What causes turbo compressor surge?
This could be caused by a dirty charge air cooler, or dirt or contamination on a nozzle ring, for example. A malfunction of valve timing or of the engine fuel system are other potential issues that can result in surging, occasionally caused by irregular and unsteady fuel injection. Since the turbo is actually making significant boost, is at high RPM, and the pressure is fluctuating wildly because of the surge, these conditions do have the potential to cause greatly accelerated turbo bearing wear and/or damage to the compressor wheel.If you notice that your boost pressure is higher than normal this can be a really bad situation. Too much pressure can cause significant damage to the turbocharger or engine. If you are pumping in too much fuel and air into an engine it can exceed what the engine is built to withstand and cause a blown head gasket.Turbo flutter happens when the turbo reaches a surge condition. The surge condition happens when the difference in pressure in the intake versus the speed of the air passing through the turbo becomes too large.Turbocharger surging occurs when the pressure of the exhaust gas is higher than the scavenge air pressure and hence backpressure develops in the turbocharger. Usually noise and/or vibration is observer on the Turbocharger when surging occurs, while turbocharger RPM fluctuates rapidly.Fluctuations in pressure cause the turbocharger to surge when airflow becomes inconsistent. A mismatch between the engine’s air demand and the turbocharger’s air supply often causes surging. These fluctuations make the turbo accelerate and decelerate repeatedly.
What causes a compressor surge?
Surge in a centrifugal compressor is an unstable condition where the compressor cannot maintain the required discharge pressure due to low flow rates. This instability causes rapid fluctuations in flow rate, pressure, as well as temperature, often with severe vibrations and noise. During the surge, a significant mass gas will flow in the reverse direction. As a result of a large dynamic force act on the impeller or blading within the compressor. Due to this the components of the compressor (such as thrust bearings, bearing, casing) exposed to large changes in axial force on the rotor.Compressor surge is a form of aerodynamic instability in axial compressors or centrifugal compressors. The term describes violent air flow oscillating in the axial direction of a compressor, which indicates the axial component of fluid velocity varies periodically and may even become negative.Surge can be avoided by ensuring the flow through the compressor is not reduced below the flow at peak head. The surge avoidance system prevents surge by modulating a surge control (bypass) valve around the compressor.Surge occurs when there is no forward flow of gas through the compressor and a reversal of flow occurs. The gas that is being compressed gets pushed backward through the centrifugal compressor. When this surge (flow reversal) occurs, which can happen in milliseconds, the rotor is affected.Surge happens when flow drops below a critical point, leading to a cyclic pattern of flow reversal and re-establishment.
How to fix compressor surge?
To stop if from happening we move our turbo away from the surge line (move to the right side of the line) on the compressor map. We can’t magically make the engine move more air at the same boost pressure and RPM but we can gradually reduce boost at the RPM where the surge occurs until the problem stops. Since the turbo is actually making significant boost, is at high RPM, and the pressure is fluctuating wildly because of the surge, these conditions do have the potential to cause greatly accelerated turbo bearing wear and/or damage to the compressor wheel.Thus, turbo flutter, also referred to as the compressor surge, is the sound when you step off the accelerator after reaching peak boost.Turbo surge is when there’s too much back pressure in the system, usually due to bad waste gates and/or blowoff valves. That causes sudden changes in the air pressure in the turbo, which causes vibrations, loss of boost, etc. Definitely a bad thing.To stop if from happening we move our turbo away from the surge line (move to the right side of the line) on the compressor map. We can’t magically make the engine move more air at the same boost pressure and RPM but we can gradually reduce boost at the RPM where the surge occurs until the problem stops.
How to stop open throttle compressor surge?
So what should I do if I have open throttle surge? Based on what we learned from the compressor map, if you have open-throttle surge under particular driving conditions, your only options are to reduce boost or increase airflow under these conditions, or drive around the problem! To stop if from happening we move our turbo away from the surge line (move to the right side of the line) on the compressor map. We can’t magically make the engine move more air at the same boost pressure and RPM but we can gradually reduce boost at the RPM where the surge occurs until the problem stops.
How to avoid surging in a compressor?
Surge can be avoided by ensuring the flow through the compressor is not reduced below the flow at peak head. The surge avoidance system prevents surge by modulating a surge control (bypass) valve around the compressor. To prevent surge from occurring, a minimum flow controller must be implemented. As the pressure ratio increases, the surge limit flow increases. For many compressor applications, operating at lower flows also requires less pressure.Surge occurs when there is no forward flow of gas through the compressor and a reversal of flow occurs. The gas that is being compressed gets pushed backward through the centrifugal compressor. When this surge (flow reversal) occurs, which can happen in milliseconds, the rotor is affected.Conclusion. With an understanding of the mechanics of compressor surge and the conditions that cause it, it can be seen that in the majority of cases it will not cause significant turbo wear or damage, however there is the potential if it is severe enough.A good rule of thumb for adequate surge limit line is about 5% in compressor head or 10% flow, whichever provides greater margin, from the surge line. A surge event can cause irreparable damage to compressors and leave processes that require these machines down for weeks; don’t let surge happen to you!
What causes surges in compressors?
Surge occurs when there is no forward flow of gas through the compressor and a reversal of flow occurs. The gas that is being compressed gets pushed backward through the centrifugal compressor. When this surge (flow reversal) occurs, which can happen in milliseconds, the rotor is affected. Surge Line Surge is the left hand boundary of the compressor map. Operation to the left of this line represents a region of flow instability.An anti-surge valve is specifically designed and installed to protect the compressor from reaching its surge point.Surge testing ensures the anti-surge control system accurately detects and prevents surge. Testing typically happens in the field after the compressor has been in operation for some time.