<?php 
$term = get_queried_object(); // Get the current taxonomy term

// load thumbnail for this taxonomy term
$img = '';
$img = get_field('image', $term->taxonomy . '_' . $term->term_id);
if($img){
?>
 <img src="<?php echo $img['url']; ?>" alt="<?php echo $img['alt']; ?>" />
<?php
}
?>