Turbocharger

A turbocharger, comprising:

• a shaft;
• a turbine configured to expand a first medium comprising:
• a turbine housing;
• a turbine rotor;
• turbine rotor blades of the turbine rotor;
• and
• a turbine-side gap defined between radially outer edges of the turbine rotor blades and a portion of the turbine housing facing the turbine rotor blades or a stator-side component connected to the turbine housing;
• a compressor configured to compress a second medium utilizing energy extracted in the turbine during expansion of the first medium, the compressor comprising:
• a compressor housing;
• a compressor rotor:
• compressor rotor blades of the a compressor rotor coupled to the turbine rotor via the shaft;
• and
• a compressor-side gap defined between radially outer edges of the compressor rotor blades and a portion of the compressor housing facing the compressor rotor blades or a stator-side component connected to the compressor housing;
• a bearing housing arranged between and connected to the turbine housing and the compressor housing and in which the shaft is mounted;
• and
• a running-in structure comprising hollow spaces is at least one of:
• the portion of the turbine housing facing the turbine rotor blades or the stator-side component connected to the turbine housing and
• the portion of the compressor housing facing the compressor rotor blades or of the stator-side component connected to the compressor housing.