Yardımcı donanımların motor gürültüsüne etkisinin deneysel olarak incelenmesi
Experimental investigation of the effect of auxiliary equipment on the engine noise
Yazar: ERCAN BOZTEPE
Danışman: PROF. DR. İSMAİL AHMET GÜNEY
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Makine Mühendisliği Ana Bilim Dalı / Makine Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2018
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
Gün geçtikçe teknolojinin ilerlemesiyle birlikte müşteri beklentileri de değişime uğramaktadır. Bu durum üreticileri, üretilen ürünlerin müşteri beklentilerine göre yeniden tasarlanmasına zorlamaktadır. Özellikle otomotiv dünyasında bu duruma sıkça karşılaşılmaktadır. Ortalama olarak iki üç yılda bir üretilen araçlarda major değişikliğe gitmelerinin ana sebebini bu durum oluşturmaktadır. Yapılan anketler ve pazardaki ekonomik durumlarda yaşanan değişimlerin, otomotiv üreticilerini her zaman daha iyisine ulaşmak için çalışmalar yapılmasına zorlamaktadır. Yapılan iyileştirmelerin en önemli kısımlardan biri de NVH alanında yapılan çalışmalardır. NVH açısından ise motor gürültüsü en önemli parametreyi oluşturmaktadır. Motor gürültüsünün hangi komponentlerden kaynaklandığını bilmek motor gürültüsü azaltma çalışmalarında nokta atışı yapmayı sağlayacaktır.
İçten yanmalı motorların oluşturmuş olduğu titreşim ve gürültü araç seyir konforunu etkilemektedir.  İçten yanmalı motorların sebep olduğu gürültüler genel olarak üç bölümden oluşmaktadır. Bunlar mekanik, yanma ve yardımcı ekipmanlardan kaynaklı gürültü olarak öne çıkmaktadır. Bu tez kapsamında yardımcı ekipmanların motor gürültüsüne etkisi incelenmiştir.
Tez kapsamında ilk olarak ses, gürültü ve titreşimle ilgili bilgiler verilmiştir. Daha sonra taşıtlarda meydana gelen gürültü ve titreşimlerin yayılma yöntemlerinden bahsedilmiştir ve motor gürültüsünün zamanla azaltılmasıyla ilgili istatiki bilgiler verilmiştir.
Tez kapsamında 12.7 litre 505PS gücünde ticari bir motorun yarı anekoik odada dinamometreye bağlanarak motor yardımcı elemanlarının  x, y ve z yönündeki titreşim ve motorun sağ, sol, yan ve üst noktalarından 1m uzağına yerleştirilen mikrofonlardan alınan gürültü datası motorun tam yük, sıfır yük ve rölanti devri koşullarında toplanmıştır. Motor yardımcı donanımlarından motorun sol tarafında bulunan yağ filtresi, su pompası, yağ tankı ve turbo ile motorun sağ tarafında bulunan alternatör, yakıt filtresi, emme manifoldu, yakıt hattı, yakıt pompası, marş motoru ve yağ tankının motor gürültüsüne olan katkısı incelenmiştir. İncelenen gürültü datasında motorun hangi yönündeki gürültünün baskın olduğu ayrıca bu yöndeki hangi komponentin hangi motor çalışma koşullarında daha baskın olduğu incelenmiştir. Her bir komponente motor üzerindeki konumundayken modal analiz testi gerçekleştirilerek komponentlerin hangi frekanslara daha duyarlı olduğu diğer bir deyişle doğal frekansları bulunmuştur.
Motorun sol ve sağındaki baskın gürültüyü oluşturan merkez frekanslar belirlenmiştir. Bu merkez frekanslar %20 band genişliğinde kesilerek motor komponentlerin ivme değerleri motorun tam yük koşullarında 800 dev/dak'dan 2100 dev/dak'ya kadar hızlanarak alınan datalar incelenmiştir. İncelen bu ivme değerlerinden hangi komponentin hangi motor devrinde daha baskın geldiği bulunarak motorun baskın olan gürültü kaynağı tespit edilmiştir. Tespit edilen gürültüler akustik kamera kullanarak, akustik kameranın motor gürültüsü kaynağı tespitinde hangi frekanslarda daha efektif olduğu incelenmiştir.
