Wykorzystano koncepcję minimalnej liczby obserwowanych sygnałów kontrolnych oraz niejawny model matematyczny obiektu i informacji jakościowych dostępnych w odwzorowaniu fazowym prędkości obrotowej. Omawianą problematykę zobrazowano przykładami. Przedstawiono dotychczasowe korzyści wynikające z zastosowania tej metody w polskim lotnictwie wojskowym oraz wykazano możliwość jej stosowania na silnikach wielowirnikowych i dwuprzepływowych, a także uczenia systemu wraz ze wzrostem bazy danych.

EN

The paper has been intended to present some issues of checking and optimising the adjustments of aircraft gas-turbine engine controls using the technique of phase mapping of rotational speeds. Both a concept of the minimum number of test inputs and a classified mathematical model of the object together with the qualitative information available in the phase-mapping pattern of rotational speed have been used. The issues under discussion have been illustrated with several examples. The hitherto profits gained from having applied this method in the Polish military aviation have been presented. Also, capabilities have been shown to, first, apply this method to multiple-rotor gas-turbine engines and ducted-fan turbine engines (turbofans), and second, to 'teach' the system as the database gets extended.