What is N1 and N2 in aircraft engine?
N1 and N2 are terms used to describe the rotation speeds of the two primary spools in a multi-spool jet aircraft engine. These parameters are important for engine monitoring and control, and they are typically displayed in the cockpit to provide crucial information to the flight crew. N1 and N2 express the rotational speed of turbine engines as a percentage of the maximum normal operating RPM. N1 is the speed of the low pressure spool and serves as the primary power setting, and N2 is the speed of the high pressure spool which indicates if aircraft systems have sufficient power.The N1 Indicator is a cockpit gauge which presents the rotational speed of the low pressure (low speed) engine spool, a speed that is referred to as N1. The gauge is usually calibrated in percent RPM based on an engine manufacturer defined rotational speed that corresponds to 100%.On many jet engines, N1 is the primary indication of engine thrust and determination of a target N1 is an important facet of the takeoff performance calculations. Engine Pressure Ratio (EPR) is used for the same purpose on other engine types.
What is N1 and N2 in an engine?
N1 and N2 express the rotational speed of turbine engines as a percentage of the maximum normal operating RPM. N1 is the speed of the low pressure spool and serves as the primary power setting, and N2 is the speed of the high pressure spool which indicates if aircraft systems have sufficient power. In an axial flow jet engine, N1 refers to the rotational speed of the low speed spool which consists of the fan, the low pressure compressor and the low pressure turbine, all of which are connected by a concentric shaft.N1 and N2 are the speeds of a turbofan engine, respectively the LP compressor and turbine, and the HP compressor and turbine. Most turbofans and turbojets have w spools (a matched pair of compressor and turbine), but for those with 3 spools, as commonly used by Rolls Royce, there will also be an N3.In a two spool axial flow jet engine, N2 refers to the rotational speed of the high speed spool which consists of the high pressure compressor and the high pressure turbine.The N2 shaft of a turbofan engine connects the high-pressure compressor and high- pressure turbine in the core.