Tez kapsamında bulunan sonuçlar;
•	Tam yük koşullarında motorun sağ tarafından kaynaklanan gürültü tüm motor devirlerinde daha baskındır.
•	Sıfır yük koşullarında ise 1750 dev/dak'ya kadar motorun sağ ve sol tarafındaki gürültü seviyesi aynı 1750 dev/dak'dan sonra sağ yüzeyindeki gürültü seviyesi daha  baskın hale gelmektedir.
•	Motorun rölanti devrinde ise sol yüzeyindeki gürültü seviyesi en yüksektir.
•	Akustik kameranın motor gürültüsü kaynağı tespitinde düşük frekanslarda doğru sonuç vermediği görülmüştür.
•	Motorun sol tarafındaki gürültünün 1000Hz ve 2000Hz arasında yağ filtresinden kaynaklandığı görülmektedir.
•	Motorun sol tarafındaki gürültünün 1000Hz'den düşük frekanslarda yağ tankı ve turbodan kaynaklandığı görülmektedir.
•	Motorun sağ tarafındaki gürültünün yüksek frekanslarda baskın olan kaynağın yakıt filtresinden kaynaklandığı görülmektedir.
•	Motorun sağ tarafındaki gürültünün düşük frekanslarda baskın olan kaynağın alternatörden kaynaklandığı görülmektedir.

Abstract:
As the day passed, with the advancement of technology, it is observed that customer expectations are changing in parallel with the advancement of technology. As it is known, products that are produced ultimately aimed to sell customers. Therefore, modifications are made to products produced from time to time due to changes in customer expectations. Especially in the automotive world, this situation is frequently encountered. This is the main reason for the major change in vehicles produced on average every two to three years. Questionnaires and changes in the economic situation in the market force automotive producers to always work to get better. Some of the most important parts of the improvements are work done in NVH area. In terms of NVH, engine noise is the most important parameter. Knowing which component of engine noise is most important to will allow you to make a point shot during engine noise reduction operations.
The vibration and noise generated by the internal combustion engines affect the ride comfort. The noises caused by internal combustion engines generally consist of three parts. These stand out as noise caused by mechanical, combustion and auxiliary equipment. In this thesis, the effect of auxiliary equipment on motor noise in examined. 
Within the scope of the thesis, firstly information about noise and vibration was given. Later on, the methods of propagation of the noise and vibrations that occur in the vehicles are mentioned and statistical information about the reduction of engine noise over time is given.
Within the scope of thesis, a commercial engine at 12.7 liter 505PS power is connected to a dynamometer in semi-aneochoic chamber and  vibration data from the accelerometer placed in the x, y, and z directions of motor auxiliaries and noise data from the microphone placed  1m away from right, left, side and top points of engine are measured under full load, zero load and idling conditins collected. On the left side of engine, engine auxiliary equipment includes oil filter, water pump, oil tank and turbocharger, On the right side of engine includes fuel filter, intake manifold, common rail, fuel pump, starter motor and oil tank can be investigated to see effect on engine noise. The noise examined reveals which direction of engine is dominant and which component in this direction is dominant over which engine operating conditions. While each component is in its position on the engine, a modal analysis test is performed to find outt which frequencies the components are more sensistives to, in other words natural frequencies.
In order to reduce motor noises in internal combustion engines, knowing which side of the engine is tiresome, and which engine components are dominant, will provide a roadmap for where to start in engine noise reduction work. In addition, these motors can be used as reference motor data and these data can be used comparatively to find the root cause of problems in other motors produced in serial production. Thus, the source of motor noise can be detected quickly. In addition, whether the acoustic camera used for source detection correlates to the motor noise sources detected by the accelerometer and microphone data is examined at different speeds of the motor and at different frequency ranges.
The dominant noise generating center frequencies on the left and right of the engine have been determined. These center frequencies were cut in 20% band width and acceleration values of the engine components were examined from 800 rpm to 2100 rpm in full load conditions of engine. From these acceleration values, the dominant noise source of the engine was determined by determining which component dominated which engine speed. The detected noise were examined at which frequencies the acoustic camera was more effective in detecting engine noise source.
The results of the thesis;
•	The noise values of the motor under full load conditions and the acceleration values of the motor components are higher than the noise and acceleration values at the engine zero load conditions and the idling speed.
•	When we examine the noise data of the engine, the right side of the engine has highest noise at engine all revs under full load conditions. On the assumption that the load is zero, the noise levels emitted from the right and left surfaces of the engine is similar up to 1750 rpm. After 1750 rpm, the noise level on the right side of the engine is at higher levels.
•	When the noise levels at the enigne idle speed are examined, the noise level at the left side of the motor is highest. The lowest noise level occurs on the side surface of the engine. Because engine surface area is the lowest at this side.
•	Inspected components on the left side of the engine are oil filter, water pump, oil tank, turbo; The components examined on the right side of the engine are alternator, fuel filter, intake manifold, fuel line, fuel pump, starter motor and oil tank.
•	The noisy dominant center frequencies on the left side of the engine stand at 400 Hz, 680 Hz, 900 Hz, 1333 Hz, 1460 Hz, 1693 Hz and 1970 Hz.
•	The noise source around 400 Hz (360 Hz - 440 Hz) on the left side of the engine is the oil tank because the acceleration value of the oil tank is higher at all engine revolution. Water pump has the lowest level of noise source as it has the lowest acceleration value at all engine revolutions. In the modal analysis test, the oil tank has a mode around 395 Hz.
•	The noise source around 680 Hz (612 Hz - 748 Hz) on the left side of the engine is oil filter because the acceleration value of the oil filter is higher at all engine revolution. Also in the modal analysis test, the oil filter has a mode around 600 Hz. The close proximity of this point to the investigated frequency domain is the main reason why the oil filter is the dominant noise source.
•	Oil tank and oil filter stand out as a noisy source of over 900 Hz (810 Hz - 990 Hz) on the left side of the engine. The acceleration values of the oil tank and the oil filter at all engine revolutions are higher than the acceleration values of the turbo and water pump.
•	The oil filter stands out at all engine revolutions as a noisier dominant source at 1333 Hz (1200 Hz - 1466 Hz) on the left side of the engine. The water pump is considered the lowest noise source.
•	On the left side of the engine, the oil filter stands out as a noisy source around 1460 Hz (1314 Hz - 1606 Hz). When we sort the noise sources in this frequency range, the order from highest noise to lowest noise source is as follows: oil filter, oil tank, turbo and water pump.
•	The noise dominant center frequencies on the right hand side of the engine stand at 250 Hz, 409 Hz, 647 Hz, 720 Hz, 820 Hz, 890 Hz, 1100 Hz, 1630 Hz and 1770 Hz.
•	Noise at 250 Hz (225 Hz - 275 Hz) on the right side of the engine, alternator is main contirutor of  engine noisy between 1100 rpm and 1600 rpm due to vector sum of the acceleration values in the three directions of the alternator is highest. Also, in the modal analysis test,  the alternator showed resonance at around 239 Hz.
•	Noisy around 720 Hz (648 Hz-792 Hz) on the right side of the engine, It has been observed that the fuel filter is the main noise source between 1200 rpm and 1450 rpm. At 1600 rpm to 1900 rpm, noise from the alternator becomes dominant. The lowest noise sources are the oil tank and the starter. In the modal analysis test, the alternator showed resonance at around 753 Hz.
•	Noisy at 890 Hz (801 Hz - 979 Hz) on the right side of the engine at all engine revolutions, fuel line is main engine noise source. In the modal analysis test, it is seen that the fuel line enters the resonance with 834 Hz. It is seen that the oil tank and the starter motor are the lowest noise source.
•	Noisy around 1770 Hz (1593 Hz - 1947 Hz) on the right side of the engine at all engine revolutions, fuel filter is main engine noise source. Due to the fact that the acceleration values of the vector sum of the vibrations of the fuel filter in the x, y and z directions are higher.
•	Engine components noise level have been examined by using acoustic camera. Due to the environmental obstacles in the acoustic room , only the right and left engine noise data are taken by using acoustic camera. In addition, when we examine the engine noise data, it is seen that the noise is the most dominant noise source on the left and right sides of the engine.
•	When noise data of engine components are analyzed by using acoustic camera, especially after 1000 Hz, the acoustic camera is more effective detecting the source of engine noise but It was seen that it was not effective to detect the engine noise source at frequencies lower than 1000 Hz.